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HomeMy WebLinkAbout04/07/1992, 5 - THE 1992 - 1993 WATER OPERATIONAL PLAN IIINIIINII"IIIII�pI`��IUI`I "J T MEETING GATE: CiQ San IS QBISpQ Aril 7, 1992 COUNCIL AGENDA REPORT ITEM NUMBER: FROM: William T. Hetland Prepared By:Gary Henderson, Water Division Manager Utilities Director Ron Munds, Water Conservation Coordinator Sue Baasch, Administrative Analyst SUBJECT: The 1992 - 1993 Water Operational Plan CAO RECOMMENDATION: By motion, 1. Receive and file report, providing direction to staff, as necessary; and 2. Approve reduction of City's Safe Annual Yield from 7,860 acre feet per year to 7,735 acre feet per year, which includes coordinated reservoir operations and 500 acre feet per year of groundwater. REPORT IN BRIEF: The City of San Luis Obispo experienced a near normal rainfall year this past year, which resulted in a significant increase in storage at Salinas Reservoir, currently at approximately 96% of capacity. Whale Rock Reservoir has not responded as quickly and is currently at approximately 44% of capacity. The increase in storage, a 78% increase in total storage from the end of January to the end of February, allowed the City to exit mandatory conservation on March 3, 1992. The City had been in varying levels of mandatory conservation since April, 1989, a period of 36 months. Although the drought situation has eased, another year of continuing drought conditions may require a return to Stage 1, 15% mandatory conservation, in the spring of 1993. The City's Reservoir Storage Curve is updated monthly with current storage information. Figure 6 shows the storage curve updated with February storage information and revised assumptions related to groundwater and action levels for conservation. The model uses very conservative rainfall and inflow estimates based on 1989 information. Using these worst case assumptions of the continuation of drought conditions, the model predicts the City's water supply could reach minimum pool in late spring of 1996. Staff revised the City's Safe Annual Yield computer model. The prior adopted safe annual yield figure of 7,860 acre feet per year (afy) was based on a six year dry cycle which occurred in 1946-51. The revised safe annual yield of 7,735 afy is now based on the 1986- 91 drought which is worse than the previous 1946-51 period. FISCAL IMPACT: The identified programs, if not currently reflected in the 1991/93 Financial Plan, will be presented individually for Council consideration. No additional appropriation is required to support these activities at this time. CONCURRENCES: The Community Development Department has reviewed and approved this plan. Attachment: 1992-1993 WATER OPERATIONAL PLAN 5- l�ll��►�N►�Illlllllll1° IIUIN city of San Luis osIspo COUNCIL AGENDA REPORT City of San Luis Obispo 1992-1993 WATER OPERATIONAL PLAN I. INTRODUCTION The first Water Operational Plan Policy Statement was adopted in 1985 as a means of monitoring the City's water supply and reviewing current programs to address possible diminishing supplies. This 1992 - 1993 annual report reviews current and projected reservoir storage situations both from the viewpoint of continuation of the drought and.from strategic programming to promote long-term water use efficiency. While the spring rans and runoff brought temporary relief to the water situation, it is important to remember that the drought may continue and, even if rainfall returns to pre-drought levels, indoor and outdoor water use efficiency will continue to be a high priority for the City. 11. EXISTING WATER SUPPLY STATUS As of March 1, the Salinas Reservoir was ANNUALRESERVOIR RAINFALL 93.3% full at 22,244.5 1980 - 1992 AF capacity. As of March 1, the City's proportionate share of Whale Rock storage was 7,962.61 AF, or 36%. The combined total of 30,207.11 AF, is 65% of Z the maximum City storage. This is a little o over four years of water w z supply. ^- ,.. .� •-� .,.�..- Z February rainfall was mmn I 1038 inches at Salinas Reservoir and 7.09 _ ._ • r inches at Whale Rock. Calendar Year Totals Total seasonal amounts are 19.66 inches and Salinas Dam = Whale Rock 15.44 inches respectively. This years rainfall has Figure 1 Reservoir Rainfall 1980 to 1992 significantly improved the storage at the reservoirs. Reservoir storage is augmented by groundwater. At this time, approximately half of the water used within the City each month comes from wells. It is expected that this level of production may decline as the groundwater basin is lowered. As is shown in Figure 2, groundwater production has averaged about 1,950 feet in each of the year's of full production. 5- 1111�11maiilljP101, �l city of San �,6 OBISpo COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 2 GROUNDWATER PRODUCTION 1989 - 1992 Ina mTAL TTD-201 LF - y� TOT�I.1,880 ii tliBt� ' r �' rtoTu•1,i6i 4F 'AD. m m L6 - -view RWAI-An AF Iwo tavl - levi bu hL No Apr WF Juuu .luh Aug 220 Oet Ma. Os Figure 2 Groundwater Production 1989 to Present Water Consumption and Conservation The City of San Luis Obispo has been outstanding in its efforts to cut water consumption. Figure 3 on the next page illustrates the level of conservation in the community since the program began. in 1988. Using consumption levels from 1987 as the base for comparison, staff estimates that approximately 11,000 acre feet have been saved due to the community's excellent conservation efforts. The increase in storage due to February rains and inflow allowed the community to leave mandatory conservation on March 3, 1992. Historically, during mandatory conservation the community exceeded the mandated level by at least 10%. Following the relaxing of 35% mandatory conservation last April to 15% mandatory conservation, the community continued to conserve at 26 to 54% below 1987 levels. Figure 4 shows what our history has been over the last year regarding water conservation. Staff feels there are at least two reasons for the high level of conservation. Consumers are still taking a very cautious approach to increasing water use and realize the drought is not over. Secondly, it appears that conservative water use habits have been adopted by most of the community. The retrofitting of toilets, shower beads, and more efficient irrigation systems have increased water efficiency and will continue to conserve water, even after the drought is over. The City is currently using about 400 acre feet per month (Figure 4). What will be the level of consumption now that the community has left mandatory conservation? That is the question that all water agencies who have recently left mandatory conservation are asking. Some level of permanent conservation is expected, but a return to pre-drought levels of consumption are expected to occur, probably over a period of years. ����u�►�u��IIIIIII�I�`����`� city of San A OBISpo COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 3 Water Conservation Report Card 87-92 Use Compared to 1987 Base PROGRAM BEGAN IN FY 88/89 so N. 8000 11 A APPA4 11,000 AFSAVO 3n3' WDA 700 SINCL?.ROG;,UM B,IRAN , 36%6000-11 A 39% r UM11 4000-1.1 46% m 3000-11 on a �R. 88/89 89/90 90!91 01192 AVERAGE PerCent Conserved (Compared to 87 Base) Actual Water Use Base Year Water Use Fipre 3 1987/92 Water Conservation Program CITY OF SAN LUIS OBISPO 1991/92 Water Use 1991 Jan 333.63 AF Feb 316.83 AF Mar 307.69 AF Apr 348.56 AF May 434.78 AF Jun 411.36 AF Jul 427.66 AF Aug 463.25 AF Sept 436.31 AF Oct 434.14 AF Nov 372.58 AF Dec 349.23 AF 1992 Jan 348.22 AF Feb 314.92 AF Figura 4 San Luis Obispo 1991/92 Water Use 5-4 111161(1IIIII(11101 city Of san L_ AS OBIspO COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 4 111. MULTI-SOURCE WATER SUPPLY PROJECTS In November, 1990, the Council adopted a multi-source water supply policy. This policy stated that the City would not rely on a single source of water to meet its permanent water needs. At that time, staff also identified a supplemental water requirement of 6,540 AF to serve the full build-out capacity of the City as represented in the General Plan and create a water supply contingency. To this end, numerous short and long-term water supply projects are under development at this time. The following is a status report on each of these projects: Salinas Reservoir Expansion The initial feasibility study including seismic analysis and initial environmental review have been completed. This work showed that the project was technically feasible, cost effective i and environmentally sound. Staff has met with the staff of north county communities to discuss the project and review concerns those communities may have. Formal public presentations to the various north county councils and boards have been completed. Council recently authorized the contract with Woodward/Clyde Consultants for the preparation of the environmental impact report (EIR). The draft EIR is scheduled to be completed by December 1992, with Council certification of the final EIR in March 1993. The design and permitting phase is estimated to require a year to complete. Construction is estimated to begin in the summer of 1994 with completion of the project in the summer of 1995. State Water Project Much activity occurred in the State Water Project this past year. An advisory election was held in San Luis Obispo in April, 1991, and the vote was of 52% (4,198 votes) to 4717o (3,716 votes) in opposition to the project. Elections in Santa Barbara County resulted in a number of communities choosing to join the State Water Project. This will result in the State Water Project proceeding with design and construction. The Final Environmental Impact Report for the Local Projects was recently completed. The County has stated that San Luis Obispo City Council must make a formal determination on participation in the State Water Project by May 1, 1992. Nacimiento Diversion Project The City of San Luis Obispo investigated the possibility of developing a Nacimiento water supply project. This project became more attractive after the April advisory election on the State Water Project indicated a citizen preference that the project not be approved. The Nacimiento project is technically feasible for the City to pursue alone, but the City realized the significant regional concerns and requested that San Luis Obispo County be the lead agency and begin development of a regional project. The County is currently in the process of initiating a contract with Boyle Engineering Corporation to provide a feasibility study of the project The contract is divided into three phases. The first phase will be a reliability assessment of the safe annual yield of the reservoir which is expected to be done in May of 1992. The second phase will address agency allotments, alternative project designs, and geotechnical studies. The second phase is 5-S mH�►b�i�illllll�P° li�ll city of San Luis OBISPO COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 5 scheduled to be completed .eight months after the notice to proceed is issued by the County. Phase three will involve the preparation of a final report which is to be completed within 10 weeks of the notice to proceed is issued for this phase. The above timeframes will result in completion of all phase in the spring of 1993. Groundwater Wells i The current groundwater program utilizes seven municipal wells and two or more irrigation wells. At this time, wells are producing approximately 160 acre-feet (af) per month which represents about 45% of the total City water demand. Prior to this years rains, the wells showed declines in pumping water elevation. After the February rains, the groundwater levels rose to the levels that were encountered at the start of the City's Groundwater Development Program in 1989. The City will continue to use well water as a key element of our water resources. Wastewater Reclamation Reclaimed or recycled water is intended to be a long-term water source for the City. The current quality of the effluent from the City's Wastewater Treatment Plant (WWTP) meets secondary treatment standards. The $35 million WWTP upgrade that is underway will improve the effluent quality to an advanced level, so that a full water reclamation program can be implemented. At this advanced level of treatment, the reclaimed water can be used for park and playground irrigation, landscape or recreational impoundments, industrial applications, construction use and other beneficial non-potable uses. i By using treated wastewater effluent for non-potable water demand such as landscape irrigation, the City's potable water will be made available for uses that require a higher quality of water. Staff has estimated that reclaimed water could offset 800 to 1200 acre feet per year of existing potable water demand by existing non-potable uses. The water reclamation program is in the conceptual phase of its development. In this phase market research is being performed, regulations are being researched and a feasibility study is being performed. This phase of the water reclamation program is due to be completed by mid-1992- Before reclaimed water can be delivered to customers, the following must be accomplished: prepare and certify the environmental documents; prepare an engineering report and its submittal to the Department of Health Services (DHS) and the Regional Water Quality Control Board; establish user contracts; establish revenue program; perform a detailed design of storage, pumping and distribution facilities; and construction of those facilities. Staff has estimated that reclaimed water to meet the DHS requirements for unrestricted public contact will be delivered to the first customers in late 1994. Cloud Seeding In January, 1991, the City Council approved an agreement with Atmospherics Incorporated of Fresno, California to provide a three-year cloud seeding program. The program "target areas" are the Salinas reservoir and Lopez Lake watersheds. The County of San Luis Obispo participated in the project and agreed to pay 37.8% of the total costs. During this years operational period which started November 1, 1991, seventeen airborne seeding flights 5 iiii�l►1�►►IIiIIIIIIIIII�� ��III city of San Luis OBISpo RENEW COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 6 were conducted. . Seeding conditions were rated from poor to excellent. Aircraft operations logged a total of 63.7 hours, dispensing a total of 3,580 grams of silver iodide. Opportunities for cloud seeding in February exceeded the average HISTORY OF WATER CONSERVATION PROGRAM expectations. A total of 6 storm periods moved through the San Luis The Mandatory Water Conservation Program has been Obispo area during the month. extremely successful in achieving the City's goal of Within theses storm periods 8 flights reducing water consumption. Overall consumption has were launched. Seeding occurred on averaged 43% to 46% of 1987 consumption levels for the 7 of these, with the other flight last 24 months. classified as storm reconnaissance with no subsequent identifiable 25% Mandatory Program - April, 1989 seeding opportunities. Silver iodide Mandatory water conservation was first implemented in ground generators were active during 1989 at the level 25% reduction from 1987 base year one of the storm periods as a consumption. At that time, average consumption per supplement to the airborne seeding single family household was 25 units per billing period. program. On three occasions, the The ceding was set at 40 units. program was temporarily suspended for 24 hours in keeping with - 35% Mandatory Program - July, 1990 suspension criteria focused on public Mandatory conservation at the 35% level was approved to safety considerations. be implemented in July, 1990. The program included enforcement of certain water waste actions and a system IV. WATER CONSERVATION of surcharges for excessive water use. The ceiling was set at 25 units. Increasingly, throughout the State, the expression "water conservation" is 15% Mandatory Pr r m - April, 1991 being replaced with the term "water The 35% mandatory program was relaxed to a 15% efficiency". As the City moves mandatory program following the March, 1991, rains. further into the 1990's, water City Council adopted the program on April 15, 1991, efficiency will become a key factor in keeping in place surcharges and the Water Waste insuring the water future for our Municipal Codes. The ceiling was set at 35 units. community. Council approved two activities Figwe S HISTORY OF MANDATORY WATER recently to promote water efficiency- CONSERVATION -adoption of "Best Management Practices" and development of a comprehensive water hardware retrofit program. At the September 3, 1991 City Council meeting, Coucnil adopted the "Best Management Practices" which are sixteen water conservation measures to promote water efficiency. At the February 4, 1992 City Council meeting, Coucnil directed staff to develop a comprehensive water hardware retrofit program and indicated that an ordinance requi=* g retrofit upon sale, remodel or change in use should be presented for consideration. In the near future, staff will be presenting this ordinance to Council. ii�Pu11�IIII�IIIIIII���� l�„I cut/ of San Luis OBIspo COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 7 V. PROJECTED WATER SUPPLY SITUATION Reservoir Storage Curve The Reservoir Storage Curve is integral to the City's Annual Water Plan analysis. It is a model to estimate the City's reservoir storage based on historical water use, reservoir data and available groundwater supplies. The model is used to forecast the City's water supply position and to make. certain water policy recommendations. The curve has been updated to reflect the City's current storage. i The model predicts current water storage to last until the late spring of 1996, under a set of worst case conditions. Total storage is approximately at the same level that the City was in early 1987, but the storage at Salinas reservoir accounts for a much higher percentage of the total current storage than was the case in 1987. This is significant as evaporation affects Salinas storage more dramatically, impacting the steepness of the projected storage curve. If drought conditions return next winter, the curve predicts that the City may again enter mandatory conservation in April, 1993. However, a return to normal rainfall patterns next year would increase reservoir storage, especially at Whale Rock. This would continue to pull the City out of the drought and would decrease the necessity of again implementing mandatory water conservation program. i The current increase in reservoir storage does n= influence the City's safe annual yield. CITY OF SAN LUIS OBISPO RESERVOIR STORAGE - FEBRUARY, 1992 A�Pfi� b=ft em.n L"d IM wtuv s L.M at n L-W of rnrrsav Kuw P"J Ym SON l lA es a YA M W I 1Si i 111 1"1 tl! NI LL g WS WS 4” [L 'lrJCj ' L3!'i Q V ' a , flu!ss , ADoIW Pel ,IA � 101 ,ON ,IY .1C HO ,W� llO N T1t• 1�0 ,M rM Nr ,YM .A Y� T1� ,Wr Ir 313192-End of Mandatory Conservation t Actual Level — Predicted Level Figure 6 February 1992- Reservoir Storage Curve 5-8 r,1111111ll1 " 0� l city of San tins OBISp0 COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 8 SUMMARY As is indicated by the storage-curve, the City is still in a very guarded situation in regards to available water supply. In the worst case scenario of continued drought conditions, the City could be back into mandatory water conservation at the beginning of next year. It will take the voluntary cooperation of our water customers and the next year's rainy season to eliminate the need for a mandatory program. It is evident from the curve that the City needs to continue an aggressive water conservation program to extend and maximize existing water supplies. Since no new water supply projects will be completed in the near future, it is possible, lacking adequate rainfall, that the City will be faced with the prospect of water rationing for several years. I SAFE ANNUAL YIELD The safe annual yield of the City's water supply sources is a critical component of water management and is used to determine if adequate water supplies are available for present and future residents. The operation of the City's current water supply system is simulated over the historical period to determine the maximum level of demand or safe annual yield which could be met during the most severe drought period for which records are available. The safe annual yield is the amount of water that can be counted on for supply and can be a constraint to future growth (ie building permits) if supplies are not adequate. The "safe annual yield" of an individual source of water supply is defined as the quantity of water which can be withdrawn each and every year under critical drought conditions and not run out of water or have to implement mandatory water rationing. Safe annual yield analyses of water supply sources are based on the hydrologic conditions (ie. rainfall, evaporation, and stream inflow) experienced during a certain historical period. The period used in the analysis begins in 1943 and is considered appropriate for safe annual yield estimates since the period covers several extreme drought periods, including 1946-51, 1959-61, 1976-77, and 1986-91. The historical period used in the latest computer analysis to determine safe annual yield has been from 1941 through 1991, which includes the recent drought period. Although future hydrologic I conditions will obviously not occur in the precise sequence and magnitudes as have occurred historically, this technique provides an estimate of the future water supply capability of the existing sources if the long-term historical record is considered representative of future conditions. Previous Safe Annual Yield Studies Previous studies of the critical historical drought.periods at Salinas and Whale Rock Reservoirs had indicated the following safe annual yields were available to the City of San Luis Obispo: Water Supply Safe Annual Yield Reference Salinas Reservoir 4,800 afy Corps of Engineers, County (1977) Whale Rock Reservoir' 2,060 afy DWR, (1974) Coordinated Operation 500 afy CH2M-Hill, (1985) 5 411111ull11101111 city of San tins OBlspo Mi COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 9 Groundwater 500 afy 'Vater Operational Plan TOTAL 7,860 afy ' City's share of Whale Rock safe annual yield The safe annual yield analysis for the two reservoirs assumed independent operation and historical data to the date of each report. The critical drought period for these previous studies was 1946-51. The studies also assumed a minimum pool at Salinas and Whale Rock of 400 and 500 of respectively. Coordinated operations is a concerted effort to operate the two reservoirs together for maximum yield. Since Salinas Reservoir spills more often than Whale Rock Reservoir (ie larger drainage area and runoff characteristics) and also has higher evaporation rates, the combined yield from the two reservoirs can be increased by first using Salinas to meet the City's demand and using Whale Rock as a back-up during periods when Salinas is below minimum pool or unable to meet all of the demand. This was a preliminary conservative estimate of the additional safe annual yield which could be obtained under coordinated operation of the two reservoirs. In December of 1988, the City authorized a contract with the engineering firm of Leesdhill- Herkenhoff, Inc. to prepare a detailed analysis of the City's water supplies and an evaluation of the safe annual yield based on coordinated operation of the reservoirs. The report titled "Coordinated Operations Study for Salinas and Whale Rock Reservoirs" was completed in February 1989. The study used hydrologic data from 1941 to 1988 to evaluate the safe annual yield. The study evaluated a number of minimum pool amounts at each reservoir and the impacts of these assumptions on the yield. From this study, assuming coordinated operation, 2,000 of of minimum pool at each reservoir, and 500 afy of groundwater per year, the City's total safe annual yield was estimated to be09, 80 af. Since the City was in a drought period, this amount of safe annual yield was never adopted by Council for planning purposes. It should be reemphasized that this estimate assumed that Whale Rock Reservoir is only used when Salinas is below minimum. pool or can not meet the monthly City demand due to conveyance system limitations and does not consider limitations on the use of Salinas water due I to water quality constraints. Revised Analysis The computer model developed to determine safe annual yield uses only four items of actual historical data. The four items are rainfall, evaporation rates, inflow amounts at each reservoir, and 'five stream" releases. To determine the safe annual yield, the computer operator inputs a value for safe annual yield and the model calculates whether the reservoirs can meet this demand without going below minimum pool. During this iterative process, the program reveals that certain historical periods of time are critical in the determination of safe annual yield (ie reservoirs reach minimum pool). Prior to the recent drought this "controlling period" was from 1946 to 1951. After updating the model to account for the recent drought period, the controlling period is now 1986-1991 for the determination of the City's safe annual yield. A revised estimate of the City's safe annual yield has been performed utilizing data from this controlling period. The City's total safe annual yield from Salinas and Whale Rock Reservoirs, including 500 acre-feet (AF) of groundwater per year, has been estimated to be 7.735 AF The �������►�NI�IIIIIIIIP� ����II city Of San CAIS OBISPO COUNCIL AGENDA REPORT 1992/93 Water Operational Plan Page 10 computer model includes hydrologic information from 1941 to 1991 and uses the following assumptions: ■ Minimum pool at each reservoir is 2,000 acre-feet. ■ 1,000 acre-feet per year is used from Whale Rock to account for periods of water quality problems at Salinas Reservoir (ie. turbid water conditions following storms, etc.). ■ 500 acre-feet per year of groundwater is used as a base flow. ■ Both reservoirs are assumed full at the beginning of the analysis period. Per the Leedshill report, "Following a series of three consecutive wet years from 1941 to 1943, water supply reservoirs can be assumed to be full regardless of the scenario being analyzed. ■ Full estimated storage capacity is available (ie future siltation not accounted for). ■ "Live stream" release rates were estimated using statistical analysis and input for the entire time period to account for the fact that this policy has only been in affect since 1972. I The computer model, with this updated information, now predicts that the City's total safe annual yield is 7.735 acre-feet. As stated previously, the critical period for the calculations is 1986 to 1991. The analysis indicates that if the City water demand was constant each year (7,735 ay) since 1941, Salinas Reservoir would have reached minimum pool in June of 1989 and the City's share of Whale Rock Reservoir would have been 499 of on March 1, 1991. This indicates that if the "Miracle March Rains" had not happened, the City would have run out of water in March of 1991 considering the assumptions listed above. RECOMMENDATION Adopt new City policy reducing the combined safe annual yield by 125 afy, from 7,860 afy to 7,735 afy, utilizing coordinated reservoir operations and 500 of per year of groundwater. Exhibit A: August 1991 Water Action Levels Exhibit B: Reservoir Storage 1986-1992 5-1 I • CITY OF SAN LUIS OBISPO Exhibit August 1991 1991/92 Water Operational Plan ACTION LEVELS Action Level Definition Storage (AF) Entering Exiting Action Levels Action Levels MAX STORAGE Total City's storage in both 45,630 Salinas and Whale Rock Reservoirs STAGE] 3.0 years of supply less annual 21,900 28,100 well capacity plus minimum pool. (15%conservation) STAGE II 2.0 years of supply less annual 13,200 18,200 well capacity plus minimum pool. (35%conservation) STAGE III 1.0 years of supply less annual 6,500 10,000 well capacity plus minimum pool. (50%conservation) Minimum Pool 3,100 The storage levels are based on a base year consumption of 8,050 AFY,and then reduced consumption based on the appropriate conservation goal for each action level,1,800 AFY of well production and minimum pool of 3,100 AF. Entering Action Levels In April of each year, staff will evaluate water supply. If City storage will hit action level within the next nine months,the new conservation level will be implemented in May. Exhibit B cm N .................. ......... Tom .:.................................... CD U. M T T Cc 0 w N Q .......... 0 _.. . . CV (j) rn •� co CD T cy C c L � /c ry�CD�` O T W LL � � C0 v� o o N� L .. ........................... x.. � o s Ln o Ln o 0 o In o U') o (spuesnoyj) }aa�-aa�d