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HomeMy WebLinkAbout03/20/1989, 3-A - CONSIDERATION OF LEEDSHILL-HERKENHOFF PROPOSAL TO STUDY THE IMPACTS OF DOWNSTREAM WITHDRAWALS ON TH MEETING DATE city of san Luis owpo March 14 1989 COUNCIL AGENDA REPORT I w =` FROM: William T. Hetland U01 PREPARED BY: Allen Short Utilities Director Water Division Manager SUBJECT: Consideration of Leedshill-Herkenhoff proposal to study the impacts of downstream withdrawals on the Salinas River "live stream" releases. RECOMMENDATION: Adopt resolution approving the proposal with Leedshill-Herkenhoff to study the impacts of downstream withdrawals on the Salinas River "live stream" releases. BACKGROUND: The City retained. the firm of Leedshill-Herkenhoff to perform a safe annual yield study and a coordinated operations study for Salinas and Whale Rock Reservoirs. The scope of the project was to determine, based upon the best available data, information, and simulated model projection, the City's safe annual yield for water supply planning purposes. To accomplish the project a model was developed based upon actual; Rainfall measurements, Evaporation measurements and calculations, Hydrologic data, Reservoir inflows and outflows, Statistical correlations. In addition, a number of minimum storage level scenarios were identified and analyzed in the operations model developed by Leedshill-Herkenhof:f. Based upon the findings and conclusions developed during the course of the study, a number of recommended actions were identified. One of the actions was the following; To verify the safe annual yield estimates for Salinas Reservoir, the downstream hydrologic conditions should be investigated for their potential impact on the magnitude and duration of reservoir releases required to meet the provisions of the "live stream" agreement. Staff prepared a Council Agenda Report summarizing the Leedshill-Herkenhoff study and the steps staff undertook to maximize the safe annual yield from the City's existing reservoirs. The Leedshill-Herkenhoff study recommended that it may be possible to increase the safe annual yield value from its current level. However, pending an investigation and study concerning the impact of downstream withdrawals on the Salinas River "live stream" releases, staff recommended to the City Council that no adjustment to the City's safe annual yield be made at this time. 3/ A _ city Of San WIS OBISPO COUNCIL AGENDA REPORT Page 2 To provide the City Council and Staff with the essential information needed to recommend and adopt long term water planning decisions, the downstream water use and "live stream" releases must be addressed. Staff contacted Leedshill-Herkenhoff and requested that they assemble a proposal to study the "live stream" issue. As a result, a number of factors have been identified as possibly having an impact upon the "live stream" requirement and require further investigation. They are listed below; Hydrologic data should be monitored and analyzed, Inflow vs storage, and release ratios, Dam Operations, Downstream changes, Actual water rights. In addition, as the North County develops in size, the amount of groundwater pumping along the Salinas River has also increased. This additional pumping may be causing increases in reservoir releases which, in turn, may be decreasing the City's safe annual yield from Salinas Reservoir. The firm of Leedshill-Herkenhoff has prepared a proposal outlining the scope of work and associated fee estimates for conducting a study of the potential impacts that increased downstream water use may have on "live stream" releases. i Under this proposal the consultant will perform work in phases as necessary to try and answer the problem. This will minimize cost and expedite the work. There is the potential that at this proposed level of work the consultant will not be able to reach a final conclusion and that additional work may be necessary. This may include extensive basin modeling which may involve hundreds of thousands of dollars. Before that decision is reached, Council would have to review all available information and make a determination on the cost effectiveness of further study. CONSEQUENCES OF NOT TAKING ACTION: If the study does not proceed forward; The City will continue to operate in the status quo. The impact of the downstream use will continue to be unknown. The inflow vs storage ratios will continue to be a concern and the actual operations unknown. The City's share of the safe annual yield may continue to decrease to meet the "live stream" requirement. i FINANCIAL IMPACT: i Base proposal $16, 900. 00 Total $16,900. 00 IM I City Of san Luis OBisp0 COUNCIL AGENDA REPORT Page 3 Adequate funds are available in the water fund budget. Additional funding may be necessary if the outcome of this study shows more work is required to clearly answer the concerns with the live stream. RECOMMENDATION• Adopt resolution approving the proposal with Leedshill-Herkenhoff to study the impact of downstream users on the "live stream" releases. APPROVED: ity A ministrative Officer City At y Finan D' ector Utilities Director I RESOLUTION NO. (1989 SERIES) A RESOLUTION OF THE COUNCIL OF THE CITY OF SAN LUIS OBISPO APPROVING THE PROPOSAL WITH LEEDSHILL-HERKENHOFF, INC. , TO STUDY THE IMPACTS OF DOWNSTREAM WITHDRAWALS ON THE SALINAS RIVER "LIVE STREAM" RELEASES WHEREAS, the City of San Luis Obispo performed a safe annual yield study and a coordinated operations study for Salinas and Whale Rock Reservoirs; and WHEREAS, the City retained the firm of Leedshill-Herkenhoff, Inc. to perform this study; and WHEREAS, one of the findings and conclusions developed during the study was to investigate the downstream hydrologic conditions for their potential impact on the magnitude and duration of reservoir releases; and C' WHEREAS, this is considered essential information needed to recommend and adopt long term water planning decisions. NOW, THEREFORE, BE IT RESOLVED that the Council approves the proposal with Leedshill-Herkenhoff, Inc. to study the impact of downstream users on the Salinas River "live stream" releases, in the amount of $16,900. On motion of seconded by and on the following roll call vote: / AYES: NOES: ABSENT: the following resolution was passed this day of C 1989 . r Opage 2 Resol. No. MAYOR RON DUNIN ATTEST: CITY CLERK PAMELA VOGES Approved: ity A inistrative Officer City Attorney C Finance D' ctor Utilities Director downstream/cas O �-s LEEDSHILL-HERKtNHOFF, INC. 30.1 Second Street,Suite 880 North San Francisco,California 94107 415243.9980 March 2, 1989 Mr. William T. Hetland Utilities Director City of San Luis Obispo 955 Morro Street San Luis Obispo, CA 93401 Subject: Study of Impacts from Downstream Water Use on Salinas Reservoir "Live Stream" Releases - Proposal for Professional Services Dear Mr. Hetland: As you requested, LEEDSHILL-HERKENHOFF (LH) has prepared the attached out- line of the required work and associated fee estimate -for conducting a study of the potential impacts that increased downstream water use may have on the "live stream" releases from Salinas Reservoir. The main objective of this study is to identify whether a relationship exists between downstream water use and reservoir releases and, if possible, to quantify the rel.ationship. O If conclusive "answers" are found, the results from this study can be used to provide the CITY with a more reliable estimate of the safe annual yield that can be developed from Salinas Reservoir. As noted in the attachment, a conclusive determination of the impacts from increased downstream water use on the "live stream" releases will be ex- tremely difficult due to the size and complexity of the hydrologic basin and the limited historical data available. Therefore, in addition to the pro- posed work outlined in the attachment, a considerable amount of additional study may be needed to provide conclusive results. Because of our extensive recent work for the CITY, we are able to take advantage of our existing knowledge and familiarity with the water supply operations at Salinas Reservoir. Based on this knowledge and experience with similar work, LH has developed the attached outline of the required tasks. Our fee estimate for this work is based on our Standard Schedule of Fees and projections of the number of staff hours needed to complete each task. Each primary task and its associated budget are listed on the following sheet. SAN FRANCISCO SAN DIEGO • DENVER • ALBUOUEROUE • SANTA FE • PHOENIX �� (� _ LM LEEDSNILL•NERKENNOFF. INC. Mr. William T. Hetland March 2, 1989 Page 2 TASK NO. DESCRIPTION ESTIMATED FEE PHASE I (1) Data Collection $ 21,600 (2) Prepare Base Map 19900 (3) Interview Water System Operators 1.600 SUBTOTAL $ 69100 PHASE II (1) Analyze Trends and Changes $ 41200 (2) Evaluate Interrelationships 3,800 (3) Prepare Report 2.800 SUBTOTAL $10,800 --'� TOTAL FEE $16,900 Because of the uncertain nature of the work, LH would suggest conducting the work on a "time and materials" basis with total billings not to exceed 516,900 without the CITY's authorization. If the work is approved and notice to proceed is provided, we anticipate being able to complete this work within 4 to 6 weeks. Please do hesitate to call Mark Williamson or me if you have any questions regarding our proposal . We appreciate the opportunity to again work with the CITY and look forward to assisting in this important investigation. Respectfully submitted, LEEDSHILL-HERKENHOFF, INC. Robert 0. Sverak Senior Engineer Attachment htlnd.m2/rosbd3 1 MLEEDSNILL•NERKENNOFF. INC. O STUDY OF IMPACTS FROM DOWNSTREAM WATER USE ON SALINAS RESERVOIR "LIVE STREAM" RELEASES Outline of Work Tasks The availability of water supplies from Salinas Reservoir has been adversely impacted in recent years by increased releases necessary to meet the re- quirements of the "live stream" agreement. Increased downstream water use, particularly groundwater pumping from the river alluvium, may- be increasing the length of the release period and, therefore, the quantities of required release. If so, even higher "live stream" releases may be expected in the future, thereby decreasing the water available for diversion to the City of San Luis Obispo. Because of the size and complexity of the hydrologic basin and the limited availability of data, it will be difficult to quantify the exact impact that increased downstream water use in the downstream reaches has on the "live stream" releases. However, through careful review of available records and statistical comparisons of hydrologic patterns, it may be possible to iden- tify certain trends or relationships between the natural hydrology (i .e. , rainfall and streamflow) , "live stream" release requirements, and the rate and timing of downstream water use. Therefore, the purpose of this study is to identify and, if possible, quantify the impacts of downstream water users on the flow of the Salinas River and the associated reservoir releases. Depending on the results of the investigations, conclusive answers may be found early in the study or, alternatively, may not surface without further analysis. Due to the uncertain nature of the work, LEEDSHILL-HERKENHOFF (LH) recommends that the study be conducted using a phased approach in order to minimize the cost to the CITY. Following completion of each phase, LH will report our findings to the CITY. Accordingly, LH has developed the following outline of tasks for the first two phases of the study based on our existing understanding and knowledge. Additional studies that may be necessary or desired in subsequent phases cannot be determined until comple- tion of these preliminary phases. Following completion of Phase II, LH will provide recommendations for additional studies based on the findings of our investigations. PHASE I - BACKGROUND INVESTIGATIONS The first phase will provide the necessary background information and data to perform the subsequent analyses in second phase in an . efficient manner. The tasks to be conducted in Phase I include data collection and review, Mapping, and interviews with operators and other officials. Three tasks have been identified for the Phase I study, and are detailed below. MIEEDSXILL-NENKENXOFF.MC. _ Task 1 : Data. Collection. For this task, available data pertinent to water flows and extractions will be collected and" summarized from various agencies. This data will include the following: a. Well locations, capacities, depths, and ownership as registered with the State Water Resources Control Board, State Department of Water Re- sources and San Luis Obispo County. b. Historical groundwater level data available from DWR, SLO County, and in published reports. C. Monthly well production' records since adoption of the "live stream" agreement in 1971. These records should be available from municipali- ties along the Salinas River. Estimates of groundwater pumping for irrigation adjacent to the Salinas River will be made from published acreage reports, known pump capacities, and typical application rates. d. A closer analysis of. the monthly operating records collected during our previous studies will be conducted, including use of daily records.. e. Stream gaging records available from USGS will be compiled for all stations tributary to the Salinas River upstream of Nacimiento River. This information is available on our in-house HYDRODATA computer sys- tem. f. Reports available from the City, County, or other agencies will be used to minimize duplication of effort. The May 1958 DWR Bulletin No. 18, "San Luis Obispo County Investigation", which includes geologic and well information, and the previous 1975 report on the live stream agreement will provide valuable information. g. Rainfall over the entire period of record for all basin gages, some of which has been collected in' our previous studies, will also be required. h. Records of historical irrigated acreages will be necessary to determine the extent of agricultural water use. i . Water rights information will be reviewed to determine all primary water users along the affected reach of the river. Task 2: Prepare Base Map. For this task, a map of the upper portion of the Salinas River basin will be prepared to assist in analyzing basin-wide hydrology. This map will include basin and .sub-basin boundaries, geologic features including aquifers and C� �- 9 1 WLEEDSHILL•HERKENHOFF. WC. Cfaults to the extent known, and the location of stream gages and wells. The observation points for the "live stream' agreement will also be plotted for comparison to locations of groundwater wells. Task 3: Interview Water System Operators. For this task, interviews will be conducted with the Salinas Dam operator and downstream municipal and agricultural well operators. Operators will be queried about past and present practices. In particular, the exact method for determining Salinas Dam releases will be established. Any records of observations will be obtained to substantiate the operation methodology. PHASE II - ANALYSIS AND REPORT In Phase II, LH will conduct statistical analyses to identify obvious trends or changes over the past twenty years or possible relationships between hydrologic variables and water use. The Phase II analyses will be better defined following completion of Phase I but will likely include close in- spection of historical data, water rights quantification, comparative plotting of historical data, various correlation analyses, formulation of hydrologic budget or water balances, analysis of surface/groundwater interconnection, or other analyses suggested by the information collected in CPhase. I . The extent of the required work effort for Phase II will vary dramatically depending on the information derived in Phase I and the results of preliminary analyses. Based on our current projections of the antici- pated work, LH has budgeted $10,800. If the scope of the work changes significantly following Phase I, LH will revise our fee accordingly. Three tasks have been identified for Phase II, and are detailed below. Task 1 : Analyze Trends and Changes in Water Supply and Use. A preliminary analysis of the data will be made in this task by tabulating and plotting the data collected in Phase I. A close inspection of the data will allow immediate identification of profound trends or shifts in natural or man-induced water movements, and will allow determination of annual patterns of inflow and water use. This analysis will be performed on an annual , monthly, or daily basis, as appropriate, for the following aspects: a. Natural factors including rainfall within the watershed, inflow to Salinas Reservoir, flow in the Salinas River flow at Paso Robles and the flow in other gaged streams. b. Man- influenced factors including groundwater pumping tabulated by sub- basin or aquifer, groundwater levels in selected key wells repre- sentative of an area, stream flow diversions, and releases from Salinas Reservoir. C� MLEEDSMILL•MERKEMMOFF. INC. - C- Task 2: Evaluate Interrelationships between Hydrologic Variables and Uses In this task, the interrelationships between the natural water supply and the various uses in the downstream reaches will be explored, and preliminary conclusions postulated. A rough accounting of the hydrologic balance will be performed by comparing upstream surface flows at Salinas Reservoir to downstream gages -such as "Salinas River at Paso Robles," and by comparing groundwater pumpage and groundwater levels. Numerous statistical correla- tion analyses will be conducted among the various factors to determine if a relationship exists between flows, releases, and groundwater pumpage. If possible, such relationships will be quantified. Task 3: Prepare Report and Recommend Further Studies. The methodologies and results of the above tasks will be summarized into a brief report for presentation to the CITY. This report will contain suffi- cient basic data and explanation of assumptions to lead the reader through the analysis. Preliminary conclusions will be reported and recommendations for further study detailed. tasklist/mswWorkl l � U city of San Luis OBispo WrCTW. 1989 A COUNCIL AGENDA REP®RTff 14,001 FROM: William T. Hetland PREPARED BY: Allen Short Utilities Director Water Division Manager SUBJECT: Salinas Reservoir Update RECOMMENDATION: Receive and file report. Direct staff to continue their efforts in maximizing the yield of both water supplies. BACKGROUND: Staff, for the February 7, 1989 City Council meeting, prepared a Council Agenda Report detailing the Leedshill-Herkenhoff Coordinated Operations Study for the Salinas and Whale Rock Reservoirs. Also contained in that report was a section dealing with the water quality concerns at Salinas Reservoir. At the time of the report, Staff was pursuing a number of alternatives that would allow the City the use of the water in Salinas Reservoir. Listed below is a summary of the concerns and the implemented solutions: 1. Treatment - The primary concerns of the Salinas Reservoir water source were due to taste and odor problems, and high manganese levels. Staff has experimented with potassium permanganate at the laboratory level. All laboratory analyses demonstrated that these problems are greatly reduced by the application of potassium permanganate. Staff has been applying this chemical at the plant level since February 28, 1989 and at this point all indications are positive that we can treat water down to the 2000 to 3000 acre foot storage level. 2 . Intake - A second problem identified at the Salinas Reservoir was the lack of flexibility when obtaining water at the lower levels of the lake. Staff has designed and fabricated an intake "tube" which is scheduled to be installed the week of March 20, 1989. The installation of the intake tube will allow staff the ability to select the level at which the water quality is the best and most economical to treat. The steps taken above will help provide staff with the tools required to maximize the yield from Salinas Reservoir. Since March 3, 1989 we have been treating 100% Salinas water with no customer complaints. Staff will continue to monitor the operations and make adjustments throughout the season as conditions change to maximize water use and quality. -` RECOMMENDATION.: Receive and file report. Direct staff to continue it's efforts in maximizing the yield of both water supplies.