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01-25-07 Town Council PacketSNOWMASS VILLAGE TOWN COUNCIL SPECIAL MEETING AGENDA JOINT MEETING WITH UU SNOWMASS WATER AND SANITATION DISTRICT JANUARY 25, 2007 CALL TO ORDER AT 9:00 A.M. Item No. 1: ROLL CALL Snowmass Village Town Council Snowmass Village Water and Sanitation Item No. 2: PUBLIC NON-AGENDA ITEMS 5-Minute Time Limit) Item No. 3: DISCUSSIUON ITEMS Review of W.W. Wheeler Dry Analysis and Evaluation of Raw Water Storage Item No. 4: CONSTRUCTION MANAGEMENT Item No. 5: ADJOUNRMENT NOTE: ALL ITEMS AND TIMES ARE TENTATIVE AND SUBJECT TO CHANGE WITHOUT FURTHER NOTICE. PLEASE CALL THE OFFICE OF THE TOWN CLERK AT 923-3777 ON THE DAY OF THE MEETING FOR ANY AGENDA CHANGES. PLEASE JOIN TOWN COUNCIL FOR A SOCIAL AT WILDCAT CAFE AFTER TONIGHT'S MEETING. S N O W M A S S NOTICE OF SPECIAL MEETING WATER 8L SANITATION N l r I. STATE OF COLORADO COUNTY OF PITKIN ss. SNOWMASS WATER AND ) SANITATION DISTRICT PUBLIC NOTICE IS HEREBY GIVEN that a Special Meeting of the Board of Directors of the Snowmass Water & Sanitation District will be held at the Town of Snowmass Village Council Chambers at 16 Keams Road, Snowmass Village, Pitkin County, Colorado on Thursday, January 25, 2007 at 9:00 a.m. for the consideration of business pending before said Board of Directors. Any taxpaying electors of the District or interested persons may attend the meeting, which will be open to the public. DATED THIS 22nd DAY OF JANUARY 2007 SNOWMASS WATER AND SANITATION DISTRICT SNOWN A.SS WklER & SAM'I%]IoN DiS"INI( I • Rosi Of icF f3 x 5700 • 017711.irommr DHIVr. - SNUWVAS$ Vu i AI& ('ni,)k.Ann ,11615 D:i rrm,m )70.023 2056 • Fns .umi.r 970.'C1.6271 • "%kv.vasd.oru R Z2 SNOWMASS SPECIAL MEETING— 25 JANUARY 2007 at 9:00 a.m. WATER & SANITATION I S T R 1 c I' AGENDA 1.Call to Order 2.Roll Call 3.Review of W.W. Wheeler Dry Year Analysis and Evaluation of Raw Water Storage Requirements 4. Construc ion Management 5. Adjournment SNOWMASS WATER & SANII%TION DISTRICT • MIST OI FICI Box 5700 • 0177 CLI RHtG,SI- Dmvr . SMIWMASS UILI Atif • COLI IRAIR 0 A 1615 J I IJ•utINI 970.923_205() • P,,csrknu 90.923.6271 • wHw.swst1.oI, SNOWMASS WATER AND SANITATION DISTRICT DRY YEAR YIELD ANALYSIS FOR SNOWMASS CREEK WATER SUPPLIES AND EVALUATION Of RAW WATER STORAGE REQUIREMENTS Im SNOWMASS WATER AND SANITATION DISTRICT arm DAY YEAR YIELD ANALYSIS FOR SNOWMASS CREEK WATER SUPPLIES AND EVALUATION OF RAW WATER STORAGE REQUIREMENTS AMW Prepared for: Snowmass Water and Sanitation District Snowmass Village, Colorado AIM mmu- W. W. Wheeler and Associates, Inc. Water Resources Engineers 3700 So. Inca Street Englewood, Colorado 80110 October 20, 2006 a:\1200\1257\1257.00.01\06102OR_SWSO_Study\061020R_SWSD Study.doc rR DRY YEAR YIELD ANALYSIS FOR SNOWMASS CREEK WATER SUPPLIES AND EVALUATION OF RAW WATER STORAGE REQUIREMENTS TABLE OF CONTENTS Page TABLE OF CONTENTS ........................................................................................ i LISTOF FIGURES................................................................................................ii LIST OF TABLES..................................................................................................ii EXECUTIVE SUMMARY FROM THE BOARD OF DIRECTORS.........................iii INTRODUCTION.................................................................................................. 1 MODEL DESCRIPTION .......................................................................................4 GENERAL ASSUMPTIONS AND OPERATIONAL COMPONENTS....................5 SUPPLY SIDE MODULE ............................................................................................ 5 DEMAND SIDE MODULE........................................................................................... 7 RESERVOIR OPERATIONS......................................................................................13 MODEL OPERATIONAL SCENARIOS.............................................................. 14 SUPPLY SIDE SCENARIOS......................................................................................14 DEMAND SIDE SCENARIOS....................................................................................15 DEMAND SCENARIOS EXAMINED..........................................................................16 MODELING APPROACH AND RESULTS ......................................................... 18 DEFINITIONS FOR MODELING RESULTS...............................................................18 HIGHLIGHTS OF RESULTS......................................................................................19 ADDITIONAL CONSIDERATIONS.................................................:...................27 DOWNSTREAM AND COLORADO RIVER MAIN STEM WATER CALLS.................27 DISTRICT'S RESERVOIR WATER STORAGE RIGHTS...........................................27 WATER SUPPLY FOR AN EXTENSION OF THE SNOWMAKING SEASON............27 LIST OF FIGURES Page Figure 1 - General Location Map ................................................................................... 3 Figure 2 - Storage Utilization for 1977 ......................................................................... 23 Figure 3 - Storage Utilization for 2002 - 2003 .............................................................. 24 LIST OF TABLES Page Table 1 - Current Demand per EQR .............................................................................. 8 Table 2 - Snowmass Creek Flow Limitations per Agreements ..................................... 11 Table 3 - Determination of Required Raw Water Storage for 1977 Study Period.......... 20 Table 4 - Determination of Required Raw Water Storage for 2002-2003 Study Period. 21 SNOWMASS WATER & SANITATION D 1 S T R 1 C T EXECUTIVE SUMMARY FROM THE BOARD OF DIRECTORS To assist in the review and understanding of W. W. Wheeler and Associates Report, the Board of Directors of the Snowmass Water and Sanitation District has prepared this Executive Summary. Background. The Town of Snowmass Village by Ordinance No. 10, Series of 1987 established zoning for undeveloped property with the Town. Subsequently, the District reevaluated its potable water and sanitary sewer systems to insure that adequate capacity existed to serve potential development. During the 1990's, the District water treatment and sewage treatment plants were both upgraded to provide additional capacity and system reliability. Development approvals by the Town during the 1990's were consistent with the zoning parameters established in Ordinance No. 10 and with the District's equivalent residential unit water usage future demand estimates. More recently, the Town has granted development approval for Base Village and is considering proposed Snowmass Center and Mall redevelopment. The Base Village approval and the proposed redevelopment anticipated water demand exceeds the District's demand estimates that were based upon prior approved zoning for these projects. To understand the potential impact of the recently approved and contemplated redevelopment on District planning for future water demand, the Board of Directors of the District determined that a thorough review of the yield available under District water rights was necessary, in both normal and low flow water years. To supplement initial studies that were prepared in conjunction with the District's service plan, the Board further determined to seek an evaluation of the possible need for, and benefit of, securing raw water storage as a component of meeting future water demands and minimizing diversions from Snowmass Creek during periods of low stream flow. The Board sought the assistance of its water resources engineers, W. W. Wheeler and Associates, to provide the review and evaluation by preparation of the Report. Analysis and Implementation. The Report provides information that is intended to be used as a tool for operational, water resource and capital improvement planning by the District Board. The Board is now in the process of analyzing the Wheeler Report to determine if policies will be established to alter District operations or create new infrastructure. As the Report is not intended to be conclusive but to provide information that will allow for the Board to make informed determinations, no specific recommendation is made by Wheeler. Further study may be required to allow the Board to establish planning parameters from the information provided in the Report. Upon conclusion of the analysis by the Board, it is anticipated that an update to the District 1992 Facilities Report will occur by the issuance of a current Facilities Report. Additionally, the District will outline possible policies and procedures required to implement the conclusions of the Board. iii Report Executive Summary. For ease of the reader the major components of the Wheeler Report are summarized as follows: Demand. The projected District municipal demand is estimated for 3 levels of development, including future water demand resulting from the Existing Municipal Demand including Base Village and Redevelopment projects, demand under the Town Comprehensive Plan Build-Out Chart, and a maximum development demand level that may result from additional redevelopment and infill development within the District. Consistent with historical practice, the supply of water to meet snowmaking demands, contractual service obligations, and other operational requirements is also considered. The study assumes a voluntary Stream Flow Stewardship Goal of 7 cubic feet per second (cfs) bypassing the District's Snowmass Creek Pump Station diversion, provided alternate sources of water are available to meet District demands in lieu of further diversions from Snowmass Creek during periods of low flow. While the District is legally entitled to divert at times its water rights are in priority, when the flow in Snowmass Creek is below 7 cfs by contractual agreement certain diversion events below established trigger point flow rates necessitate implementation of mandatory conservation measures and increased billing rates to District customers. The analysis also assumes that the District may desire to maintain a raw water storage capacity reserve of potable water usage in the event of catastrophic failure of the primary delivery systems. A catastrophic event could result from uncontrollable loss of supply due to a landslide, blockage or other ,interruption of the District's primary delivery systems, or from contamination or unacceptable turbidity rendering the raw water sources of supply untreatable. The discussion of catastrophic storage in the Report was requested by the Board to provide information on a perceived worst case scenario and to allow for a review of system reliability at times of low flow and high demand. Yield. This report analyzes the legal and physical availability of water under the District's water rights in view of a maximum historical diversion scenario for water rights on Snowmass Creek during two historical dry periods represented by the 1977 and 2002-2003 drought years. Analysis. The analysis indicates that during two historical dry periods represented by the 1977 and 2002-2003 drought years, the District may not be able to meet all future development demands on a number of days without the implementation of additional mandatory water conservation measures, the creation of raw water storage or a combination of both additional conservation and storage. The Report evaluates the amount of raw water storage.that would be required to meet anticipated demand without additional mandatory water conservation measures, maintain the 7 cfs Stewardship Goal to the extent possible, and provide storage reserves for a catastrophic event. Neither treated water storage, nor potential additional raw water storage, would be utilized directly to supplement low stream flows to meet the Stewardship Goal, as this could deplete required fire and short-term emergency supplies should a delivery system catastrophe occur. In 1977, the volume of storage required to iv meet District demand and the Stream Flow Stewardship Goal, as well as maintain catastrophic event storage, ranges from 255 acre-feet to 330 acre-feet for the respective development scenarios. In 2002, the storage requirements range from 175 acre-feet to 200 acre-feet. The amount of catastrophic event storage to meet District demand for 3 weeks ranges from 105 acre-feet to 120 acre-feet, assuming East Snowmass Creek and Snowmass Creek delivery systems are rendered unusable. The Report does not identify or examine any particular raw water storage site and, as such, the raw water storage capacities discussed could be developed in single or multiple storage sites. Questions or comments regarding the Wheeler Report should be addressed to the Board through Kit Hamby, District Manager. SNOWMASS WATER & SANITATION DISTRICT Dave Spence, President and Director Richard Stumpf, Vice-President and Director Doug Throm, Secretary/Treasurer and Director Rhonda J. Bazil, Director Jack Hatfield, Director v DRY YEAR YIELD ANALYSIS FOR SNOWMASS CREEK WATER SUPPLIES AND EVALUATION OF RAW WATER STORAGE REQUIREMENTS INTRODUCTION At the request of Snowmass Water and Sanitation District (District), W. W. Wheeler and Associates (Wheeler) has prepared this study to examine dry year water supply demand and yield of District water supplies. The District is situated in the Brush Creek drainage, and has water rights and diversion facilities located in both the Brush Creek drainage and the Snowmass Creek drainage. Refer to Figure 1 for the general location of the District and its major facilities. District water supplies are derived primarily from East Snowmass Creek due to impaired.water quality and limited physical supplies in the Brush Creek drainage. A primary component of this study is the evaluation of the possible need for, and benefit of, raw water storage in meeting District water demands, minimizing diversions from Snowmass Creek during periods of low stream flow and maintaining municipal water service during a catastrophic event that renders District water supplies either undeliverable or untreatable. The objective of the study is to examine the probable yield of the District's water rights during two historical dry periods represented by the years 1977 and 2002 - 2003. The study will assess how additional raw water storage capacity will assist the District in meeting its future raw and treated water demands with anticipated growth of the District, and simultaneously meet a Stream Flow Stewardship Goal on Snowmass Creek. The approach to be used to assess the impact and benefit of raw water storage is to examine the impact of increased District demand and the Stream Flow Stewardship Goal on the volume of raw water storage required. The District has elected to implement a Stream Flow Stewardship Goal program on Snowmass Creek that will operate to minimize diversions from Snowmass Creek and Page 1 tributaries during periods of low stream flow. This program is discussed in more detail later in the report. This study does not identify or examine any particular raw water storage site and as such the raw water storage capacities identified through this analysis can be developed at one site, or can be an accumulation of capacity developed at a number of smaller storage sites. Page 2 1 1 f I I r DISTRICT BOUNDARY WASTEWATER TRFTMENT% ANT •. 1 SNOMASSCREEK A$ NOWMASS' PUMSTAnON CREEKPLE Nr n ^ TOWN OF VILLAGE 7= - NOWMASS l WATER TREATMENT WESTFORKSRUSH ---CREEK PIPFUNE I. z F EAST SNOWMASS i CREEK AND BRUSH.. EAST FORK BILISH CREEK% PELINF, REEK PIPELINE Snmw s Water E o a SW XWw DSllml C S, G SNOWMA$$ o Ganertd tncalion Map SKIAREA " I 0 Yi Ya US m maws. Scale in MYq .. 1257E Figure 1 e MODEL DESCRIPTION A computer-based water supply and system analysis model of the District was prepared to evaluate the study's objectives. The model consists of two separate modules. The first module is a Supply Side model which models water that is physically and legally available. This model is focused primarily on East Snowmass Creek and Snowmass Creek, which is the primary dry-year supply for the District simply because the available water supplies in the Brush Creek drainage are minimal in the dry years. The second module is a Demand Side model that determines the Snowmass Creek diversions based on the District demands and the District's Stream Flow Stewardship Goal for supporting a minimum flow level in Snowmass Creek. The Demand Side module uses the results from the Supply Side model as the water availability and stream impact boundary, and evaluates raw water storage requirements to meet these demands and goals. The Supply Side model explicitly operates the East Snowmass Creek and the main stem Snowmass Creek decreed water rights in a water balance format, assuming strict priority of diversions for water rights, and determining the legal and physical availability of water under the District's water rights. The Supply Side model, as well the Demand Side model, use the 1977 and 2002 - 2003 droughts as representative extremely dry periods for analysis. The Supply Side model is operated on a daily basis for the periods of interest, extending from June 1976 through July 1976 and January 2002 through September 2004. The droughts of 1977 and 2002 are the first and second driest periods in the past 100 years, respectively, in terms of monthly flow of the Roaring Fork River at Glenwood Springs stream gaging station. Page 4 GENERAL ASSUMPTIONS AND OPERATIONAL COMPONENTS The following general assumptions and operational components apply to all of the modeled scenarios. The general assumptions and operational components are described below for each model module they are input into. SUPPLY SIDE MODULE The Supply Side Module has two major components: 1) stream flow records Snowmass Creek and tributary inflow), and 2) water rights diversion information (stream diversion and in-stream flow rights). Snowmass Creek Virgin Flow Mydrograph. The Snowmass Creek virgin flow hydrographs used in the Supply Side Module for the 1977 and 2002 - 2003 periods were estimated using two distinctly different methodologies. The 1977 flows were synthesized as a percentage of near by Maroon Creek flow records for the 1977 period, and the 2002 - 2003 flow records were based on actual flow records and correlations for missing data. Baseline virgin flows were determined for Snowmass Creek at the District's Snowmass Creek Pump station. The 1977 synthetic flows on.Snowmass Creek were based on the flow in Maroon Creek correlated to Snowmass Creek using a ratio of synthetic flows for both Snowmass and Maroon Creeks. The ratio was based on estimated monthly flows on both Snowmass and Maroon Creeks, found using the methodology presented in Water Resources Investigation Report 85-4086. The District provided stream flow records measured at the Snowmass Creek pumping station for the 2002 to 2003 study period. The records provided contained gaps" and also periods known to be inaccurate. To fill in the gaps and adjust the records for periods known to be inaccurate, monthly factors were determined to correlate flows recorded on the Roaring Fork above Aspen (corrected for major diversions) and those measured as bypassing the District's Snowmass Creek Pump Station. The monthly correlation factors were based on periods believed to have accurate records at Page 5 both locations. The monthly correlation factors in conjunction with the Roaring Fork above Aspen flow records were used to estimate flows at the Snowmass Creek Pump Station. Upstream diversions for the period of interest were added to the Snowmass Creek Pump Station to obtain an estimate of the virgin flow for Snowmass Creek. The synthetic (correlated) period of streamflow record was April 2002 through October 2002. Downstream Tributary Inflow. Tributary inflow to Snowmass Creek, downstream from the District's Snowmass Creek Pump Station, was accounted for in the model at three major tributaries: Hunter Creek, Wildcat Creek and Capital Creek. Tributary inflow values were estimated based on a percentage of Snowmass Creek virgin stream flows. The inflow from Hunter Creek and Wildcat Creek is based on a correlation of tributary area and mean basin elevation verses monthly stream flow at gages in the Roaring Fork basin. Inflow from Capital Creek was assumed equal to the calculated streamflow in Snowmass Creek at the junction of the two streams, which is believed adequate for modeling the short, lower reach of Snowmass Creek below Capital Creek and above the Roaring Fork River. Water Rights. The District's and other Snowmass Creek water rights that divert from East Snowmass Creek and Snowmass Creek were explicitly modeled. Only non- District water rights with an absolute decreed rate of 1.0 cis or more were considered in the model, i.e., smaller stock water use and domestic water rights were not modeled. The District's Brush Creek water rights (rights that divert from Brush Creek, West Fork Brush Creek and East Fork Brush Creek) were considered in a more general way under the assumption that in a dry year very little water would be available under those rights. The impact of the Brush Creek rights is accounted for in the Demand Side model. In-Stream Flow Rights. The minimum in-stream flow right for Snowmass Creek, between the confluence with West Snowmass Creek and the confluence with Capital Creek, for the critical October 166' through March 31" period, is a variable rate dependent upon the stream flow recurrence interval during an indicator stream flow period of October 11"' through October 15'". During 1977 the average daily stream flow during the indicator period was less than 19-cfs, and therefore, in accordance with the in- Page 6 stream flow right, the predicted stream flow recurrence interval is 1 in 10. The resulting in-stream flow right would be 9-cfs from October 16d' through October 21°1, 8-cfs from October 22nd through October 31 st, 7-cfs from November I"through December 31°', and 8-cfs from January 181 through March 31". During 2002 the average daily stream flow during the indicator period was greater than 29-cfs and therefore in accordance with the in-stream flow right, the predicted stream flow recurrence interval is 1 in 2. The resulting in-stream flow right would be 12-cfs from October 16d' through December 31", and 10-cfs from January 1° through March 3181. It is noted that subsequent stream flow in the study periods represented a significantly more severe drought period than the indicator suggested. DEMAND SIDE MODULE The Demand Side Module is used to model the Districts water use components which include municipal uses within the District, Snowmaking (at the Snowmass Ski Area), contractual deliveries to Brush Creek Metropolitan District and Wildcat Ranch, and incidental uses including treatment plant backwashing. Additional Demand Side Module components include pipeline and pump station capacities, stream diversion limitations, and stream flow stewardship goals. Lastly, the Demand Side Module includes a component for Brush Creek water supplies. Detailed descriptions for the above Demand Side components are provided in the following sections and paragraphs. Municipal Uses Within the District. Municipal demands within the District were examined for three levels of development. For each level of development municipal demand is based upon the total of the existing and a projection of future Equivalent Residential Units (EQRs). EQRs and the levels of development are discussed in the following paragraphs. Average Use per EQR. The current average daily municipal water use per EQR presented in the Table 1 below were derived from 2005 monthly plant production records, reduced by the amount of treated water provided to Brush Creek Metro, and Page 7 adjusted to quarterly EQR data provided by the District. Future municipal water use in the District is assumed to follow a similar seasonal pattern and usage. TABLE 1 CURRENT DEMAND PER FOR Quarterly Average Daily Month EQRs Use per EQR al January 266 February 4,483 269 March 263 April 182 May 4,547 300 June 489 July 525 August 4,562 523 September 415 October 192 November 4,563 172 December 258 Annual Average 4,539 323 For the purpose of analyzing the amount of raw water storage needed to maintain municipal water service during a catastrophic event, a range of municipal demands from 172 to 275 gallons per day per EQR was considered. The maximum average municipal daily use of 275 gallons per day per EQR was used for examination of a catastrophic event that occurs during the summer months since all outside irrigation would be curtailed. Levels of Develooment. The projected municipal demand was examined for three Levels of Development as defined below. 1. Existing Municipal Demand With Base Village and Redevelopment. The projected Level of Development for Existing Municipal Demand With Base Village and Redevelopment is estimated to be 5,900 EQRs. This Level of Development includes the existing municipal demand (4,600 EQRs), and the projected increases in District water demand resulting from the Base Village Page 8 800 EQR) and Re-Development projects (500 EQR). According to the District, projects included in the 500 EQR Redevelopment are Snowmass Center Re-Development, Mall Revitalization, Employee Housing Projects, Entryway Project and Town Hall Project. 2. District Build-Out. The projected Level of Development at District Build-Out is estimated to be 6,200 EQRs. The additional 300 EQRs that are included in this Level of Development, in addition to the Existing Municipal Demand With Base Village and Redevelopment Level of Development, are an estimate based on the Town of Snowmass Village Comprehensive Plan Build-Out Chart. 3. Build-Out With Reserve. The projected Level of Development at Build-Out With Reserve is estimated to be 6,800 EQRs. This Level of Development is an assumed maximum development level that may result from additional future redevelopment and infill development within the District. This level of development is 110 percent of the District Build-Out development level. The total number of EQRs in the District at each level of development was used in conjunction with the most recent historic water usage records to estimate the District demand for each Level of Development. Snowmaking. The snowmaking demand for Snowmass Ski Area currently totals about 50 MG beginning in the middle of October and extending through the end of December. Snowmaking uses are generally supplied as 2.25 MGD (7 ac-ft per day) for three consecutive days every ten days (i.e. three days of snowmaking and then seven . days with no snowmaking, for a total snowmaking volume of 6.75 MG (21 ac-ft) every 10 days). Snowmaking use is currently decreed for and provided by the junior East Snowmass Brush Creek Pipeline and Snowmass Creek Pipeline water rights Administration Number 52013), which are junior to the Snowmass Creek minimum stream flow water right. These water rights are decreed for snowmaking use during the October 15 through December 31 each year. The snowmaking water rights, the junior East Snowmass Brush Creek Pipeline and Snowmass Creek Pipeline, are not decreed for storage. It is assumed that only short term operational storage will be utilized for operating these snowmaking water rights, and therefore the potential snowmaking water Page 9 right storage volume is assumed equal to seven days of the average daily snowmaking delivery, 0.68 MGD, for a total raw water operational storage requirement of 15 ac-ft. The Demand Side Model utilizes the above assumptions for meeting snowmaking demands. Brush Creek Metro Demand. Treated water is supplied to the Brush Creek Metropolitan District by the District in accordance with agreement. The treated water supplied to the Brush Creek Metro was accounted for, in general accordance with the contractual agreement which calls for delivery of a maximum of 150,000 gallons per day not to exceed 2 million gallons per month, in the Demand Side module as the average daily demand by month. The average daily demand used in the model was determined as a function of the average monthly deliveries based on 2003 -2006 records provided by the District. Wildcat Ranch. During the irrigation season, the District has contracted to deliver irrigation water to Wildcat Ranch from Snowmass Creek at a rate of 3.0 cfs from the Christensen Ditch water right for as long as the Christensen Ditch is in priority, and up to a maximum of 150 acre feet of consumptive use. Based upon our discussions with the District, in practice the 2.0 cfs is provided any time the Christensen Ditch is in priority, and is modeled as such. Backwashing. The volume of water used to model backwashing of the treatment system is a monthly percentage of plant production. The monthly percentage is based on 2005 plant production and backwashing volumes provided by District personnel. The water required for backwashing the system ranges from 0.9 percent in September to 1.4 percent in April of the water treated for District use. Brush Creek Water Supplies. Based on information provided by the District, it is our understanding that due to the inferior water quality of Brush Creek, the District is only able to utilize water from Brush Creek if it is used in conjunction with water obtained from East Snowmass Creek or Snowmass Creek. Based on an examination of the District's water production records, Brush Creek sources are estimated to produce 10 Page 10 percent of the total water treatment plant production each day. This volume generally corresponds to the maximum expected yield of the Brush Creek sources in a dry year. Pipeline/Ditch Capacity. For the purpose of determining how much of the District's legally and physically available water the District facilities can actually convey, the East Snowmass and Brush Creek Ditch and Pipeline, and the Snowmass Creek Pipeline capacities were considered. The District's records indicate the total combined capacity for the Snowmass and East Snowmass and Brush Creek Pipelines is 11.1 cis. The combined pipeline capacity was used as the upper boundary for the amount of water the District can divert from East Snowmass and Snowmass Creeks. Stream Diversion Limitations. The "1978" and "Trigger Point" agreements regarding the District's operations require the District to implement conservation measures when the flow in Snowmass Creek drops below certain rates of flow as a result of the District's diversions. Table 2 below, provided by the District's attorney Steve Connor, Esq., summarizes the 1978 and Trigger Point agreements with regard to stream flow, diversion limitations and required conservation measures. TABLE 2 SNOWMASS CREEK FLOW LIMITATIONS PER AGREEMENTS Snowmass Creek Stream Flow Diversion Limitation and Contract/ Stream Flow Conservation Measure Agreement Stewardship Goals 12 cfs or greater No limitations No limitation, but must use all Brush12cfsCreeksourcestomaximum 1978 Agreement 9 cfs No limitation, but must commence Trigger Point public awareness program Agreement 7 cfs No limitation, but must institute Trigger Point mandatory conservation Agreement 4-6 cfs No limitation, but must institute Trigger Point increased billing rates Agreement 4 cfs Only for emergency situations 1978 Agreement Page 11 These limitations were used as the basis for the District's adoption of 7.0 cfs as the Stream Flow Stewardship Goal. It should be noted that under the Trigger Point Agreement, snowmaking diversions between October 15th and December 31st are exempted from the diversion limitations. An "event" (Snowmass Creek Flow drops below Stream Flow Stewardship Goals), which triggers the conservation measures, does not occur until diversions go below the trigger point flow rate on any: 1. 2 consecutive days for a duration of 6 hours or more each day; or 2. 3 cumulative non-consecutive days between April 1 st and March 31st the following year for a duration of 6 hours or more each day. The Trigger Point Agreement requires that the District impose mandatory water conservation on all users if a 7 cfs event occurs and impose a surcharge on all users who exceed their FOR gallon equivalent if a 6 cfs event occurs. Due to the development of this study's model to operate on an average daily basis, low flow events lasting less than one day were not necessarily reflected in the model results. It is assumed that these short-term events can be minimized through daily fluctuations in the treated municipal storage. Stream Flow Stewardship Goals. The District has elected to implement a Stream Flow Stewardship Goal program on Snowmass Creek that will operate to minimize diversions from Snowmass Creek and tributaries during periods of low stream flow. The Stream Flow Stewardship Goal has been established at 7.0 cis, which will be the minimum stream flow bypassing the District's Snowmass Creek Pump Station diversion below which the District will implement a reduction in the diversions from Snowmass Creek and tributaries. Diversion reductions would be limited to the availability of alternate sources of water to substitute for the diversion reductions. Storage releases will NOT be made to supplement low stream flows to meet the goal. The effective operation of this program will require alternate source(s) of water to meet Page 12 District demands, with the most likely. source being raw water storage in the form of reservoir storage. RESERVOIR OPERATIONS The District currently has treated water storage of 5.2 MG (approximately 16 ac- ft), estimated to provide about 3 days of District municipal water usage. For the study analyses, the District's future raw water storage capacity requirements are determined as additional volumes required above the existing capacity. Utilization of the District's treated storage in order to meet the Snowmass Creek Stream Flow Stewardship Goal is not recommended, as this could deplete required fire and short-term emergency supplies should a delivery system catastrophe and reduced treated storage volumes occur simultaneously. Raw water storage is operated on the assumption that if there is water in storage, and the Stream Flow Stewardship Goal is not being met, the raw storage water will be used in lieu of Snowmass Creek diversions, thereby supporting the stewardship goals for Snowmass Creek to the level being modeled (i.e., the Stream Flow Stewardship Goals). Support levels are limited to the amount of water diverted by the District from the Snowmass Creek basin, i.e., water from a raw water storage reservoir is used in the District's municipal system in lieu of Snowmass Creek diversions, but is not released to augment Snowmass Creek streamflow. Upon examination of initial model runs it was found appropriate to start the model assuming the raw water storage reservoir(s) are full on June 1st of 1977 for the 1977 analysis and on January 1`of 2002 for the 2002 - 2003 analysis. Page 13 MODEL OPERATIONAL SCENARIOS SUPPLY SIDE SCENARIOS The Supply Side Scenario (SS Scenario) model for Snowmass Creek operates the District's water rights as well as the downstream (non-District) water rights based on their relative priority and decreed amounts. The model determines the maximum flow legally and physically available from Snowmass Creek under the District's municipal water rights. The District's water rights that have not been transferred to or decreed for municipal uses were excluded from the model. Water calls from the main stem of the Roaring Fork River and the Colorado River are not modeled. The following three Supply Side Scenarios were initially used to account for non- District diversions on Snowmass Creek that can reduce the diversions of or call out the District's water rights in times of stream flow shortage: 1. Historic Dry Year Non-District Diversions; 2. Average Monthly Non-District Diversions; and 3. Maximum Monthly Non-District Diversions. At the District's direction, Wheeler has only included Maximum Non-District Diversions (Maximum Diversion) in the results and discussion sections of this memorandum. A detailed description of this scenario is provided in the following paragraph. Maximum Monthly Non-District Diversions. The Maximum Non-District Diversions is based on the monthly diversion records at each Snowmass Creek structure for the 1990 — 2004 period. The maximum historic diversions at each structure for each month (i.e. in June) were determined using data obtained from Colorado State Decision Support System's HydroBase database. These diversion rates are used as a maximum diversion limit for each diversion structure. The maximum historic diversions at each structure were distributed among the water rights that divert at said structure starting with the most senior and working toward the junior. The Maximum Diversion amounts Page 14 exceed the actual diversions that occurred during the dry years of the 2002 - 2003 study period, and reflect the recent maximum historical diversion that may occur in the future during such a future drought event under diligent operation of the downstream water rights. It is noted that these maximum historical values are frequently less than the maximum decreed rates of flow for the diversion structures. DEMAND SIDE SCENARIOS The Demand Side Scenarios (DS Scenario) are used to examine current and projected District demands as well as raw water storage requirements in relation to the available supply and meeting the Snowmass Creek Stream Flow Stewardship Goal by supporting, through reduction of diversions, a minimum level of flow in Snowmass Creek below the District's Snowmass Creek pump station. Additional assumptions and conditions are discussed below. Current Storage. The current treated water storage available to the District is about 16 acre feet (5.2 MG). Wheeler assumed that none of this storage would be utilized to assist in meeting Stream Flow Stewardship Goals or demand shortfalls other than short term peaking usage. Raw Water Storage Requirements. The raw water storage capacity required to meet District demand and the Stream Flow Stewardship Goal are determined for each operational scenario. It is noted that additional raw water storage would be required to provide for storage reduction due to evaporation and seepage losses, as well as a possible dead storage pool, that are expected to occur with a raw water reservoir. Storage Reserve for Catastrophic System Failure. The model analyses are developed on the assumption that the District's Snowmass Creek and East Snowmass Creek delivery systems are usable on a day-in day-out basis. It is conceivable that a catastrophic event, such as landslide, flood or forest fire could• significantly damage either or both delivery systems, or render the water being delivered untreatable. These systems could remain out of service for an indeterminate period of time, leaving the District with only its water storage facilities located within Brush Creek drainage. In Page 15 order to provide water service to the District for any extended delivery system down time, additional raw and/or treated water storage would be required in the Brush Creek basin. It would be prudent for the District to maintain a raw water reserve in event of a catastrophic failure of the primary delivery systems. A reserve storage capacity of up to 3 weeks of District potable water usage was examined, which is equal to 105 ac-ft for the current District commitments (Existing Municipal Demand With Base Village and Redevelopment). DEMAND SCENARIOS EXAMINED Three Demand Scenarios were assembled and utilized in the model to examine each drought analysis period, 1977 and 2002 - 2003. Each Demand Scenario includes municipal demand from one Level of Development, as described in the above section, Municipal Uses Within the District, and demands for Snowmaking (at the Snowmass Ski Area), contractual deliveries to Brush Creek Metropolitan District and Wildcat Ranch, and incidental uses including treatment plant backwashing. Each Demand Scenario assembled is described below: 1. Total Existing Municipal Demand With Base Village and Redevelopment. This Demand Scenario includes demand resulting from the Existing Municipal Demand With Base Village and Redevelopment level of Development, and demands for Snowmaking, Brush Creek Metropolitan District, Wildcat Ranch, and incidental uses including treatment plant backwashing. 2. Total District Build-Out. This Demand Scenario includes demand resulting from the Total Build-Out Level of Development and demands for Snowmaking, Brush Creek Metropolitan District, Wildcat Ranch, and incidental uses including treatment plant backwashing. 3. Total Build-Out With Reserve. This Demand Scenario includes demand resulting from the Total Build-Out With Reserve Level of Development and demands for Snowmaking, Brush Creek Metropolitan District, Wildcat Ranch, and incidental uses including treatment plant backwashing. As noted above, a Stream Flow Stewardship Goal of 7 cfs was adopted, and subsequently modeled for each of the three Demand Side Scenarios. Model runs for each Demand Side Scenario and each drought period were initially operated assuming no raw water storage would be available to the District. Subsequently, each Demand Page 16 Side Scenario and drought period were re-run to determine raw water storage volume required for the District to meet demand and maintain (to the extent possible) the Stream Flow Stewardship Goal. The amount of storage required for catastrophic reserve storage is an additional requirement. Page 17 MODELING APPROACH AND RESULTS To assess the impact and benefit of raw water storage, the model was used to examine the impact of increased demand (number of EQRs) on the District's ability to meet demand and Stream Flow Stewardship Goals without additional storage, identify the number of days that shortages would occur, and identify the amount of raw water storage required to minimize or eliminate the shortages. Results were found using the computer model described above. DEFINITIONS FOR MODELING RESULTS The results for the model described above are presented in Tables 3 and 4. The following paragraphs present definitions for the findings. Number of Days District Demand is Not Met: The number of days when the District's maximum physical and legal diversions did not meet the District's demand. This result assumes that Stream Flow Stewardship Goal is missed in order to meet the District's municipal demands. Periods When Demand is Not Met (with No Storage): Date or range of dates when the District was not able to meet municipal demand, for specific EQRs and the Stream Flow Stewardship Goal. It is assumed that the District does not develop any new raw water storage. Amount the District Is Short Each Period: Represents the amount that the Districts physical and legal water supply is short in meeting municipal demand during the associated date or range of dates. Number of Days Stream Flow Stewardship Goal Is Not Met Due to Operation of the District: The Snowmass Creek stream flow below the District's Snowmass Creek pump station was less than the Stream Flow Stewardship Goal due to the District's diversion of water from Snowmass Creek. Page 18 Periods When Stream Flow Stewardship Goal Not Met (District Caused): Date or range of dates when the stream flow dropped below the Stream Flow Stewardship Goal as a result of District diversions. Amount Stream Is Below Goal Each Period: Represents the volume of the stream flow that is below the Stream Flow Stewardship Goal as a result of District diversions. Net Storage Required to Meet District Demand and Stream Flow Stewardship Goal: The net amount of raw water storage required to fully meet the District's demands and eliminate all days the Stream Flow Stewardship Goal is not met due to operation of the District's Snowmass Creek Diversions. Net Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event: The net amount of storage needed to meet the District's in-house demand for three weeks at the particular number of EQRs being modeled. The amount shown reflects an average use per EQR of 275 gallons per EQR per day. Total Net Storage Required: Represents the net amount of storage (excluding seepage and evaporation losses) required to fully meet the District's demands and eliminate all days the Stream Flow Stewardship Goal is not met due to operation of the District's Snowmass Creek diversions, and maintain a storage reserve to meet the District's demand for three weeks for the number of EQRs being modeled. HIGHLIGHTS OF RESULTS The study results are presented in the attached Table 3 for the 1977 study period, and in Table 4 for the 2002 - 2003 study period. Page 19 TABLE 3 DETERMINATION OF REQUIRED RAW WATER STORAGE FOR 1977 STUDY PERIOD Mazimam Non- District Dlwmiom and Tcfs Stream Flow Sta9rerdship Goal MODEL INPUT PARAMETERS District Dim utd: TOW Eciclln Municipt Darr1W With Star Wllege W RoCavNopmem Madrid Demard: ToW gsbicl Build- DUl Dwwkl Demar d: Tool DlsNky sull w With Mwve NumWra EOR5. 5. 900 Number of EORe. SRW Numberd EORa. 6, aW Slra Row slevrrdahv Goad Ids)- T Streem RON Stawrdsho Gosl( ds). 7 Stream Row SlawrWllip Goal( did. 7 Raw W. I. Stwage Availed,( ac-h). 0 Raw Water Straps Avalbbe( acft). 0 Raw Water Storage Availabe( ac-ft)• 0 MODEL OUTPUT RESULTS Dan DwW and Gotha Net Met ton harry Ion Number a Days Districtslricl Deand Not omeed NO 55 Manor of COOa Drneto Not Mal Mal Mal Numbs of Days Slroam Flow Numbr d Days Strwn Row Numb. of Days Soar; Flow Stewardship Goals Are Not MN Dw to 6 Slawrdet0p GoW Me Not Mal Doe to 9 miw of The Dlalnot ya Th. DWrid SlvxMOpft( foals Arco Mal D. b 10 alien d TM Dierks PerioM arW Amaunb a$ hotbpaa Periods Wimm Pariodewim Pielods Wlwn periods Wheh Stream Row Ammem Sown Is Parlode When abeam Row Amount Sbrm Is PaNada When Stbem Row Amowt SOarn Is Demur re Na Amours OlaNb h SWea dswdP GW lialw Goal FSh OemarM b Not Award WMdcl b Sbaard NP GOW Show Geld EaHl Derowel li llet Amount Distrkl is Slwgrdshlp Goal Stalow Goal Each Mat Short Esch Period Not Met Period Wt Short Eaeh Period Not Met Period New Shod Each Period Not Yee Period WIN No Storage) ( cis) IDbtrldt Cembd) ( as) ( With No Storage) ( Ole) ( District Caused) ( ob) tallith No Storage) ( de) ( District Curd) ( cis) 217 to6/ 31 1.6 9// lO 9m 0.2 WIIO B/31 1.a W7 toar9 0.2 flr/ ba/ 31 2.3 W7 to 92 02 911 to9/ 30 0.6 941 WW12 0.2 W1 to ago 0.6 W1110 Wit 0.2 Wt lO Ww 1.2 9/11 to W12 0.2 W15 1n WIG 0.2 W1510 W16 0.2 9115 to Wl6 0.2 12121 0.6 12/21 0.7 12/20 0.1 1221 0.9 1222 0.1 Storage Raqulmnerlb 1) NO Storage etar to Meat District 1) W Storage to lbeat Devoid 1 to DemaM end strwn Flow stewardship 150 are DaneM and Stream Row SbwwdWag 170 acn Damao rd So- rm Flow stwrd 0 210 ac-0 GWS Dismal Goals Distr t Gym Dbtr' 121 Na Storage spared to ' ctrla 2) NO Storage Ruegred N Mm Oil Dann" for 3- wdb DtmrV a 105 w- n Drnrld for3. wsab DOiig a 1t0 ore-it DDernutl Ip S- we ka Dw pa Pe9Ki 120 ac- 11 CmwtmpNc Event Crri cawu Cvrq Galestr Evwd c' Twat Net Storage RoO rsd 255 ac- n Taal NO Storage Reawad Me" Tobl NA StMP Reyired 330 eoh Nor storage hart to Msr Oictna I la 91veaFa " raga tredse b beaad M end Average Ur Par 0U R: 112D0\ 12571257. 00. 0111977 ModehYMa mnum Stream MOdolAslTwe 3 TABLE 4 DETERMINATION OF REQUIRED RAW WATER STORAGE FOR 2002- 2003 STUDY PERIOD 1111111111011m Non- District Diversions and 7< fs Strum Flow Stewardship Goal MODEL INPUT PARAMETERS D1 bl. DrnwW: Total Existing Munklpl DemaW WIm Bm& leaps and Rdevalormtrrt Dim dd Doeoerm: Tom DlshMd Build- Out derriM Dwad: Tool dstrlM BWIdOM N9M Mprva Number of EORa. 5. 900 Numb. of EORs. 62M Numbrof EOM. CM Strum Flow Stawrdahip Goal( do)- 7 Stem Flow Staw' ndsNP Good( do). 7 Shard Flow Stewardship Goal( ds). 7 Raw Wale, Slwago Available( sc-X). 0 Raw Water Slonpe AWlO ( as>10. 0 Raw Water Storage Available( ac-ft)- 0 MODEL OUTPUT RESULTS Days Dsmoad ed Goals NotMat 2002 2003 2002 2003 2002 2003 Number of Day gstnd Derllartl Not 17 0 Number of Day Didnd antl Nd 17 0 Number al Days piatricl Dernantl W- MY met 17 0 Number of Days Sham Flaw Number to Day SbMm Fbw Number Y pay Stream Flow Stewardship Goals Ne Not MY Due to 17 10 SlwwardsNp Gods No NW east D,r to 17 11 Slawrdodip Goals Are Not MN Dw to 25 20 Olwation of The Distntl Oomratw of Th. D'ulritl don of The olstrkv Mods When Swam Flaw Amount Strome, b Mow When Stawm Flow Nnwmt Sown h Period• When Shown, Flaw Amount suamm is demand Is Not Amoonl District is SuwaNship Good Sslaw God Each Dernand Is Not Amermt District Is Stewardship Goal Salaw Goal Fah Dwarf is NM Ammmt Di" is Seamanship Goal Slow God Each Mat Short Each Period Not Mat Mod MN Short Each Period NM MM Period Met Short Each Mod . Not Mat Mod VA1h No Sloroge) ( cta) ( Disbkt Cauad) Ida) Oath NO Storage) ( siq ( Obhkt( awed) ( ds) ( WMh No Storage) ( ds) ( District Cau" m ( cf.) 2/ 27/ 2002 0.6 001] dry0020p2 1.6 2/ 272002 0.] 811741182002 1.8 010002 0.2 9/17- 00182002 2.3 wial 02 0.2 911. 9192002 0.6 W102002 0.1 001- 922002 0.6 2272002 1.0 Wl-& 92002 1.2 3111- 31y112002 0.8 0011- W122002 as 3'11- W142la2 1.0 9111- 00122002 as 3/ 73m120p2 0.2 9111 911T/ 2002 1.2 311 52( 102 0.3 9116. 81172002 0.6 yt/ 10D2 0.1 W169/ 17MM2 0.6 31102002 0.6 9116- 91172002 1.2 8116/ 2002 0.1 921- 912/ 2002 0.6 81162002 0.3 9124- 11rAr 2 0.8 8111- 31152002 1.0 9/24- 912/ 2002 1.2 82W2002 0.1 62812002 0.3 3, 162002 0.1 8/! 1/ 2002 0.1 64112002 0.3 81192002 of 911- SOI2002 1.3 911- 9/ 72002 1.3 81162002 0.6 2242003 03 22112003 0.8 00262002 0.6 22W2000 0.3 72512003 0.1 00312002 0.8 M71MM 0.6 22002003 OA 001- 00)/ 2002 1.3 228- 3122003 0.3 2712003 0.7 12002003 0.2 0032003 3.6 2263/ 22003 0.4 128- 1/ 292003 0.2 320/ 2003 0.1 39203 3.6 1212003 DA 322/ 2003 0.5 32002003 0.6 2/ 12003 0.1 3292003 2.9 12/ 2003 0.6 Wl6/ 200 Do 32002000 3.1 223& 112003 0.2 3202003 0.8 32002003 0.8 3/9/ 1003 3.3 3202000 0.2 Storage iteauhsmenea 1) NY Stwago Required to Most Uchol Demand and Stream Row Stwrandvp 70 clt Drnmm and Shown P. 1) tong mmard ro . Goals D'ulnd Goals Duhid SlwwmdaliP 75 aC6 Dernmld an Sbum Flow Sawrrbfip m cX Goals Sls0 d 2) NY Storage Mmard to Mad ' ctrlol 2) W Slarog, ea Most DstW Demand for 3- wpb Otairg a 105 ac-a Dsmard Iw 3 wwalu Dulo- a 110 and Dwnertl 3- wlo Dung a hxa 120 cX C la Evan Erd Cdea' Cad Total NO Slwaw Roaubtl 175 ao0 TOW Nod Slerepe Regard 165 atrll Tow Not Storage Mpird 200 ca Net Stwpe ROCIMUld m TAM DWrM Hamad Ia 3rwMS a 00101baleso I based M rN Avrpe 1.40 P1w IcENt d 275 gamartt RA12NN125nl 257. 00. 011Sydam Wmand 4 District's Water Storage Requirements. Assuming Maximum Monthly Non- District Diversions and the 7-cfs Stream Flow Stewardship Goal, the analyses indicate that without additional raw water storage the District may not be able to meet the current development commitments and future development demands (Total Existing Municipal Demand With Base Village and Redevelopment, Total Build-Out, and Total Build-Out With Reserve) on a number of days during dry year scenarios similar to 1977 or 2002.Under these assumptions, the District may not be able to meet demand on 55 days during 1977 and 17 days during 2002. During 2003 the District demand could be met everyday. Tables 3 and 4 present these results, a list of the days demand was not met and by how much, and a list of the days the Stream Flow Stewardship Goal was not met and the goal shortage. Descriptions for the results provided in the tables are presented in the above section Definitions for Modeling Results. Tables 3 and 4 also present raw water storage requirements for dry years 1977 and 2002 - 2003 under the three future District demand scenarios (Total Existing Municipal Demand With Base Village and Redevelopment, Total District Build-Out, and Total Build-Out With Reserve). In 1977 the volume of storage required to meet District demand and the Stream Flow Stewardship Goal, as well as maintain three weeks of catastrophic event storage, ranges from 255 ac-it to 330 ac-ft for development levels ranging from 5,900 EQRs Total Existing Municipal Demand With Base Village and Redevelopment) to 6,800 EQRs (Total District Build-Out With Reserve). In 2002 the storage requirements range from 175 ac-ft to 200 ac-ft for the respective development levels. These results are also shown in Tables 3 and 4. Figures 2 and 3 present daily storage utilization for the 1977 and 2002 - 2003 drought periods based on the assumptions of Total District Build-Out, Maximum Monthly Non- District Diversions, and the 7 cfs Stream Flow Stewardship Goal. Figure 2 indicates that in early October of 1977, 280 ac-ft of stored water would have been required to meet District demands and the Stream Flow Stewardship Goal, and maintain the three weeks of catastrophic event storage through the following spring. Similarly, Figure 3 Page 22 Storage Utilization for 1977 Based on 6200 EQRs, Maximum Non- District Diversions, and 7- cfs Stream Stewardship Goal 13 Storage Required to Meet District Demand and Stream Stewardship Goal ( ac- ft) Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event ( ac- ft) 300 Notes:1. Storage Values Shown Are Net of Evaporation and Seepage. 2. Storage Required to Meet District Demand and Stream Stewardship Goal Includes 250 Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event. 3. Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event is based on an Average Use Per EQR ranging from 172 to 275 gallons. 200 w 150 0 of l 100 h r-',. i.. 50 0 m m co m co co co n r. r` r, n n n fl- n N n 1". co 00 ao co . co 00 co C 5 m a t5 > b c - 6 i. Q ( n O Z 0 u- Q Z o - 3 LL 2W CL Q g 5 Month R:\ 1200\ 72577257. 00. 01\ 1977 Models\ Ma> amum System Model. xls Figure 2 Storage Utilization for 2002 and 2003 Based on 6200 EQRs, Maximum Non- District Diversions, and 7- cfs Stream Stewardship Goal Storage Required to Meet District Demand and Stream Stewardship Goal ( ac- ft) O Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event ( ac- ft) 300 Notes:1. Storage Values Shown Are Net of Evaporation and Seepage. 2. Storage Required to Meet District Demand and Stream Flow Stewardship 250 Goal Includes Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event. 3. Storage Required to Meet District Demand for 3 Weeks During a Catastrophic Event is based on an Average Use Per EQR ranging from 172 to 275 gallons. 200 in I w 150 -- Y 100 e-. 50 0 N N N N N N N N N N N CO Cl) M CO CO Cl M M Cl) M Cl) O O O O O O O O O O O O O O O O O O O O C CN l d V N N N N a CC i shows that in early- to mid-September of 2002, 185 ac-ft of stored water would have been required to meet the District demands, goals and provide a storage reserve until the following spring. Note that Figures 2 and 3 indicate the quantity of raw water storage being utilized; the storage supplies shown must be in-place prior to the time when they are indicated to be utilized. Raw Water Storage Sites. The foregoing discussions provide a quantification of the net required raw water storage capacity for the described operational uses. For the purposes of the District and possible additional snowmaking utilization, the storage can be developed in 1 or more sites. Typically the cost of developing multiple small sites is greater than the cost of developing one larger site due to the economies of scale: multiple sites require more infrastructure for water delivery into and from the reservoir, and typically a larger site is more efficient in terms of lower evaporation and seepage losses as compared to multiple sites. Often, however, multiple smaller sites can be developed with lesser impact on the surrounding environment as compared to one larger site. Raw Water Storage Losses. The above quantification of raw water storage requirements does not include consideration of evaporation and seepage losses that reservoir storage water supplies would undergo. Additional storage capacity would be required to store water that would be lost during the period between filling and utilization. District Storage for Catastrophic Events. The analysis indicates that the amount of water needed to meet District demand, for three weeks during a catastrophic event that renders both pipelines unusable, ranges from 105 ac-ft at the 5,900 EQRs development level (Total Existing Municipal Demand With Base Village and Redevelopment) to 120 ac-ft at the 6,800 EQRs development level (Total District Built- Out With Reserve). The required catastrophic storage is based on an average daily use per EQR of 275 gallons, and assumes curtailment of outdoor uses within the District during the emergency period. It should be noted that this magnitude of storage, reserved for a catastrophic event, could sustain the District usage for a period of more than 3 weeks if additional conservation measures, in addition to the elimination of Page 25 outdoor uses, were implemented. Tables 3 and 4 provide estimates of the amount of water storage that would be needed to support the District under the 3 levels of District development if both delivery systems were rendered unusable. Figures 2 and 3 provide a graphical presentation of the catastrophic storage needed on a monthly basis. An examination of the impact to District operations should only one pipeline being rendered unusable, either East Snowmass Creek pipeline or the Snowmass Creek Pump station pipeline, indicates that the District would be able to meet demand, i.e. the District demand does not exceed the capacity of one pipeline (5.1 cfs). This assessment assumes that water is physically and legally available, that during a catastrophic event the delivery and use of irrigation and other outside water would cease, and that the average daily water use would not exceed 275 gallons per day per EQR. Page 26 ADDITIONAL CONSIDERATIONS DOWNSTREAM AND COLORADO RIVER MAIN STEM WATER CALLS During a severe dry year, it is possible that water rights on the Lower Roaring Fork River and the Colorado River main stem downstream from Glenwood Springs would call for water against the District's water rights. These calls could originate from the "Cameo" rights near Grand Junction, or from new diversions under conditionally- decreed oil shale-use rights. .Due to the complexity of the river system, the existing available replacement, and the availability of compensating and offsetting supplies Green Mountain, Wolford and Ruedi Reservoirs), the downstream calls were not considered in these analyses. The District should consider obtaining an "insurance" supply from the United States Bureau of Reclamation (USBR) or the Colorado River Water Conservation District CRWCD) to offset District usage in critical dry periods when the District's water rights could be called out. DISTRICTS RESERVOIR WATER STORAGE RIGHTS The District owns several senior water rights with decrees that provide that "the water may be stored in Snowmass Reservoir". It is assumed that this storage language allows the use of the water rights for storage in any new raw water reservoir(s). The District also owns the Sam's Knob Reservoir water right. In order to provide municipal storage, it is assumed that the Sam's Knob water right could be transferred to one or more water storage reservoirs in the vicinity of the District. WATER SUPPLY FOR AN EXTENSION OF THE SNOWMAKING SEASON The District's snowmaking water rights do not allow for long-term storage. If it becomes necessary or desirable to provide water in long-term storage for snowmaking uses, an alternate source of water would be required. A new junior water right to provide both direct flow water and storage for snowmaking uses would not be expected to produce significant water after December in a dry year. In order to provide an exclusive Page 27 snowmaking water supply to extend the snowmaking season beyond December 31, three options are proposed: 1. Provide raw water storage capacity and an alternate water supply that allows storage and snowmaking uses, and supply the snowmaking demands in the extended season entirely through storage releases. 2. Obtain a new junior water right to allow for the extended season for snowmaking use through direct flow diversions. A junior water right would not be expected to yield any significant quantities of water in the winter during dry periods. 3. Obtain a new junior water right and a replacement water supply such as those available from the Colorado River Water Conservation District CRWCD) or the United States Bureau of Reclamation (USBR) to allow for the extended season for snowmaking use through direct flow diversions. Physical stream flow limitations in Snowmass Creek may preclude the exchange of water up Snowmass Creek in the subject winter dry periods. It is anticipated that either the diversion under a new junior storage water right or the exchange of water to either or both of the Snowmass Creek Pipeline/East Snowmass and Brush Creek Pipeline would only be possible during spring runoff in a dry year. It is therefore assumed that reservoir water would be stored in the spring and held until the following winter for snowmaking uses. QA1200\125T 1257.00.01\061020R_SWSD_Study\061020R_SW SD_Study.doc Page 28 r.epiGl STATE OF COLORADO Colorado Water Conseavatiaa Bwd Depmftnew ofNarm-al Ream =s M 3bm= Dm=.cak=ft» F] am)M&CAct FAX Ot)altt6s"M MEMORANDUM t rsCr cPE 13 q LWC.73 TO: M 19FROM: DATR-- June 25, 1996 SUBJECT: Summary Report and Final Recommendation on Snowmsss Crea=te Modification BACKGRQUE EMRMATTON On January 14, 1976,the Colorado Water Conservation Board(CWCB)appropriated a I2• cfs Watreem flow water right dn Snowmass Creek farm Snowmass Lake downstrem tb its oonfh,e=with the Roaring Fork River. On September 15, 1992,the CWCB ratified amotion to coufoan its Snowr oam Creek itts4eUMIlaw water right to caracot standards by augmenting the 17- mile iastfe m flow reach into tbree shorter stream rraehes and partitioning the 12 efs,yesr-round flow into summer and winter flow emomrb to reflect the biologic flow requirements within tbo three sI segmems(see Snowmass Creek Location Map). On December 9,1992,the CWCB staffand State Attorney General's Office flied for new junior insheam flow water rights to enlarge the Board's summertime inseam flow ruts to 15 cfs and 22.5 cfa within the middle and lower segments of Snowmass Creck,respectively. With regard to stream segments and time periods where the Board determined that less than 12 cfs was required to preserve the natural environment to a reasonable degree,the CWCB notified thu Division Engineer for Water Division 5 @rat it would not enforce the fill amount ofits decreed insheem flow. The Board's decision not tofluty crr tcc its Snowmass Crock instrnmm flow water right was challenged by members of the Aspen Wildemess Workshop(AWW). The Board's decWon was UpWd in Colorado District Court in Case No.92CV6091. However,the District Court's ruling was reversed by the Colorado Supreme Court m Cam-No.93SC740. The Supreme Court's reversal prompted the Colorado State Legslautre to consider 146126on that would co&i r aprocedure for the Board m follow in order to consider decreasing an existiog instrearn flow water right. That legislation,Senate EM 64,was recently signal into law by UovernarRomer. The CWCB la now pursuing a modification ofits Snowmass Creek iosiream flow water right under the provisions ofthat bill. I r.r o ct FpymIGPAA MYER BASALT LOWER SEGMENT SNOWMASS CREEK cPsl a MIDDLE SEGMENT CREEKBantrwl aNOrMAaaVILLAGE ASPEN n b 6 A W UPPER $EGMENT SNOWMASS 9C/ 4/ 4 crs) l SNOWMASS LAKE NORTH LEGEND - SNOWMASS CREEK LOCATION MAP TOWNS AND CITIES NOTE: Segments 004 onoun?. 0s PrMDNTOd SopT2m60r 15. 1992) ' INSTREAM FLOW SEGMENT 2 Tito CWCB conducted a"Preliminary Review ofRequest for Modification on Snewmaw Creek" at its May 14, 1996, meeting in Sterling. At that meeting, the CWCB staff presented evidence indicaliag list the Board's Snowmass Crack inaheam flow water right was based upon a mistake and that it may be==sive. Based upon the evidence presented at the May 14 meeting, the Board_ 1) daterainnod that adequate"Grounds for Modification"had been established, 2) set the"Request for Modification°for final bearing in July 1996, and 3) established fair and formal procedures for the July 1996 hearing. The Board also auixncted staff to meet with rcptescntatives fromthe Aspen Siding Company(ASC) and AWW in an attempt to settle the disputed issues that have arisen with regard to the Board's proposed mstream Sow modification on Snowmass Creel` Mu*--senlar^ant meetings have been primarily focused on the winter$ow requirements within the middle inserea 1 flow segment of Snowmass Creel. Proposed decreases and enlargements to the Board's 12 cfs decreed rostrum flow water right within the other two segtn wA of Snowmass Creek have not bccrr at issue. BIOLOG AND RytML-OG1C REPORTS ON SNOWMASS CREEK AmtmberoMologic and bydrologic reports havebeen gencratedinrespoase to theproposed modification.ofdie CWCB's Snowmass Qvek ioatream flow water right(see attached list). Many ofthese reports ate contained within the administrative record compiled in Case Nos 92CV6091 and 93SC740. Reports notinchrded in the adtttinisuativerecordforCawW s.92CV6Ml aW93SC74q will be [nailed to all Board members under separate cover. The administrative record and the additional reports are avadable for inspeetinn at the office ofthe CWCB. The public is invited to schedule an appointment with the CWCB staff if they would like to inspect or copy any of this information. Sm®ary of CWCB staff memorandum(Esearett_ 19961 The CWCB staff memorandum, entitled "%Wert opinions ramodirig SngMMMs iashum flow Mndifiesgine,is a summary ofthe biologic and hydrologic sports that were received by the CWCB staffprior to Match 1, 1996. Reports and documents received affix that time were not available for inclusion in the staff memorandsm and, therefore,they have been sun narized separatclybrlow. Espegren(1996) summarizes the biologic reports completed by the Colorado Division of Wildlifi:(CROW)in 1992,Chadwick and Associates((badwick!)in 1992 and 1993,WJ.Miller and Amociates(Miller)in 1992,Don Chapman Comsultants,Inc.(Chapman)in 1992,the United States Forest Service(USFS)Snowmass Sin Area Errvimmactital Impact Statement and Record ofDecum PIS and ROD)in 1994,and Walsh Aquatic Comsaltsats(Walsh)in 1995. He also summadm the hydrologic reports completed by the CWCB staff and Wright Water Bnginaers in 1992, the hydrologic studies completed byUSFS in co4unedoa with the Suvwrnass Ski Area HIS in 1994,and stream gaging records that have been collected at the Snowmass Water and Sanitation District SWSD)diversion structure since November 1993. 3 UV.Gl Espegren concludes tbat: 1) CDOW's biologic recommcsidations for modification of the Snowcnass Creek iastream flow water right were based on standard applications of the R2CROSS methodology, 2) the use of"standard setting" medradologies, like RXROSS, are advantageous bermrse they allow the Board to apply imifoaa and condneatbiologic standards to instream flow recommendations on a statewide level, 3) the biologic fnformadw provided in the Chadwick(1992)and Mille(1992)reports support the CDOW's recommendation, 4) the Chapman (1992) tepart indicates that the CDOW's tecammeudations were mathematically co mborated"by the R2CROSS analysis, 5) the Walsh(1995)reportindioam that a flow of 7 of%may not be slffieiertt to provide suitable;conditions for sen wall ofincubatingtrout eggs,and 6) the hydrologic studies completed since 1992 continue to indicate that water is aveiloWe to satisfy the ivatre, flow modifications proposed by the CROW. Sutnmary of CDOW Resort/Skioaer 19961 CDOW's report,entitled"Review ofData and SymgM of%juimts rem{$Snowm cc Creek h1gacadore provides as historic account of the events that led vp to CDOW's recommended biologic msheam flow modiffixtim on Snowrnmm Crock,a description ofthe field data that was used to develop those recozzirimdations,and CDOW's rationale for the teeotsranded modifications. CDO W recommended the foflowing instceam flow modifications in 1992. Table 1.-CDOW Instream Plow Recommendations from 1992- Upper Tc=ms Lava Tevoincs Summer Flow vrw=Flow April 1.Oct.15) Oct 16.Mar_31) C) A) SaMMMa Lake West Sbown=s[reek 9.0 4.0 West Saowrnase Creek Capital Ceeek 15.0 7.0 Capitd Creek Rang Feat River 22.5 11.0 The memo indicates that these recommendations ate based upon a standard RZCROSS analysis and that the proposedmodifications are intended to bang the stteamflows up to current standards by: 1) segmenting the 17-mile long,poring stream reach into three shorter stream segments with more uniform habitat characteristics.and 2) developmg separate flowrecommendations for Bummer and winteswitlim each ofthe new stream segments to mere appropriately address the natural hydrologic chatactmisties ofthe stresmm end the seaamal biologic requirements ofthe fish_ The CROW report sues that the Chadwick(1992)and Miller(1992)studies support and corroborate the results generated by the R2CROSS studies. It WsQ suzanarizes the Walsh(1995) 4 1 L1 report and concludes that while the report`provides some interesting information regarding wild trout populations in Snuwmass Creek ..... he does not propose any alternative flow recommendations in his report nor does be slam that the proposed 7 cfs winter flow xeemmendation will not maintain the existing troat population"- The CROW report is accompanied by a companion report,entitled"Comuntational Pamr which indicates that the Hoard's 12 cis, decreed iastream flow water right is based an a computational error and dial the proposed modifications arc inhadcd to correct that error. Semmm=of ChsdvAck Beport(L2W The Chadwick report, entitled"FiahM and Hjaimum Stream w Tvcm for Sno x-u I=L--,indicates trod: 1) the biomes ofnahaally reproduciug populations ofbrook and browntrout inhabiting Snowmass Creek am below average in comparison with similar Colorado streams, 2) aquatic habitat in Snowmass Creek downstream ofthc SWSD diversion structure is relatively poor, 3) high spring flows we more limiting to the fah populations on Snowmass Creek than winter low flows, 4) 2W aoabraes indicate than a flow of6 cfs would provide adequate habitat levels to maintain trout populations,and 5) a flow of 5.1 cfa saiisfi s the NOW's winter flow R2CROSS criteria within the middle dream reach and therefore the CDOW's proosed winter flow recommendation of 7.0 ch abould provide a suffreiarrt safety margin. The Chadwick report also indicates that the CDOW's RWROSS4nsed iustream flow recommendation of 11 cfs oa the stream segment from Capitol Creek to the Roaring Fork Rives is supportedbytheir ITW analyses. S_nmmsra of welsh Began(1995) The Walsh report,entitled'a Wanter Hwtasty ofTrout inSnowmass QMr,provides shn- speaifie data regarding correlations b"= water velocities and depths over baud redds ("egg nestdI at five stretatrflows(16.2, 13.5, 125,10.7,and 8.9 efs)which were observed over the winters of 1994 and 1995. The report concludes than 1) trout populations in Saawmass Crack are potentially limited by the quality of incobatlon and emelgmae babitst conditions, 2) chanRzs m wakes depth and formation ofanehor ice overrout redds during the winter of 1994 did not seem to be a problem, 3) water velocities over rout redds were significantly lower than published suitable incubation velocities, 4) at a flaw of 8.9 ets,water velocities over trout rodds were significantly lower tlrsn velocities That adult trout selected for spawning, 5) maintaining optimum incubation conditions may negate any recruitment losses during the spring ronoff, 5 P.19/21 6) despite tlm low incubation velocities observed in the winter of 1994 and the Imcueme spring runoff conditions daatg 1995",young-of-tltayew trout fry were observed in September 1995,and i) reductions to redd velocity habitat conditions as a consequence of declining streamflows will proportionally i xmw the ecological risks to the Saowmacs Creek trout population Webb (1996) provides a supplemerttal mwnoraudutn, entitled "Additional data from Snowmass Cffr which summarizes his findings from studies conducted during the 199511996 winter p do& From these additional studies Walsh concludes that: 1) highs flows during rho 1995119%winter period maintained good to optimum trout incubation onditians, 2) in order to preserve water vdioeities within an acceptable tolerance rap(>0.33 8/s) a streamflow of greater than 10 cfs will berequired in Snowmass Creek,and 3) minimum raean incubation flows should be autained at 14 cfs in December, 12 ai3 in January, 10 cfs in February,and 12 eft in March. Summemof Chapman RMO frt190F1 The Chaqunan Rtpoti.wdiiled"Wir>>rr Fmlogy ofTrutfi 1mnL+catians ter Snowmzn Cet W, provides an ecological overview oft o wiener ecology ofttout and the effects ofstream ice on trout habitat The report also critiques the use ofU7DffHABSIM and R2CROSS modeling in streams Brat ezperlerwo overwintet icing imd it raviewa the Montana, Mua&e, United states Fish and Wildlife Service's (USFWS), and State of Vermont's rules for recommending winter flows. Chapmart discounts the use ofthe USFWS's Aquatic Base Flaw yule as unrealis ically high and the use ofVeuna ut's 5 median and Febnrary median roles as too low. He concludaaa that the Mundie and Momaaa rules are most appropriate for Snowmess Creek The Mtmdie rule sttggeats that glow should not be reduced by more than 25%to 304E ofthe saran nXW%ly;flows...,and, on common Sense grounds,not at all in periods ofvery low flows^. The Moat-tor ruk"prehrbits winter water deplattons altogether, These rules result m the following wiener flow reoommendations for the middle segment ofSnowmeas Creak. Table 2.- s Mundu and Mentena Rule Flow Recommendations. Mart Mundie Rule Mooteaa Rote C&) October 22.4 79.0 W vtanber 15.1 22.0 Deamtber 115 MO Jaamray 14.0 14.0 February 13.0 13.0 Minch 12.0 120 6 P.11/21 Chapman concludes that 1) a minimom winter flow of 7 efa falls well below any limit recommended by die above rules, 2) a 7 efs winter rostra flow would reuse the greatest loss ofsuitable conditions over trout redds in Snowmass Crt:ek, 3) because RZCROSS and PHABSIM models use hydraulic simulations and species- specific habitat suitabr7ity otaves that do not acoormt for the ftrificent effects ofice and winter conditions m Snowmass Crock,large impacts should be expected, and 4) adoption of a rainimutn flow calculated by the Mundle mle would result in a stej- down hydrograph w"61 r in shape to thatwhich fall-spawningtrout have adapted and reduce the risk ofacoderstod ice fkms4on while permitting some water withdrawal in November and December. ogre of CROW Letter(81dom r to MerrimaiL Tune 19961 On lane, 17, 1 996, the CWCB staff rocedved a latter Sam Skinner (attached) wNeh ssmtmar= his biologic malream flow recommendations on Snowmass Creek in light of the additional data that has been cella-ted within the middle segment of SaawmwA Creek. Skimmer concludes that•,despite the issues raised by Chapman with regard to modeling sheataflows under winter icing conditions,hydraulic models, Me R2CROSS and PHABSIM, are appropriate and necessary tools for developing imticam flow recommendations in coldwater steams like Snowmass Creek. Skinner believes that the hydraule critmia used by CDOW to develop instream flaw iecommemdeff®s are generally sufficient to preserve the mat in2l environment to a reasonable degree in both the stunwe•and wimmr seasons in eoldwattt at=ms. As such, Skinner confirms that his R2CROSS-based, biological mshestn flow rcomm»dation within the upper segmed ofSnowmass Credo remains at 4 c%,summer.and 4 cfs, winter(see Table 1). Simtlar(y,he confrmrs his previous R2CROSS-based flow recommendations for an enlargement to 15 cfs,summer,within the middle aegamut of Snowmass C=k and for an enlargement to 22.5 efs,summer, and a reduction to 1 t cis, winter,within the lower segment of Snowmass Creek Skinner goes on to indicate that he recognizes the value ofWaWs ante-specific,wintertime data in the developmentof a winter insftem flow recommendation within the middle segment of Snowmass Qeek. Based upon the best available dam,Skinner concludes that a single wintertime flow amount may not be appedptiste for the middle reach of Snowmass Creek. Instead, he recommends that the Board should consider a range of winter flows between 4.99 cfs and 12 ifs within this teach of$a croak, 7 P. 12/21 DISCUSSION Stair sft Inst eam glow p agall The CWCB has met with representatives of ASC and AWW an several occasions to discuss resolution ofthc issues surroundmg the Board's wmz tme 1rstre,m flow wrIhm the middle segment of Snowmasa Creek. As a result ofthese discumns,the CWCB rAffhas developed a multi-stage stair step")instream flow proposal(sea Table 3 and attached gmpbs). The stair step proposal is iatmded to balance ASC's snowmaking needs with AWW's desire to provide the greatest passllle protection for the natural envhoammt an Swwmass Creek. Table 3.-Multi-steze wittierinstmatn flow recommendation on middle reach of Snowmass CtedL 1'C'centile Reeanteeo Iestreem Flow Rec®merdation Water Yaw Ineervel SM%or Cacetet 12 12 efs (10(16-11/30) 10 cfs (1211-3/31) 29th%to 50at"/o IA to 12 12 cis (10116-10131) 10 efe (11/1-12114) 9 c$ (17115-17!31) 10 cfh (211-3131) 1Oth%W 75th% 1:10 to 1:4 la eft (10116-10/31) 10c& (1111-11/14) 9 eft (11/1542121) 85 c$(17112-12/38) Sat (IZQO-1213L) 9 cis (111-3/31) Less than loth% 1:10 9 efs (10116-LORI) Bets (law-10131) 7 cfk (I1/1-1251) fiefs (111-3131) The stair step proposal is mote complicated than a typical single-flow,instream flow water right The proposal consists of four separate, multi-stage inseram flow scemdos that reflect changes in the aatmal hydro"It at low flow recurrence inkmais of 12, 1:4, 1:10,and less Stan 1:10 years. The stair seep frlatream flow proposal incorporates the use of a flow trigger to determine which of the five scoamos would be admhtistaed throughout a particular winter seasou. As proposed,the flow trigger is the average daily flow reading measured at the SWSD weir over the tithe period from October 11 through October 15. Bawd on discnasoaa with Diviafon 5 Erlemer, Odyn Bell,the stair step proposal is administrable ifreal-time gagiM data is available at the SWSD diversion Rttticluta For example, the table at the top ofthe first page of the stair step proposal,labeled"50th Percentile Year or Greater SteitstW',contains streamfluw esdatans and the CWCB's ingtr e3m flaw water right that would be expected to recur within the middle segment ofSnowmase Creek at least S P.13/21 once every two(12)years. Column 1 of that table provides an cstimatc of the undepleted(natural) flow that can be expected to occur at least 50%(1:2)of the time on Snowmass Creek. Undcpletod streamflows (Cohmm 1) are then induced by historic depletions (Column 2)to arrive at current stream flow conditions on the Reek(Column 3). Coltmms 4 through 6 indicate that the CWCB's stair step instream flow water right in 501h percentile or greater water years would step down from 15 cfs to 12 cis on October 15 and then step down again to 10 cis on December 1. The 10 cfs instream flow right wouldthen cantmne throughout the winter mail April 1 when it would step up to the summer flow of 15 cis. A 50th percentile or greater year would be triggered by an average daily flow ofgreater than 29.0 cfs over the period ofOctober 11 through October 15. The graph in the middle of the first page illustsaxs the amount of water expected to be flowing in the creek during a 50dr percentile flow event(from Column 3)and the resulting inatteam flow water right(from Columns 4 through 8). The bar graph at the boamn ofthe page indicates the amount ofwater available for diversion above the proposed instream flow amrnmts(from Couumn 9). The 6 cfs line on the bar graph indicates the amount of water decreed for snowmaking at Snowrnass Ski Area. Bars that exceed the 6 cfs line indicate a Dill supply ofwater for snowmal3ng- The ten sining four pages of the stair step instream flow proposal depict rte streamflow estimates and proposed instream flow watarigbts that would be expected to to=at intervals of 1:4, 1:10, and lea than 1.10 years. Recurnace intervals of IA and 1:10 years equate to "25th" and 10th" percentile low flow water years, respectivety- The graph in the middle of each page illustrates the stneam9ows that would be wtpeceed at each of two reemrnce intervals and the proposed instream flow under that scenario. The graph at the bottom ofcurb page indicates the amount of water available fordiversion. Agaiis these additional stair step proposals are triggered based on the average daily streamflowrecotded over theperiod between October 11 thtougb October 15 at the SWSD diversion structure, The stair smp proposal provides a balance between water development and reasouable preservation of the natural environment. In 50th parole or greater years,the Board's instream Dow water right would step down to a mbh-nw a of 10 efs. As indicated by Walsh,a 10 cfs flow would provide adequate velocities aver trout redder and,as indicated by Chapman,minimi2e the risks oficing. It also provides for full utilisation ofASC's snowmaking system. During 25th%(1:4)and 10th%(1:10)years,the Board's winter insuvarn flows would step down to 9 oft and 9 cfs,respectively. Three two stair stop flow scenarios should be surfficicrt to provide reasonable protection ofthe natural envinmmeat on Snowmass Creek while allowing ASC to fully utilise is snowmaking system through the middle ofDecember in these drier than.average years. While 6 cis may not be available for snowmaking from December 15 through December 31, ASC's projectedneeds$om the Stwwmass Ski Area Eli are fully met during this two week period. The Board's winter instream flaw in extremely dry years,less than 1:10 year rectmena interval,would step down to a minimum of7 cfs_ While the Walsh and Chapman reports suggest that the®pacts oficing cad low water velocities may impact the natural envinsmzd ofSnowmass Creek,these impacts should only oeera infrequently and should not have longterm mrplieations for the tram population in the creek. In addition,while an instream flow of 7 cfs may not allow ASC to divert a full 6 efs supply of water for mowmekiag, it should provide sufficient water to mat ASC's snowmaldrtg demands as projected is the USFS EIS- With few exceptions,the staffa proposed multistage instream flow proposal was acceptable to both AWW and ASC. However,ASC and AWW have am been.able to mumally agreeto support 9 P. 14121 the CPlCB's stair step proposal bwanse they can net reach ag scut on several other overriding wafer use revues within both the Snowurass Creek and Brush Creek drranage basins,some of which arc unrelatod to the Board's proposed mstream flow modification. The staffof the USES has also reviewed the stair step proposal. They believe the stair step proposal is cmtccptually sound and very similar to an early proposal that they considered in the EIS process water Av :1jft SMa9n The CWCB stadl'hm condneted an evaluation ofwater availability for the stream segments. To dry the amount ofwad physically available for the Board's instteam flow appropriations, the staff analyzed available USGS and SWSD gage records, available streamflow models, and utilized standard methods to develop hydnogaphs of mean monthly flows for earl ruommendation. These methods ineludod eatimatess from USGS WRM 854086, correlations by Wright water Engineers and the United Stalm Forest Service (USFS), sport streamflow tneastaemerits, and consultadons with bydrotogists from the USFS and Colorado Division of water Resources. Ilia flaw measurmneots made as part of the various field surveys were also used as an indication ofthe amouru of water pbysically available in each stream segment The staff also analyzed the water rights tabulation within each segment and consulted with the Division S Eaginccr and District 38 Water Commissionerto identify maypotential water availability problems. Based iWun the above analyses and consultations,the ataffconcludes that water is physically available for appropriation on each stream reach to preserve the namral eavkonmem to a reasonable degree without lumiting or foreclosing the exercise of valid existing water rights. STARK RECOMMENDATION The biologic repmffi referenced in the attached list, rebutizia to those reports, and the admioishative record caompiled iu District Court Case No.92CV6091 and Supreme Court Case No. 93SC740 fhrm the tekdtal information available to the Doard. The analysis ofthe best available data gives adequate technical support to the Boards July 1992 decision to"conform"its Snowmass Creek instream flow water right to the Board's current hqueam flow standards. Thaefeao,the staffrecammeuda that the Boatel 1) Dattraing. pursuant to section 37-92-102(3), CRS, and based upon the recommendation oftle CDOW,a review ofthe data and other information presratcd by the staffand others,in this memo and orally,that a) A natraal environment dons exist en each stream segment; b) Water is available in cwh stream segment for appropriation; c) There is a natural cavirotrment that can be preserved to a reasonable degree with the recommaended water rights,ifgranted; d) The astral environment will be preserved to a reasonable deg= by the water available for the recommended appropriations;aad 10 e} Such nanval environment can be preserved without material injury to water rights. 2) Di=the Attorney General's Office to continue to ptasue a decreed iastream flow water right in Case No. 92CW280 for an additional 3 cf% from April t througb October 15,with a 1992 appropriation date on the reach of Snowmass Creekbatweea West Snowmass Creep and Capitol Creek,thereby enlarging the Board's existing 12 eft mfftmtsm flow right to 1S cfe during the summer period. 3) Dir the Attorney General's Office to continue to pursue a decreed instneam flow water right in Case No.92CWZ61 for an additional 10-5 efs,from April l through October 15,with a 1992 appropriation date on the mach ofSnowmaw Creak between Capital Creek and do Roaring Fork River,thereby enluging the Board's existing 12 cfs fnelream flow right to 22.5 cfs during the summer period. 4) p.=ebe CWCB staffand the Aucrocy General's Office to modify,pursuant to the provisions of Senate Bill 64. the CWCB's Snowmass Creek ios4eam flow water right deezved in Case No.76W2943 to 9 es,from April 1 through October 15,and 4 cfs,from October 16 through Mareb 31,an the reach ofSnowmass Crack between Snowmass Lake and West Snowmass Creek. 5) jet the CWCB staff andthe Attorney Ganaul's OfEca to modify,pursuant to the: provisions of BiII 64, the CWCB's Snowmass Creek insst cam flow water right detaxd in Case No.76W2943 to the dtair step recommendations proposed by the CWCB staff on the reach of Snowmass Creels betwech West Snowtnsss Credo and Capitol Crock 6) V!=dw CWCB staffand the Atnmrey General's Office to modify,pursuant to the provisions of Senate&1164, the CWCB's Snowman Creek instream flow water right deureai in Case No.76W2943 to 11 efs from October 16 through Mn-.h 31,on the reacb of Snowmass Croak between Capitol Creek and the Roaring Fork River. DCWGDE Attachments aseuaervarlutyull 11 N.. . a . . . : nun: Lj! .• a/ u . q>yy. J M77MMM w r . N c r -r r. , •. r n•p -11} Ne id•.:1 v.rp ul . tf : . .I. . I 17:._1 • • J 11-6 1. r }.77M._ i•JC xl - •) a X11 p•.:1. w(_.. rTm r .r . . 1 9\ :q • u Py1 •, zH _i u 7 . V: U n• • LI i. .; .. - rl i U J'i 4it i• a •11' 777,4N . _ all 1/ !ir••!1',• a Fr ,1 •LLTrALM P..I;- Jl• '1JL;r' = o : un.l rM 1 1 YI P-774 r 1 ... . y . 1l•: 1 111• V• ' •J `1r• Ai r.lc a . . ` u= :. n •i . a . r.. • N ..n. mr : I .: N..a. .1 . .'I vnc . : n 1 ypiJ.m.., `1J _ ' . :..7•.n " r • • . _._. l?ref 1L a7 1!1 JV.. J1 s•ISLL' , u . v: .. 1.1.a-. q . 1.. :n • r 1 th,r P.18/21 STATE OF COLORADO n um To Hoy Romer,6ovcm0, DEPARTMMT OF KATURAL RMOURCES gyp DIVISION OF WILDLIFE rwrnuaLarPOyLUMrrrevlDL John W.Mumma.Director ago BroallwaV De"W.0010172OC 5sre40DO QF Teteor=Q:6031197.1197 For Mffife-- fvr People 17 June 1996 Dan Merriman, Chief Water Rights InvestigaLions Section Colorado Water Conservation Board 1313 Sherman Street, Suite 721 Denver, Colorado $0203 Subj: Snowrmass Creek inatream Flow ModiScittion Dear Dan: The purpose of this letter is to update the report prepared 29 February 1996 and state the final CDOW recommendation concerning the proposed modification ofthe Snowmass Creek instream 11ow right. In reaching the recommendations set forth in this letter, CDOW relied primarily on R2CROSS modeling results although the CDOW recommendations for Snowmass Creek are not based entirely on this methodology. As stated in the Division`s 29 February 1996 repcut,the Division applies three hydraulic criteria to a R2CROSS stagingtable to recommend instteam flows to the Colorado Water Conservation Board, Summer instream flow recommendations arc developed by selecting a (low which meets all throe of these hydraulic criteria and winter flow recommendations are developed by selecting the flow which meets two of these criteria. The summer flow recommendations for Snowmass Creek that have been advanced by the Division of Wildlife have not ben challenged by any of the parties. The upper reach of Snowmass Creek (from the headwaters at Snowmass Take to the confluence with West Snowmass Creek) bas not been the subject of a great amount of controversy. the Division's previous letters and reports Contain our recommendations of the flows necessary to preserve the natural environment to a reasonable degree. The only studies that have been conducted in the upper segment are the 1975 studies by the Division of Wildlife. The ins ream flow recommendation for the upper reach of Snowmass Creek is 9 efs from Apri) 1 through October 15 and 4 cfs from October 16 through March 30. The winter flow recommendation in the middle segment of Snowmass Creekbas been the subject DEPARTMENT OF NATURAL RESOURCES,Jwaee S.Lochhead,Fseoutive Direernr YALDLjFE COMMISSIOW Amold Salazar,Chdrman•Robe Frar*r Mea Chalr•Mwk LeVnGay,Beeranary Jos.1."idaa Boyd,Jr.,Mentor• Chuct Lewis,Member Jahn 8001),Member•Laub F.9w9L Member-Jana R.Lang,LY Mbar P.19/21 Letter —Dan Merriman,CWCB Snowmasx Creek lnstream Flow Modideation 17 June 19% ofmost of the controversy in this case. The middle segment has been defined as the reach from the confluence with West Snowiness Creek down to the confluence with Capitol Creek.It has been in this segment where all of the consultants have:directed their studies. Table 1 in the N February 1996 report displays the flows at which the'criteria are met at the five R2CROSS cross sections in the middle segment of Snowmass Creek. The R2CROSS modeling at the five sites in the middle segmmew ofSnowiness Creek indicates that two hydraulic criteria am met at flows bemreen 4.99 cfs and 10.72 cfs. In the 29 Febnraty 1996 report and the 1992 letters from the Division to the CWCB referenced in the 29 February 1996 report), the Division's opinion was that the winter instrcam flow recommendation should be increased from 5 cfs to 7 ch to add a margin of safety due to shallow water depths at 5 cfs. As will be explained below, inforoation developed by other consultants has been considered and evaluated and after considering all available information Concerning the middle segment,the Division's winter time instream flow recommendation is that a range of flows from 7 cfs to 12 ch(depending on the type ofhydrologic year being experienced) is needed to prescrve the natural environment to a reasonable degree. Like the upper segment,fire flow recommendations for the lower segmmt of Snowmass(?reek(from Capitol Creek to the Roaring Fork River)have not been challenged.The only studies that have been conducted in fins segment are those conducted by the Division ofWildlife in 1992. the Division's flow recommendations based on the R2CROSS modeling remain at 22.5 cfs for April 1 through October 15 and l l cfs for the remainder ofthe year(see.Table I of 29 February 1996 report)_ Since the production ofthe 29 February 1996 report, a number of things have occurred. Don . Chapman Consultants,Inc.has produced two reports,"'Winter Ecology of Trout:Implications for Snowmass Creek" and "Revised Stream Habitat Survey of Snowmass Creek, Colorado". Earth Resource Investigations,Inc.has produced a collection ofphotographs bound into a document, "Is Snowmass Creek Blown Out? The Following Photos Show High Quality Aquatic and Riparian Habitat on Snowmass Creek". And on 15 March 1996, a meeting ofall the biological consultants was held at the offices ofthe CWM At this meeting, all ofthe consultants desan'bed their studies and conclusions and openly questioned one another about their methods and opinions. At this meeting, I gained a greater understanding of the Walsh study, "The Winter Ecology of Trout in Snowmass Creek,Colorado" and the investigator's specific concerns during the winter months. I gained some understanding ofthe Chapman winter ecology report as well (the habitat survey was not provided to the group until after the 15 March meeting). The Chapman winter ecology report contains no data specific to snowiness Creel:. The report describes wintertime behavior oftrout,habitat selection, and mortality,and the physical processes of ice formation in streams.These are biological and physical processes that are widely accepted and are supported in the scientific literature. Chapman criticizes the use of both R2CROSS and IFBkPHABSIM to develop insueam flow recommendations on ice covered streams. I-Ie proposes the use ofthe"Mundie Rule"which is best described as a rule ofthumb in which flows should net 2 H.20121 Letter —Dan AMnTiman,CWCB Snewmass Creek Instream Flow Modification 17 June 1996 be reduced by more than 25%to 30%ofmean monthly flows and in very low flow situations, flows should not be reduced at all. This "title" is nothing but a single sentence taken out ofa nine page paper that facuses on mitigation opportunities in regulated Pacific coast rivers. It seems contrary to reason that one should ignore site specific-daa.and widely cued and accepted instream flow methodologies in favor of one senwee taken out ofcontext. As a result of the 15 March 1996 meeting and a mots careful reading of the Walsh report,I am of the opinion that there is some useful information contained in the report that is relevant to winter inslream flow recommendations on Snowmass Creek. Walsh conducted studies in the middle segment of Snowmass Cmck during the winter of 1994-95. He identified over 30 redds, marked thern and measured water depth and velocity at five positions at each redd over the winter season. Streamflows(mean monthly)over this period varied from 169 cfs to 103 cis with mean daily flows varying from 19.1 efk to 8.6 cfs. Inslantancouz flows during the study period were measured as low as 5.1 cgs. Depths and velocities al each redd were measured as streamflows dropped through the winter months. Over the wiM=,the redd pit velocity fell from 0.71 fedIsec(fps)to 033 fps and add tailspill(where the incubating eggs are located)velocities fell from 0.92 fps to 0.47 fps. These are men at-point values at actual trout redds in Snowmass Creek where the velocity values used in the R2CROSS analysis are mesa values across a stream cross soction that are calculated using the Manning's equation. In Walsh's opinion,these reductions in velocity at the individual redds are at or tear the threshold ofacceptability and any fin-ther reduction in flow would impact the fishery in Snowmass Creek. The literaurre suggests that R2CROSS may overestimate actual stream velocity in some circumstances.Nehtmg (1979). This observation seems bom out in the site-specific information set forth in the Walsh report, and therefore use of the 1.00 fps average velocity criterion on an R2CROSS cross section may provide actual stream velocities less than 1.00 fps_ Table 1 of the Division's 29 February 1996 report shores thst at four ofthe five R2CROSS cross sections in the middle segment during the wiaW time period(the time theu,only two ofthe three hydraulic criteria are met)the IA0 fps average velocity criterion is either the threshold for the recommendation or it is not met The site specific Walsh iufoamationtherefare leads the Division to believe that a straight line flow of 7 cis during the winter months may not be sufficient to provide long term preservation ofthe natural environment of Snowmass Creek- For that mason,satisfaction of2 of3 criteria in the middle reach of Snowmass Creek may not result in the minimum flow necessary to preserve the natural environment to a reasonable degree_ The 4.99 cis to 10.72 cis range indicated by the 112CROSS method should be expanded up to approximately 12 cfs to provide the needed winter protection for egg ineubadon in Snowmass Creek. It is impazwAto stress the continued confidence that the Division ofWildlife has in the R2CROSS methodology. R2CROSS is not unlike any other model in that all computer models have their critics and shortcomings. Mary ofR2CROSS's limitations have been known since Colorado started 3 I G1 Gl Letter —Dan Merriman,CWCB Snowmass Creels Instream Flour Modillcation 17 Jane 19% using it in the 1970's. The Division remains of the opinion that hydraulic models like R2CROSS and EFDATHABSIM have their place in recommending instream Rows in Colorado. R2CROSS remains as the primary tool used to quantify instrrsrm flow amounts in most Colorado streams. The 1FINVP'HABSIM insltt am flaw methodology will also be utilized by the Division in circumstances which warrant its labor intensity, tune commitment, incremental featurus, and complexity. The instream flow recommendations for Snowmass Creek contained in the 29 February 1996 report and this letter rely on the results of 112CROSS with confirmation from PHABSIM The winter and summer flow recommendations for the upper and lower segments and the summer flow recommendations for the middle segment rely on the R2CROSS results exclusively. The site specific information relating to the fail, winter, and early spring nWm-A environment's flow requirements found in the reports provided by the other parties in this case in addition to the extensive R2CROSS sites in the middle reach all contributed to the Division's flow recommendations. Pleasc feel free to contact me if you have any questions or concerns regarding these recommendations. Suuetely, q PbYW si ResearcherlScientist III CDOWbgrearn Flaw ProgramCowdin Ur JWSfjayrcba617 4 TOTAL P.21 STATE OF COLORADO Colorado Water Conservation Board PtEa CO sFR` Department of Natural Resources o a 1313 Sherman Street,Room 721 sDenver,Colorado 80203 o P Phone:(303)866-3441 FAX:(303)866A474 www.cwcb.stale.co.us 1 9 31 Bill Owens Governor Russell George October 29,2006 Executive Director Rod Kuharich Mr. Alan Martellaro CWCB Director Division Engineer Dan McAuliffe Water Division No. 5 Deputy Director P.O. Box 396 Glenwood Springs, CO 81602 Dear Mr. Martellaro: As you are aware, the Colorado Water Conservation Board (CWCB) modified its Snowmass Creek instream flow water right in 1995. As a part of that modification, it was determined that the Board's wintertime instream flow right within the middle segment of Snowmass Creek, from West Snowmass Creek downstream to Capitol Creek, would be allowed to vary between years based on a defined streamflow trigger. The streamflow trigger was defined as the average daily streamflow over the 5-day period from October 11 through October 15 ofeach year. Since the modification, the CWCB staff has worked with the Division 5 Engineer's Office to install a new satellite monitoring station within the middle reach of Snowmass Creek. This station is located near the Snowmass Water and Sanitation District (SWSD) diversion structure. The purpose of this gage is to help in the administration of the Board's instream flow right on Snowmass Creek. The October 11-15 average streamflow for Snowmass Creek in the vicinity of this gage was 45.5 cfs. The CWCB's streamflow trigger was based on a hydrologic model of Snowmass Creek that was depleted by 2.0 cfs to reflect historic diversions at SWSD's East Snowmass Creek diversion structure. The average diversions at the SWSD's East Snowmass Creek diversion structure during this year's 5-day trigger period appear in Column 4 of the table below. Column 5 of the table reflects an adjustment to the measured flows to account for the hydrologic model and East Snowmass Creek diversions. The trigger flow arrived at by this method is based on adding the actual amount of water diverted from East Snowmass Creek back into the measured flows to obtain a "natural hydrograph" and then subtracting out the 2 cfs historic diversion that was assumed in the model. Therefore, the average daily streamflow in Snowmass Creek during the trigger period was calculated as 45.3 cfs. I 3 4 5 Date Measured East Snowmass Creek Adjusted Discharge cfs Diversions * cfs Discharge t cfs Averages 45.5 1.84 45.3 1 Column 5 =Column 3 +Column4—2cfs 2 *East Snowmass Creek Ditch and Pipeline average diversion over the 5 day period The CWCB staff concludes that the best available data indicates that the average daily streamflow for the 5-day period from October 11, 2006, through October 15, 2006, as adjusted for diversions on East Snowmass Creek, was 45.3 cfs. This trigger flow falls within the range of the flows indicating a "50th Percentile Stair step". Based on this analysis, the CWCB requests that its winter instream flow water right within the middle segment of Snowmass Creek be administered as follows: Flow cfs Date 12 10/16- 11/30 10 12/1 —03/31 Sincerely, Q. ^ CO. Jeff Baessler, Senior Water Resource Specialist Stream and Lake Protection Section Colorado Water Conservation Board cc: Dan Merriman George Ware Mark Uppendahl Sue Helm Dean Wieser Flood Protection•Water Supply Planning and Finance•Stream and Lake Protection Water Supply Protection•Conservation and Drought Planning Snowmass/Capitol Creek Caucus A non-profit corporation protecting the fragile ecology Ofone of Colorado's most beautiful mountain valleys. January 23, 2007 DELIVERED BY HAND Dave Spence, Chair Board of Directors Snowmass Water and Sanitation District P.O. Box 5700 Snowmass Village, CO 81615 Dear Dave: As you know, we were pleased to receive and review last Fall the "Dry Year Yield Analysis". report by W.W. Wheeler and Associates. And we commend the District for moving forward with its commitment to raw water storage — hosting the Special Meeting with Town officials and interested parties on January 25th working diligently to secure a reservoir site; and increasing system development fees earmarked for storage in the adopted Budget for 2007. When we spoke by telephone last week, it became apparent that while you welcomed the support of the Caucus in engendering community backing for storage and in securing regulatory agency approvals, you were not prepared to consider comments or questions on the 7 cfs streamflow stewardship goal. As I indicated, we will respect your request that the 2-hour Special Meeting this week not become the forum for dueling opinions or experts on minimum streamflow science or law. We will submit the attached Statement for the record and offer comments that are short and to the point. Ifwe don't do this, who will? Snowmass/Capital Creek Caucus is a 501(c)(3) organization. Your contribution is tax deductible. P.O. Box 507. Snowmass CO 81654 Recycled paper 1, . 4 ti However, while we are thrilled by the prospect of raw water storage being added to District infrastructure, we are concerned that the District will continue to rely on the Wheeler report's suggestion that a voluntary Streamflow Stewardship Goal of 7 cfs will adequately protect Snowmass Creek. While water law gives the District the right to select a static 7 cfs and label it a stewardship goal, aquatic science to date indicates that 7 cfs is inadequate to protect the resource. Instream Flow As you know, the established CWCB minimum stream flow for Snowmass Creek, between the District pump station and the confluence with Capitol Creek, is set each Fall and fluctuates with natural conditions. All studies have shown that a static 7 cfs will not protect the creek. Indeed, when in 1992 the CWCB reduced the msf for Snowmass Creek from the value set in 1976 of 12 cfs down to a static 7 cfs, that decision was overturned by the Colorado Supreme Court in 1995. As a result, a new procedure was adopted by CWCB to change msf. Through this procedure, a new multi-stage msf was adopted by the CWCB in July 1996, taking into consideration water availability, biological information that had been gathered during the four intervening years, and the needs of the major water users. To balance these considerations, four multi-stage instream flows were proposed by the staff of the CWCB and DOW. With refinements, this methodology was accepted and the new variable msf was adopted by the Water Court. Attachments A and B are that Order and the related CWCB Memorandum. As noted, utilizing this approach CWCB establishes the msf in the Fall. Thus, the current msf for Snowmass Creek is not a static 7 cfs but rather was 12 cfs until November 30, 2006 and then 10 cfs until March 31, 2007. (See, CWCB letter, Attachment C). By comparison, the mid-winter msf in 2006 was 9 cfs. Only in the rare event of a less than 10% dry year would msf be as low as 7 cfs. Operational Issues You indicated a willingness to engage in informal dialogue with Caucus representatives on ways to support raw water storage. I indicated that in addition to our consultants at Hydrosphere Resource Consultants, perhaps other consultants could become a resource as operational details of an agreement to utilize Lake Deborah is worked out. 2 1 The goal of the Caucus has long been to insure that bypass flows at the Pump Station adhere to CWCB fluctuating minimums except in emergencies. Participation and input as operating agreements are fashioned could well achieve that goal. If there is any question in your mind on the need to protect the Creek to the msf level, we would be glad to bring a summary of the science and discuss the rationale for the Snowmass Creek msf with the Board. This could be done informally with you and Kit Hamby or in 20 minutes at a Board meeting. We reiterate our commitment to supporting the District in its efforts to implement adequate raw water storage. And we look forward to participating in the joint public meeting with the Town at 9:00 a.m. this Thursday. We share the community-wide interest in both a reliable water system and one that adequately protects and conserves the natural resource. Very sincerely, SNOWMASS-CAPITOL CREEK CAUCUS Tidy Project Coordinator cc: All District Board Members Kit Hamby, SWSD Manager Doug Mercatoris, Mayor, Town of Snowmass Village All Town of Snowmass Village Council Public Counsel/Securing Snowmass Streamflow/SWSD Board of Directors 1'20'07.doc1tr 3 DISTRICT COURT, WATER DIVISION 5, COLORADO Case No. W 2943 ORDER DECREASING INSTREAM FLOW DECREE IN THE MATTER OF THE APPLICATION FOR WATER RIGHTS OF THE COLORADO WATER CONSERVATION BOARD ON BEHALF OF THE PEOPLE OF THE STATE OF COLORADO, IN SNOWMASS CREEK, A NATURAL STREAM, IN THE WATERSHED OF THE ROARING FORK RIVER, IN PITKIN COUNTY, COLORADO. On July 15, 1996 , the Colorado Water Conservation filed with the court, its notice of final written determination regarding the decrease of the instream flow decreed in this case. No petitions for judicial review have been filed with the court within the time allowed by § 37-92-102 (4) (b) (III) , 15 C.R. S. (1996) . The instream flow appropriation on Snowmass Creek is decreased as set forth below: 1 . On the reach of Snowmass Creek between Snowmass Lake and West Snowmass Creek, the CWCB' s Snowmass Creek instream flow water right decreed in Case No . W-2943 shall be reduced to 9 cfs, from April 1 through October 15, and 4 cfs, from October 16 through March 31 . 2 . On the reach of Snowmass Creek between Capitol Creek and the Roaring Fork River, the CWCB' s Snowmass Creek instream flow water right decreed in Case No. W-2943 shall be reduced to 11 cfs from October 16 through March 31. 3 . On the reach of Snowmass Creek between West Snowmass Creek and Capitol Creek, the CWCB' s Snowmass Creek instream flow water right decreed in Case No. W-2943 shall be reduced to one of the four multi-stage instream flows depicted in Table 1 (below) during the period from October 16 through March 31 of each year. Determination of the multi-stage instream flow that is to be use throughout the October 16 through March 31 period shall be predicated on an instream flow trigger which is defined as the average daily stream flow from October 11 through October 15 of each year. In addition to the multi-stage instream flows described above, the CWCB' s instream flow within this reach of Snowmass Creek will also be administered so as to provide additional protection following extremely dry periods, identified by the occurrence of three consecutive "less than 10th percentile years" as defined in the Table 1) . Following such extremely dry periods, a "recovery year" will be provided in which the stream reach will be administered using the 1150th percentile year or greater" multi-stage instream flow, regardless of the instream flow trigger in the recovery year. within this middle segment of Snowmass Creek, daily administration of the multi-stage instream flow shall include a certain degree of flexibility between November 15 and December 21 of each year. Specifically, during this time period the multi- stage instream flow will be administered based on a 24-hour, rolling average and for periods of no more than 6 hours in any 24-hour period, junior diversions will be allowed to instantaneously reduce the flow in the creek below the multi- stage instream flow amounts by up to 2 cfs provided that : a) at no time will such junior diversions cause the stream flow to fall below 7 cfs, and b) at no time will the 24-hour rolling average fall below the multi-stage instream flow amounts . The multi-stage winter instream flow is specific to the facts and situations encountered within this middle segment of Snowmass Creek and shall not be applied to other reaches of Snowmass Creek or to any other instream flow filing. Table 1 . - Multi-stage winter instream flows on the reach of Snowmass Creek between west Snowmass Creek and Capitol Creek . Percentile Predicted Recurreaee I"stream Flow Trigger Multi-stage Insrream Flows Water Year Average daily stream flow,f om October Interval I1 through October 15) 50th%or Greater 1:2 Greater than or equal to 29.0 cfs 12 cfs (10/16-11/30) 10 efs (12/1-3131) 25th% to 50th% 1:4 to 1:2 Ut char 29.0 cfs and 12 cfs (10/16.10131) Greater than or equal to 27.0 cfs 10 cfs (11/1-12114) 9 cfs (121L5.12131) 10 cfs (1/1-3131) 2 loth% to 25th% 1!10 to 1:4 Tess than 27.0 cfs and 12 dfs(10116.10/31) Gmater than or equal to 19.0 cfs 10 cfs(11/1.11/14) 9 cfs(11/15-12/21) 8.5 cfs(12/22-12/28) 8 cfs(12129-12/31) 9 cfs(111.3/31) Less than 10th% 1:10 Less than 19.0 cfs 9 dfs(10116.10121) 8 cfs(1022.10/31) 7 cfs(1I/1-12/31) 8 c&(111-3/31) The effective date of the decrease was July 9, 1996. DATED THIS DAY OF 1996 BY THE COURT Thomas W. Ossola Water Court Judge Water Division 5 State of Colorado 3 SnowmasslCapitol Creek Caucus A non-profit corporation protecting the fragile ecology Ofone ofColorado's most beautiful mountain valleys. SPECIAL MEETING OF THE SNOWMASS WATER AND SANITATION DISTRICT JANUARY 25, 2007 STATEMENT REGARDING THE NEED FOR RAW WATER STORAGE TO PROTECT MINIMUM INSTREAM FLOWS AS WELL AS TO IMPROVE THE RELIABILITY OF THE MUNICIPAL WATER SUPPLY The Snowmass-Capitol Creek Caucus supports with enthusiasm the District's commitment to secure raw water storage. The Caucus pledges its cooperation in implementing one or more storage reservoirs, subject however to three provisos or conditions: (1) the storage has sufficient capacity to protect environmentally and scientifically recognized minimum stream flows (m.s.f.) on Snowmass Creek as well as to improve the reliability of municipal water supplies for Snowmass Village at times of peak demand or catastrophic event: (2) the District pledges to use that storage to respect and bypass the m.s.f. except in the event of emergencies: and (3) the District pledges its cooperation to consider, and to accommodate when warranted, the views of all interested parties in determining the amount of storage needed, including discussion and interchange of ideas between its consultants and advisers and the consultants and advisers of other interested parties. If we don't do this, who will? SnowmasslCapitol Creek Caucus is a 501(c)(3) organization. Your contribution is tax deductible. P.O. Box 507, Snowmass CO 81654 Recycled paper