STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES

Transcription

1 STATE OF CALIFORNIA DEPARTMENT OF WATER RESOURCES ANNUAL INVENTORY OF WATER USE LAKE TAHOE & TRUCKEE RIVER BASINS Calendar Year 2016

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3 STATE OF CALIFORNIA Edmund G. Brown, Jr., Governor CALIFORNIA NATURAL RESOURCES AGENCY John Laird, Secretary for Natural Resources Department of Water Resources Grant Davis Director Cindy Messer Chief Deputy Director Eric Koch, Deputy Director (Acting) Integrated Water Management Arthur Hinojosa, Chief Division of Integrated Regional Water Management Gary Lippner, Chief North Central Region Office ANNUAL INVENTORY OF WATER USE LAKE TAHOE & TRUCKEE RIVER BASINS Calendar Year 2016

4 Preparation Team California Department of Water Resources North Central Region Office Regional Planning and Coordination Branch California Nevada & Watershed Assessment Section: Gary Lippner, P.E, Office Chief Amardeep Singh, P.E., Branch Chief Paul R. Larson, P.E., Section Chief Tom Scott, Engineer, W.R. David Willoughby, Engineer, W.R. Office of the Chief Counsel: Linda Ackley, Senior Attorney

5 Executive Summary The Lake Tahoe and Truckee River watershed basins are shared between the states of California and Nevada. This annual inventory of water use reports the quantity of water used from surface water and groundwater sources within the California portion of these two watershed basins during the calendar year of record, This report is compiled annually and submitted to the Truckee River Operating Agreement (TROA) Administrator to comply with the interstate water allocation requirements of Public Law (PL) , Section 204(d), and further defined in TROA. This 2016 Annual Inventory of Water Use report is the first such annual report produced since implementation of TROA in December Also included in this report is an estimation of the total amount of water depleted from California s Truckee River Basin in accordance with the depletion calculation requirements defined in TROA. Depletion refers to the amount of water that is used or consumed, but is not ultimately replenished into the watershed s streams or groundwater aquifers through percolation, treatment, etc. The maximum depletion criteria defined in TROA only applies to water used in the Truckee River Basin. The primary source of potable water within the Lake Tahoe and Truckee River basins is from groundwater. While the public water purveyors supplying the communities of Kings Beach, Tahoe City, Tahoma, Homewood, South Lake Tahoe, and the Town of Truckee are the largest significant users or distributers of water within the basins, this report also quantifies the amount of water used by private single family dwellings, multi-family and commercial developments, golf courses, and other public agencies serving smaller developments or local amenities, including campgrounds, trailer parks, and small shared community systems. The quantity of water used for snowmaking is also reported in accordance with PL and TROA. California s total annual allocation from surface and groundwater sources within the Lake Tahoe Basin is 23,000 acre-feet. The total annual allocation from Truckee River Basin sources for use in California is 32,000 acre-feet, of which no more than 10,000 acre-feet can be from surface water sources. Additionally, the calculated annual depletion within the Truckee River Basin must not exceed 17,600 acre-feet as determined by depletion calculations prescribed in TROA. These allocations were originally determined by the California-Nevada Interstate Compact Commission and ratified by California and Nevada in 1970 and 1971, respectively, but were never formally approved by the United States Congress. In 1990, PL was passed by Congress and signed by the president; however, it required that certain conditions be satisfied prior to the California-Nevada interstate allocation mandate becoming effective. The final condition was satisfied 25 years later with the official implementation of TROA in December 2015, thereby effectively establishing the interstate allocation and the reporting requirements described above. Total Reportable Water Use for 2016: The total reportable quantity of water used by California interests from the Lake Tahoe Basin in Calendar Year 2016 totaled 11,950 acre-feet, the equivalent of 52 percent of the allocation of 23,000 acre-feet. The total reportable water used by California interests from the Truckee River Basin for Calendar Year 2016 totaled 8095 acre-feet, or the equivalent of 25 percent of the allocation of 32,000 acrefeet. Of this total, 310 acre-feet was reported to be diverted directly from surface water sources, or 3 percent of the allowable maximum limit of 10,000 acre-feet. The total reportable water usage within the Lake Tahoe and Truckee River 1

6 basins by California interests for Calendar Year 2016 is summarized in Table 1, below, and further described throughout this report. Table 1 Summary of California s 2016 Reportable Water Use for the Lake Tahoe and Truckee River Basins Manner of Use Lake Tahoe Basin (acre-feet) Truckee River Basin (acre-feet) Total Water Use Surface Portion Municipal & Industrial (Includes private domestic wells) 11, Golf Course Irrigation 500 1, Snowmaking Total Reportable Water Use for ,950 8, Total Annual California Allocation per PL % of Total Annual California Allocation 32,000 23,000 (Total Water Use) 52% 25% Up to 10,000 maximum from surface water sources Total Truckee River Depletion for 2016: Based on the water usage data provided and other applicable data, either reported or estimated, the total Truckee River depletion for 2016 was calculated to be 2,810 acre-feet, or the equivalent of 16 percent of the allowable annual depletion of 17,600 acre-feet. The Truckee River total annual depletion calculation process is described within this report. This water use inventory describes the reported water usage quantities noted above and includes water usage quantities reported to the California State Water Control Board based on its current reporting requirements or reported directly to DWR to assist with this report. Existing domestic well information was obtained through document research conducted by DWR, generally using information provided previously by permitting agencies located in the four major counties situated within the basins; Placer, El Dorado, Nevada and Sierra Counties. While Alpine County occupies a very small part of the southern end of the Lake Tahoe Basin watershed, this alpine area is very remote and no diversions or water consuming developments have been identified or reported for this area. 2

7 This annual report also identifies new non-exempt groundwater wells that were constructed in the Truckee Basin during the year of record. These wells are typically permitted by the local permitting agencies within the applicable county and then reported to the State. During the 2016 calendar year, there were no such non-exempt wells reported to the state. Upon the implementation of TROA in late 2015, a water use inventory is now required to be prepared by California and Nevada for every calendar year and provided to the TROA Administrator by the end of the following third quarter (September 30). It was agreed by the TROA Administrator and the states of California and Nevada that calendar year 2016 would be the first year reported. It is anticipated that the accuracy and reliability of this annual inventory and the related water usage data related to California diversions, distribution sources and their respective annual uses will continue to evolve and be refined in subsequent years as additional information regarding existing inventories, their respective water use, metering and sewering methods, and reporting methods are improved. 3

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9 Table of Contents Executive Summary... 1 Table of Contents... 5 Tables... 5 Figures... 5 Introduction... 7 Authority... 9 Background Compliance with Public Law and TROA Water Use Inventory Municipal and Industrial Use Private Domestic Wells Water Purveyors Properties Not Connected to a Metered Domestic Water Distribution System Water Use for Golf Course Irrigation Additional Water Use for Irrigation in Lake Tahoe and Truckee River Basins Water Used for Snowmaking Truckee River Total Depletion Calculation Assumptions APPENDICES APPENDIX A Select PL Sections Related to Interstate Allocation Compliance APPENDIX B Select TROA Sections Related to Interstate Allocation Compliance APPENDIX C 2016 Water Use Tables APPENDIX D Inventory of New Non-Exempt Wells constructed within the Truckee River Basin during Tables Table 1 Summary of California s 2016 Reportable Water Use for the Lake Tahoe and Truckee River Basins... 2 Table M&I Water Diversions Chargeable Under TROA Table 3 Summary of 2016 Golf Course Irrigation Diversions Table 4 Summary of 2016 Water Diversions for Snowmaking in the Lake Tahoe and Truckee River Basins Table California Truckee River Depletion Table C Water Use - Public Utility Water Purveyors Lake Tahoe Basin Table C Water Use - Public Utility Water Purveyors Truckee River Basin Table C Water Use - Community Water Purveyors Lake Tahoe Basin Table C Water Use - Community Water Purveyors Truckee River Basin Table C Water Use - Non-Community Water Purveyors Lake Tahoe Basin Table C Water Use - Non-Community Water Purveyors Truckee River Basin Figures Figure 1 Lake Tahoe and Truckee River Hydrologic Basins within California Figure 2 Golf Courses in Lake Tahoe Basin Figure 3 Golf Courses in Truckee River Basin Figure 4 Snowmaking Ski Resorts in the Lake Tahoe/Truckee River Basin

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11 Introduction The purpose of this report is to comply with PL and TROA by providing an inventory of the water users and the total quantity of water used from surface and groundwater sources within the California portion of the Lake Tahoe and Truckee River basins for Calendar Year This report is prepared by the California Department of Water Resources (DWR) on an annual basis to demonstrate California s compliance with the mandated California-Nevada interstate water allocation. This report follows specified procedures for determination of the water use accounting in the Lake Tahoe Basin as required by Section 204(b) of Public Law (PL) and TROA (Section 6.D Lake Tahoe Basin Allocation Procedures), and in the Truckee River Basin as required by Section 204(c) of PL and TROA (Section 6.E California Truckee River Basin Allocation Procedures). This inventory of water use for the Lake Tahoe and Truckee River basins is to be completed and provided annually to the TROA Administrator by the end of the third quarter following the end of the subject calendar year. As a part of this report, an inventory of all known non-exempt wells constructed within the Truckee River Basin during the year of record is also included. 7

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13 Authority The California Department of Water Resources (DWR) is charged with performing the State s responsibilities related to interstate water compacts and with representing California interests in interstate water management efforts related to the Lake Tahoe, Truckee River, and Carson River basins, including the preparation of this Annual Inventory of Water Use for the Lake Tahoe and Truckee River Basins. (California Water Code Section 123) DWR will implement its responsibilities, including annual compliance requirements of PL and TROA, in coordination with the California Department of Fish and Wildlife, State Water Resources Control Board, and other agencies as appropriate. The State of California s obligation under PL and TROA correspond to several priorities as California continues to plan and manage its water resources for sustainability. The Governor s five-year California Water Action Plan, released in January 2014, describes a broad view of what is needed to meet the demands of the future. It spells out the challenges and the decisive actions required to put California on a path to more sustainable water resources: make conservation a way of life, ensure that each region within the state does all it can to put its own water resources to efficient use, protect and restore important ecosystems, and expand water storage capacity. PL and TROA directly support several priority actions contained within the California Water Action Plan, such as Action 6; to expand water storage capacity and improve groundwater management. PL and TROA also support several other actions within the plan. Action 4 is advanced under TROA, as it improves fisheries by increasing and sustaining in-stream flows and implementing habitat restoration projects. Action 5 is also advanced by allowing the use of stored water for enhanced in-stream flows and providing emergency drought storage during dry periods. 9

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15 Background The Lake Tahoe Basin is situated on the east side of the crest of the Sierra Nevada Mountains, approximately one hundred miles east of Sacramento, California. The total area of the Lake Tahoe watershed is 506 square miles, with the surface area of Lake Tahoe being approximately 191 square miles (38 percent of the total watershed area). Approximately two-thirds of the Lake Tahoe Basin lies within the State of California and the remainder is in Nevada. The Truckee River Basin includes the watershed area tributary to the Truckee River downstream of Lake Tahoe. While Lake Tahoe is fed by over 60 streams, the Truckee River located near Tahoe City, is the only outlet from the Lake. The California portion of the Lake Tahoe and Truckee River basins and their associated counties is illustrated in Figure 1. The Lake Tahoe and Truckee River regions include diverse natural resource environments that provide year-round recreation opportunities of all types. Some of the many activities available in the Lake Tahoe region are alpine and cross country snow skiing, water skiing, camping, boating, fishing, hiking, horseback riding, sightseeing, golfing, and other leisure activities. The multitude of activities in the Lake Tahoe and Truckee River areas have attracted both primary and secondary vacation home residents, visitors, and the related development and businesses to accommodate a continually increasing permanent and part-time population in the area. It is estimated the Lake Tahoe area receives over 2 million visitors a year. Population growth between 2000 and 2010 within the Lake Tahoe Truckee River basins was very modest at less than 0.5 percent, with the Tahoe Basin experiencing a slight decline in population during that decade 1. Major water purveyors located in the Lake Tahoe and Truckee River basin areas serve most of the population. In the Tahoe Basin, new development and corresponding water demands are politically and legally limited because of strict local land use controls, particularly those related directly or indirectly to sustaining the water quality in Lake Tahoe. 1 IRWM page 2-12 is the basis for this paragraph, but is not a direct quote. 11

16 Figure 1 Lake Tahoe and Truckee River Hydrologic Basins within California 12

17 The United States Congress enacted Public Law (PL) , the Truckee-Carson-Pyramid Lake Water Rights Settlement Act, in 1990 as a Congressional apportionment of Truckee River waters among all water interests. Among other conditions, this act required that a new Truckee River Operating Agreement (TROA) be implemented before the provisions for the interstate allocations of PL could take effect. TROA was conditionally approved in 2008; however, implementation was delayed pending resolution of all remaining conditions. TROA was officially implemented in December of The major signatories to TROA are the U.S Department of the Interior; the Truckee Meadows Water Authority (TMWA); the Pyramid Lake Paiute Tribe (PLPT); the State of Nevada; and the State of California. Although this inventory of water use was prepared to satisfy the reporting requirements of PL and TROA, the subject interstate water allocation has its roots in the California-Nevada Interstate Compact (Compact) which originally allocated the waters of the Truckee, Carson, and Walker rivers between the states of California and Nevada. California amended the Compact and ratified it on September 19, 1970 (Chapter 1480, CA STAT 1970). Nevada ratified the Compact again on March 5, 1971, with amendments (NRS ). The California-Nevada Compact Commission conducted negotiations on the Compact from 1955 until its ratification by both states. Congress never ratified the Compact, so it never became officially effective. The general terms though, have been observed by both states since the 1970s. The Compact set forth provisions for the equitable apportionment of waters between the two states. The annual allocation of the waters of the Lake Tahoe Basin for the State of Nevada and for the State of California is 11,000 acre-feet and 23,000 acre-feet, respectively, for use within their respective portions of the Lake Tahoe Basin. Water collected after its use, e.g., sewage effluent, is not charged against the states allocations and may be exported out of the basin. The existing diversion from Echo Lake, for use in California pursuant to rights vested under California law, is considered a transbasin diversion prior to December 31, 1959, and is not counted as part of the interstate allocation. The interstate allocation for the Truckee River Basin provides that California shall divert, or use, no more than 32,000 acre-feet per year from the upper Truckee River basin, with a maximum of 10,000 acre-feet per year coming from surface water sources. In addition, the State cannot deplete more than 17,600 acrefeet annually from the Truckee River. The annual depletion quantity refers to the amount of water which, after diversion or use, is consumed and therefore does not return to surface or groundwater sources. The annual depletion amount consists of a complex calculation which is discussed in detail within this report. Because of a senior water right and a transbasin transfer permitted prior to December 31, 1959, water decreed to the Sierra Valley Water Company is not charged to the California s interstate allocation for the Truckee Basin. 13

18 Compliance with Public Law and TROA Section 204(d)(1) of Public Law requires that compliance with the interstate allocations shall be assured by each State. To demonstrate compliance, the states of California and Nevada are each required to prepare an annual inventory of their water use, providing information necessary to demonstrate compliance with the terms and conditions of the Public Law. The required Inventory of Water Use report is provided to the TROA Administrator by the end of the third quarter (September), following the subject calendar year. PL requires that accounting for diversions shall be made based exclusively on Sections 204(b), 204(c), and the operating agreement (TROA). Selected relevant excerpts from Public Law and TROA are included in Appendix A and B, respectively, for the convenience of the reader. Water Use Inventory This report accounts for the total combined surface and groundwater use originating from the Lake Tahoe Basin. For the Truckee River Basin, the total water use in the basin is accounted for but is also separated into the specific categories of surface and groundwater use, as required. The determination of the 2016 total water use is organized and presented by its major water use categories, including (1) municipal and industrial (M&I), (2) irrigation, and (3) snowmaking. M&I use, the largest category, includes water used for commercial and industrial purposes, residential (year-round and seasonal housing), and hotels. Water used for domestic purposes and pumped from private wells is accounted for within this M&I category. Irrigation use includes golf course irrigation, construction, slope erosion control and water used for irrigation of pasture lands. Water used for snowmaking is a special type of water use recognized by Public Law and is uniquely accounted for as directed in TROA Section 6.D.6 and Section 6.E.1(e) for the Tahoe Basin and Truckee River Basin, respectively. Municipal and Industrial Use Water used for M&I purposes in the Lake Tahoe-Truckee River basins is provided by four major public water districts, approximately 20 smaller community water purveyors, over 80 non-community water purveyors, and numerous individual property owners with private groundwater wells not connected to water distribution systems. In the Lake Tahoe-Truckee River basins there are a significant population of seasonal part-time residents, including second homeowners, renters, and visitors. According to 2010 census data, seasonal, recreational, or occasional-use homes account for an average of 40 to 45 percent of all homes in the area. The proportion of seasonal or occasional use homes in individual census tracts (or portions thereof) ranges from 16 percent in Truckee to 80 percent along the southwestern shore of Lake Tahoe. 2 Private Domestic Wells Private domestic wells are categorically exempted from TROA notification requirements. Nevertheless, water use from these wells must be accounted for per PL , based on a fixed rate multiplier of 0.4 acre-feet per year if actual metered use is not available or provided. 2 Tahoe-Sierra IRWMP July 2014, pages

19 Water Purveyors Water use data for calendar year 2016 from area water purveyors was obtained by DWR from the State Water Resources Control Board (SWRCB); Division of Drinking Water (DDW). Section of the California Health and Safety Code (CHSC) defines a public water system as a system that: (1) provides water for human consumption through pipes or other constructed conveyances and has 15 or more service connections; or (2) regularly serves at least 25 individuals daily at least 60 days out of the year. Section of the CHSC requires that public water systems submit a technical report, including the total amount diverted, to the DDW when requested. These technical reports are currently required to be submitted annually for every public water system under DDW jurisdiction. Additionally, they must specify official contacts and operational information for the calendar year reported. These annual reports must be submitted to SWRCB no later than April of the following year. This information is then provided to DWR staff for use in informing and populating several reports, including this water usage inventory. The provided information identifies the water purveyors, the number of connections, the number of persons served, and the amount of water diverted/used that year. For purposes of this water inventory water purveyors are classified into one of three major representative groups defined below: Public Utility Districts (PUD) Within the Lake Tahoe-Truckee River basins in California, there are four public utility districts (PUD) operating public water systems. The Lake Tahoe Basin public utility districts include: (1) North Tahoe Public Utility District, (2) South Tahoe Public Utility District, and (3) Tahoe City Public Utility District. The primary public water utility in the Truckee River Basin is the Truckee-Donner Public Utility District (TDPUD). The Tahoe City PUD also has a small portion of their service area in the Truckee River Basin located east of Squaw Valley on Highway 89. In addition to reporting their operations and water usage annually to the DDW, these PUDs are required by the Urban Water Management Planning Act of the California Water Code to develop an urban water management plan every five years. This plan must include an assessment of water supply reliability over a 20-year horizon and development of water conservation programs to meet statewide goals to reduce water consumption by 20 percent per capita by Community Water Purveyors Community water purveyors in the Lake Tahoe-Truckee River basins are defined as public water systems serving at least 15 service connections used by year-long residents or regularly serving at least 25 yearlong residents of the area. Annual water use data for community water purveyors was generally obtained from DDW reports provided to DWR. Community water purveyors include public utility districts. In this report, the PUDs are reported as a separate category because of the additional reporting required by their large customer base. Non-Community Water Purveyors Non-community water purveyors are public water systems that are not a part of a community water system. If available, non-community water purveyors water use data was obtained from DDW reports. When the information was not provided by the owner or available from DDW, the water use from 15

20 identified non-community water purveyors was estimated by DWR based on the same method as for commercial properties not connected to a domestic water distribution system. The method for estimating this information included DWR personnel performing field inspections, contacting local non-community water purveyors, and making estimates based on industry-recognized water use standards for typical noncommunity commercial activities such as motels, resorts, apartment buildings, campgrounds, and multi residential associations. Conservative assumptions were made when no other information was reported or available to reflect water usage. Although conservative assumptions were generally made, this is recognized as an inconsistent and imperfect method that will certainly be improved in future years with further outreach, education, and better reporting participation. Table 2 summarizes the total water use for Public Utility Districts and community and non-community water purveyors for the Lake Tahoe and Truckee River basins. Table 2 also includes the reportable water use for properties not connected to a distribution system. Appendix C includes a complete listing of the public utilities, community and non-community water purveyors currently known to DWR, and their associated water use for 2016, reported or estimated. Properties Not Connected to a Metered Domestic Water Distribution System TROA Sections 6.D and 6.E require California to report the number and types of unmeasured/unmetered water uses in the Truckee River Basin to the TROA Administrator. Sections 204(b)(2)(B) and 204(c)(1)(J) of PL require that unmeasured water use for residential domestic purposes in the Lake Tahoe and Truckee River basins be charged at the annual rate of 0.4 acre-feet against California s respective annual allocations. TROA Sections 6.D.4 and Section 6.E.1(c) require unmeasured nonresidential uses to be charged to the expected water use specified in the State permit or license to divert the water. If such a permit or license does not exist or if an expected water use is not specified in the State permit or license, unmeasured water used for non-residential purposes shall be determined from appropriate procedures jointly developed by California and Nevada. Current inventories of the number and types of unmeasured water sources are based on well information from past well data provided by local permitting agencies. For many years, DWR has maintained a database of California Well Completion Reports as part of the State s Groundwater Supply Assessment Program. These Well Completion Reports are generally prepared by the well driller and submitted to the local permitting agency whenever a driller proposes to construct, alter, or destroy a well, and then provided to DWR. The database generally includes well number, DWR log number, address or general well location information, start and completion dates, permit type, and water supply type. Water supply types identified as domestic supply that are not already accounted for under water purveyors and irrigation are those wells associated with unmeasured water use. Domestic supply wells reported to DWR, which are not already identified and accounted for under the water purveyors and irrigation sections, were field checked, where possible, to determine if they appeared to serve a single residence, multi-residences or other commercial use. The number of single household residences, not connected to another water distribution system, based on the reported domestic groundwater wells in the current DWR database is 93 residences in the Tahoe Basin and 539 residences in the Truckee River Basin. In order to quantify water use for these unmetered single users, the number of residences with water provided solely by unmetered or unreported domestic wells is multiplied by the rate of 0.4 acre-feet per residence. 16

21 Unmeasured commercial use connections, based on existing well database investigations performed by DWR, and verified when necessary by field inspections, were identified based on their occupancy and type of commercial use. For those motels that are on well water, their diversions were estimated from the number of units, assumed occupancy, and per capita usage rates. The usage rate was assumed to be 253 gallons/person per day, which is the average baseline use determined by DWR for the North Lahontan Hydrologic Region. Since residents in the Lake Tahoe-Truckee area generally do not use as much water for landscaping as the residents of drier portions of the hydrologic region, such as those lying in Modoc, Lassen, or Mono counties, the calculated number, using this assumed value, is conservative, which is to say it most likely overestimates the actual water use. In future years, better reporting, and further examination and understanding of the water use rates will likely yield estimates that are lower and closer to reflecting the actual water usage amounts. In the case of motels, the assumed daily use figure is also determined by assumed occupancy rates. In estimating the unmetered uses at parks and picnic areas, the daily use amounts were assumed to be less than for motels, and were taken from Title 23 California Code of Regulations, Section 697, which specifies the amount of water reasonably necessary for such transient use facilities. Table M&I Water Diversions Chargeable Under TROA Truckee River Basin (acre-feet) Municipal & Industrial Lake Tahoe Basin (acre-feet) Surface Water Groundwater Public Utility Districts 7, ,996 Community Purveyors 2, ,130 Non-Community Purveyors 1, Properties Not Connected to a Distribution System (including private domestic wells) Subtotal 11, ,860 Total Water Use 11,450 acre-feet 6,090 acre-feet (Combined) (230 acre-feet total use reported from surface water sources) 17

22 Water Use for Golf Course Irrigation The Lake Tahoe Basin is home to five golf courses, including Bijou Municipal, Lake Tahoe, Old Brockway, Tahoe City, and Tahoe Paradise. Refer to Figure 2 for an exhibit illustrating the general location of these golf courses. The Truckee River Basin offers ten golf courses, including Coyote Moon, Gray s Crossing, Northstar-at-Tahoe, Old Greenwood, Ponderosa (a smaller 9-hole course), The Resort at Squaw Valley, Schaffer s Mill, Martis Camp, Lahontan, and Tahoe Donner Golf Course. Refer to Figure 3 for an exhibit showing the locations of these golf courses. Metered water use for golf course irrigation during calendar year 2016 was documented and provided to DWR by most of the courses or by the water agency providing for its water. Metered golf course water usage demonstrated an approximate average irrigation rate of approximately 2.2 acre-feet per acre for For golf courses that do not yet meter their use, this average application rate was utilized and prorated over the reported irrigated acreages of the unmetered golf courses for purposes to establish approximate water use quantity for this report. Efforts will be made in future years to obtain more accurate information that is specific to each golf course. Irrigated acreage calculations were obtained from the individual golf courses and generally confirmed by DWR using Geographic Information System (GIS) methods. For calendar year 2016, golf course irrigation in the Lake Tahoe basin accounted for 500 acre-feet of water use. Water use for Golf course irrigation in the Truckee River basin for the same period accounted for 1,920 acre-feet. See Table 3 for a summary of the irrigated acreage and the annual water use for the golf courses in the Lake Tahoe and Truckee River basins. 18

23 Figure 2 Golf Courses in Lake Tahoe Basin 19

24 Additional Water Use for Irrigation in Lake Tahoe and Truckee River Basins TROA Section 6.E.1(d) requires California to report the annual irrigated acreage in the Truckee River Basin. With the exception of golf courses and to an extremely minor degree, water used for irrigation of erosion protection or construction and dust control, etc., there is assumed negligible additional reportable irrigated acreage within the Truckee River Basin. More research and outreach will be conducted in future years to establish a database and a reportable record of water use for this category. Figure 3 Golf Courses in Truckee River Basin 20

25 Table 3 Summary of 2016 Golf Course Irrigation Diversions Lake Tahoe Basin Golf Course Irrigated Acreage (acres) Water Usage (acre-feet) Application Rate Factor (ac-ft / ac) Notes Old Brockway * Served by North Tahoe PUD, per David Laurie, 8/8/17; Per Meeting Water Right by Deed of 1465 acft/yr. No metering. *Assumed 2.2 average rate factor Tahoe City Per Tony Laliotis, TCPUD via 8/11/17 . Bijou Municipal * Acreage provided by Jason Burke, via 7/24/17 (served by private well in wet area, low usage area. *Rate factor of 2.0 assumed) Lake Tahoe Per Bobby Jaeger. 7/19/17 Tahoe Paradise * They do not meter their use from their 2 wells, per Colby Gunsch 8/10/17. *Usage estimated based on 2.2 average rate factor Total Water Used Truckee River Basin Golf Course Irrigated Acreage (acres) Gray's Crossing 118 Old Greenwood 141 Ponderosa (9-hole course) Water Usage (acre-feet) Application Rate Factor (ac-ft / ac) Coyote Moon Schaffer's Mill Notes Served by TDPUD wells per Brian Wright 8/7/17 Per Mike, TDP&R Dist. (8/7/17) Confirmed low rate is likely correct due to pump & system problems experienced this year, use is from surface water Served by TDPUD wells per Brian Wright 8/7/17 Provided by Joshua Detweiler & Rob Williams via 8/11/17 21

26 Truckee River Basin (Cont d) Golf Course Irrigated Acreage (acres) Water Usage (acre-feet) Application Rate Factor (ac-ft / ac) Notes Lahontan Per Mike Cornette, 8/8/17 Northstar Martis Camp Tahoe - Donner * Squaw Creek Per David Bailey, Total ac-ft used acft provided from NCSD, 48 af of af use is Surface Water Includes golf, soccer, parks, associated. Landscape. Per Scott Bower 7/19/17 Per Brian Wright, 61 ac-ft was provided by TDPUD to supplement irrigation from on-site private well. *Since no information was provided on private well, an assumed 2.2 rate factor was used. Per Andre Preimer, 7/25/17 Total Water Used 967 1,920 Surface: Groundwater: 80 acre-feet 1,840 acre-feet 22

27 Water Used for Snowmaking Snowmaking is another reportable use of water in the Lake Tahoe and Truckee River basin areas. PL and TROA have special provisions for charging the water used for snowmaking against California s water allocation. For snowmaking within the Lake Tahoe Basin, TROA provides that the first 600 acre-feet used is exempt and allowed without any charge against the state s allocation. After the first 600 acre-feet, 16 percent of the additional water used for snowmaking is charged against the state s allocation. Heavenly ski resort was contacted and provided the amount of water used for their snowmaking in California. The 2016 water use for Homewood snowmaking was based on information received from Tahoe City Public Utilities and Madden Creek Water Company. Table 4 summarizes the reported water used for snowmaking in the Lake Tahoe Basin during calendar year As illustrated in the table, a total of 150 acre-feet was diverted in Therefore, the amount chargeable to California s allocation is zero since that amount falls within the 600 acre-feet exemption for the Lake Tahoe basin. Similarly, for snowmaking in the Truckee River Basin, the first 225 acre-feet used for snow making is exempted by TROA, and 16 percent of the remaining water use is then charged against the state s allocation. The 2016 water use for snow making was provided by Squaw Valley, NorthStar, and Alpine Meadows ski resorts. Tahoe Donner Downhill Ski Resort began snowmaking operations in 2016 and its related water use was not reported separately for purposes of this assessment. Nonetheless, all of the water used for snowmaking operations at Tahoe Donner was provided by Truckee Donner PUD and is accounted for within TDPUD s reported water deliveries. Consequently, the reportable water use is conservatively stated because the snowmaking water was not adjusted for its net consumed value, as provided for in TROA. The total water use reported for snowmaking in the Truckee River Basin during 2016 was 760 acre-feet and therefore the reportable charge against the California Truckee River basin allocation is 85 acre-feet. Figure 4 shows the locations of the ski resorts within the Lake Tahoe and Truckee River basins that reported regularly utilizing snowmaking in their business. 23

28 Figure 4 Snowmaking Ski Resorts in the Lake Tahoe/Truckee River Basin 24

29 Table 4 Summary of 2016 Water Use for Snowmaking in the Lake Tahoe and Truckee River Basins Manner of Use Lake Tahoe Basin (gallons)) Truckee River Basin (gallons) Alpine Meadows 50,327,930 Northstar 156,947,318 Squaw Valley 39,047,564 Tahoe Donner Not Reported (See Note below) Homewood 6,699,100 Heavenly 40,177,000 Total Reported Water Use for Snowmaking in 2016 (gallons) Total Reported Water Use for Snowmaking in 2016 (acre-feet) 46,876,100 gallons 246,322,812 gallons 150 acre-feet (rounded) 760 acre-feet (rounded) Amount Exempted Per PL Net Diversion Amount Charged to Annual Allocation (16% of Net Diversion) 0 85 Note: Tahoe Donner Downhill Ski Resort began snowmaking operations in 2016 and its related water use was not reported separately for purposes of this assessment. All water used for snowmaking operations at Tahoe Donner was provided by Truckee Donner PUD and is accounted for within TDPUD s reported water deliveries. 25

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31 Truckee River Total Depletion Calculation For the Truckee River Basin, TROA requires that California diversions pursuant to the interstate allocation shall result in no more than 17,600 acre-feet of water, from surface and groundwater sources, being depleted from the watershed in any given year. The procedure provided in TROA Section 6.E.2 is the exclusive means of determining compliance with this limitation. The Truckee River Total Depletion Equation applies only to the Truckee River Basin in California and is calculated using components of water use under various major categories and multiplying each of these components by a factor to determine the total annual depletion. Though not all categories or components will apply in a given year, the major categories of water use that may be considered in determining the annual depletion include: Domestic / Residential Water Use Reservoir Evaporation (of California's stored water) Groundwater Recharge Snowmaking Water Use Irrigation Water Use Commercial / Industrial Water Use Miscellaneous Water Use The Truckee River Total Depletion Equation is a complex combination of forty-two individual factors which results in the final total estimate for the amount of water that is consumed and depleted from the Truckee River basin during the calendar year. The equation requires the differentiation or disaggregation from gross water amounts required by the interstate allocation of those uses that were, for instance, connected to the Truckee Tahoe Sanitation Agency (TTSA) waste water treatment facility (Type M 1 ) from those that were served by individual waste disposal systems (Type M 2 ). This differentiation was accomplished by using web/internet operable GIS information systems and web/internet accessible assessor s office records and assessor parcel maps for the three counties located within the California Truckee River Basin area. This information, used in combination with available maps of water and sewer lines provided by TTSA, the Truckee Sanitation District, and other agencies were then used in a parcelby-parcel examination to determine the service type for each property. This analysis is further complicated by the fact that, though most of the Truckee area is within the TTSA service area, over 2,000 residences located within the service area are believed to not be currently connected to TTSA facilities. Based on the calculation methods defined in TROA and any necessary assumptions utilized in the calculation, the California Truckee River Total Depletion for 2016 is 2810 acre-feet, 16 % of the 17,600 acre-feet maximum amount permitted annually by TROA. The total annual depletion is calculated pursuant to the California Truckee River Total Depletion Equation described in Section 6 of TROA Appendix 6.B, with definitions of the equation parameters provided in TROA Appendix 6.C and the initial depletion equation constant factors provided in TROA Appendix 6.D. The initial depletion equation constants will be used, without change, for the first 10 years of TROA implementation per Section 6.E.2(c). Because of the complexity of the equation and the many factors and detailed analysis of actual basin water use, certain assumptions were necessary. Assumptions used are generally intended to reflect conservative results. Over time and in future water use inventories, 27

32 these assumptions are anticipated to be replaced with more accurate data, supported by further studies and improved reporting methods. The methods of calculation, initial constants used and assumptions utilized in determining the total Truckee River Annual Depletion for 2016 by major categories and its components is summarized below. Additional details and definitions of the constants and variables are described in TROA, Appendix 6.B, 6.C and 6.D. 1. Domestic / Residential Water Use a. Depletion component from residential outdoor use, connected to Tahoe- Truckee Sanitation Agency (TTSA) Depleted Amount = D M1A * C M1A * T * M 1 (percent depleted (D M1A )) x (percent used outdoors (C M1A )) x (Total Water used by residents connected to TTSA (T*M 1 )) The following initial depletion equation constants are specified and defined in TROA, Appendix 6.D: D M1A = 0.85 C M1A = 0.4 T = 0.9 M 1 = 2,629 acre-feet M 1 refers to the portion of M&I water (Table 2) delivered to residences connected to TTSA. The depleted amount for residential outdoor use, connected to TTSA = 804 acre-feet b. Depletion component from residential outdoor use, not connected to TTSA Depleted Amount = D M2A * C M2A * T * M 2 (percent depleted (D M2A )) x (percent used outdoors (C M2A )) x (Total Water used by residents not connected to TTSA (T*M 2 )) The following constants are specified and defined in TROA, Appendix 6.D: D M2A = 0.85 C M2A = 0.4 T = 0.9 M 2 = 197 acre-feet 28

33 M 2 refers to the portion of M&I water (Table 2) delivered to residences not connected to TTSA. Depletion from residential outdoor use, not connected to TTSA = 60 acre-feet c. Depletion component from residential indoor use, not connected to TTSA Depleted Amount = D M2B * C M2B * T * M 2 (percent depleted (D M2B )) x (percent used indoors (C M2B )) x (Total Water used by residents not connected to TTSA (T*M 2 )) The following initial constants are specified and defined in TROA, Appendix 6.D: D M2B = 0.15 C M2B = 0.6 T = 0.9 M 2 = 197 acre-feet M 2 refers to the portion of M&I water (Table 2) delivered to residences not connected to TTSA. The depleted amount from residential indoor use, not connected to TTSA = 16 acre-feet d. Depletion component from multi-residential outdoor use, not connected to TTSA Depleted Amount = D M3A * C M3A * T * M 3 (percent depleted (D M3A )) x (percent used outdoors (C M3A )) x (Total Water used by multiresidences not connected to TTSA (T*M 3 )) The following constants are specified and defined in TROA, Section 6.D: D M2A = 0.85 C M2A = 0.4 T = 0.9 M 3 = 25 acre-feet M 3 refers to the portion of M&I water (Table 2) delivered to multi-residential not connected to TTSA. The depleted amount from multi-residential outdoor use, not connected to TTSA = 8 acre-feet 29

34 e. Depletion component from multi-residential indoor use, not connected to TTSA Depleted Amount = D M3B * C M3B * T * M 3 (percent depleted (D M3B )) x (percent used indoors (C M3B )) x (Total Water used by multiresidences not connected to TTSA (T*M 3 )) The following constants are specified and defined in TROA, Appendix 6.D: D M3B = 0.15 C M3B = 0.6 T = 0.9 M 3 = 25 acre-feet M 3 refers to the portion of M&I water (Table 2) delivered to multi-residential not connected to TTSA. The depleted amount of indoor use for multi-family residences not connected to TTSA = 2acrefeet 2. Reservoir Evaporation (of California's stored water) a. Depletion component from evaporation from water diverted to Truckee River Reservoirs, Donner Lake, and Independence Lake storage which is charged to California allocation. Depleted Amount = E 1 = 0 In 2016, there were no California water rights diverted to storage into reservoirs which were charged to the California allocation. b. Depletion component from evaporation from water diverted to storage other than Truckee River Reservoirs, Donner Lake, and Independence Lake which is charged to California allocation. Depleted Amount = E 2SA * E 2PE * E 2PC = 0 In 2016, there was no water diverted to storage into reservoirs which was charged to the California allocation. 3. Groundwater Recharge a. Depletion component from evaporation of water diverted to percolation 30

35 ponds for groundwater recharge which is charged to California allocation. Depleted Amount = E 3SA * E 3PE * E 3PC = 0 acre-feet In 2016, there was no known or reported water diverted to percolation ponds for groundwater recharge which was charged to the California allocation. 4. Snowmaking Water Use a. Depletion component from evaporation and sublimation of water diverted for snowmaking. Depleted Amount = D S * S (percent depleted (D S )) x (Total Water used for snow making (S)) The following constants are specified and defined in TROA, Appendix 6.D: D S = 0.16 S= 760 acre-feet (See Table 4) S represents the amount of water diverted for snowmaking in the Truckee River Basin. This figure was provided by Table 4, Total Reported Amount of water used for Snowmaking in The depleted amount of water used to make snow = 122 acre-feet 5. Irrigation Water Use a. Depletion component from water used for Agriculture Irrigation Depleted Amount = D I1 * I 1 = 0 acre-feet In 2016, there was no reported water diverted to irrigate agriculture in the California s portion of the Truckee River Basin. b. Depletion component from water used for Erosion Control Depleted Amount = D I2 * I 2 (percent depleted (D I2 )) x (Total Water used for erosion control (I 2 )) The following constants are specified and defined in TROA, Appendix 6.D: 31

36 D I2 = 0.8 I 2 = 1 acre-feet (calculated quantity) I 2 represents the actual amount of water diverted for erosion control. The depleted amount of water used for erosion control = 0 acre-feet c. Depletion component from water used for Irrigation of golf courses and median strips Depleted Amount = D I3 * I 3 (percent depleted (D I3 )) x (Total Water used for to irrigate non-agricultural land, including golf courses, parks and green-belts (I 3 )) The following constants are specified and defined in TROA, Appendix 6.D: D I3 = 0.8 I 3 = 1,913 acre-feet I 3 represents the actual amount of water (Table 3) diverted to irrigate non-agricultural land, including golf courses, parks and green-belts. The depleted amount of water used irrigation of greenbelts / golf courses =1,530 acre-feet 6. Commercial / Industrial Water Use a. Depletion component from water used for commercial/industrial landscaping Depleted Amount = D B1A * C B1A * T * B 1 (percent depleted (D B1A )) x (percent applied for landscaping (C B1A )) x (Total Water used for business, commercial, or industrial facilities (T*B 1 )) The following constants are specified and defined in TROA, Appendix 6.D: D B1A = 0.8 C B1A = 0.1 T = 0.9 B 1 = 1,482 acre-feet 32

37 B 1 refers to the portion of M&I water (Table 2) delivered to business, commercial, or industrial facilities. The depleted amount of water used in landscaping by commercial Enterprises = 107 acre-feet b. Depletion component from water used in industrial process by commercial/industrial facilities Depleted Amount = D B1B * C B1B * T * B 1 (percent depleted (D B1B )) x (percent incorporated into the industrial process (C B1B )) x (Total Water used for business, commercial, or industrial facilities (T*B 1 )) The following constants are specified and defined in TROA, Section 6.D: D B1B = 0.1 C B1B = 0.9 T=0.9 B 1 = 1482 acre-feet B 1 refers to the portion of M&I water (Table 2) delivered to business, commercial, or industrial facilities. The depleted amount of water used in industrial process by commercial/industrial = 120 acrefeet c. Depletion component from indoor water used by commercial/industrial facilities, not connected to TTSA Depleted Amount = D B2 * C B2 * T * B 2 (percent depleted (D B2 )) x (percent used indoors (C B2 )) x (Total Water used for business, commercial, or industrial facilities which are not connected to TTSA (T*B 2 )) The following constants are specified and defined in TROA, Section 6.D: D B2 = 0.15 C B2 = 0.6 T = 0.9 B 2 = 445 acre-feet (calculated quantity) B 2 refers to the portion of M&I water (Table 2) delivered to business, commercial, or industrial facilities which are not connected to TTSA. 33