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HomeMy WebLinkAbout09/00/1989, 3-1 - WATER USE AND RESERVOIR STATUS - 9/26/89 - AGENDA ITEM NO. 3 city oson luis om SPO 990 Palm Street/Post Office Box 8100 • San Luis Obispo, CA 93403.8100 September 18, 1989 MEMORANDUM TO: City Counc'1 FROM: P m V City Clerk SUBJ: WATER USE AND RESERVOIR STATUS - 9/26/89 - AGENDA ITEM NO. 3 Acting CAO. :Hike Dolder, requested this be added to the agenda for Tuesday, September 26, 1989 as a Business Item. In order to obtain the most current information, this material will not be available until at least Friday or, possibly, Monday, but he felt strongly that Council should have an opportunity to review and comment on it as part of their discussions with other water-related issues being covered that evening. If you have any questions, please contact Mike or myself. PV:klc DATE �,�,�O�uJIff� l city of San IDIS OBISpo Sete ber :6 198 COUNCIL AGENDA REPORT �"N FROM: William T. Hetland, Utilities Director Ott SUBJECT: Water and Reservoir Status RECOMMENDATION: By motion establish the Monthly City Water Supply Status report, adopt new minimum pool values for the Salinas and Whale Rock Reservoirs and provide additional direction as necessary Background Attached is a methodology for tracking the status of the City's water supply on a monthly basis. Staff has presented this type of information in a number of different ways with the most common being the City's annual water operational plan graph. The approach being presented here takes the initial beginning balance in each of the City's reservoirs and either adds or deducts the various factors that influence reservoir storage and water supply status. Staff first selected each of the factors that need to be included in the equation without assigning specific numeric values. A table was then developed using each of the factors in a logical sequence. This is shown as attachment #1. Monthly City Water Supply Status Beginning of Month Reservoir Status This section starts with the reservoir volumes at the beginning of the month. This is a given number obtained from City records. The minimum pool value is then deducted to determine the available reservoir storage amount (only the City share of the total minimum pool for Whale Rock is used). The minimum pool is influenced by a number of different factors including water quality, physical limitations, and environmental concerns. The following is a range of minimum pool values in acre feet (City share of Whale Rock shown in parenthesis) that have been considered and the justification for each. Salinas Whale Rock Justification A 400 500 ( 275) Dead pool B 2000 2000 (1100) Environmental/Water Quality C 3000 5000 (2750) Water Quality Scenario A represents the dead pool values which are the physical limitation of our ability to withdraw water from the reservoirs. Scenario B represents the best estimate at this time on lowest level where the treatment plant can currently address the water quality concerns. The Whale Rock reservoir also is limited to the 2000 AF level by a 1957 agreement with the California Department of Fish and Game. The agreement does have the flexibility in it to go lower than 2000 AF but that requires some negotiations with Fish and Game. There are no Fish and Game restrictions on the Salinas Reservoir. Scenario C are the currently acceptable minimum pool levels which represent what City staff used to believe was the limiting level for the treatment plant to handle. Since the addition of potassium permanganate and other modifications to the treatment plant, staff is confident that the 2000 AF levels at both Salinas and Whale Rock Reservoirs can be treated to acceptable water quality standards. Staff is recommending that Council adopt these values as current acceptable minimum pools. RCPT nQ SEP 2 51989 cmc MEPIS Q1111PAR1111 city of san tins owpo COUNCIL AGENDA REPORT Page 2 Changes to Reservoir Status The changes to the reservoir status are summarized into three categories. The first is the natural inflow into the reservoirs based on rainfall and runoff. The second is evaporation which is a function of the surface area of the water which also relates to reservoir storage and the weather. The third function is the releases at the reservoirs. Salinas reservoir is required to make releases to meet the live stream requirements for the protection of the downstream water rights users. The Whale Rock Reservoir must make releases to meet its contractual commitments to the Cayucos area water users.. Evaporation is the net evaporation which includes the evaporation off the reservoir and the rainfall on the reservoirs surface. Evaporation is a function of the reservoir level and a measured unit evaporation rate. Rainfall also is a function of the reservoir surface and a measured unit rainfall. The releases are measured by meters at each of the reservoirs and include only downstream releases and does not include spills or water supply diversions. The inflow is a calculated number which takes into account the releases, evaporation, water supply diversions and rainfall. Monthly Water Consumption The monthly water consumption is based on the production at the water treatment plant. This number is adjusted to take into account usage at Cal Poly and Cuesta College. This will be the actual water usage for the City and therefore includes water savings due to conservation activities. Other category includes any miscellaneous water consumption. Additional Sources The additional sources primarily relate to groundwater wells but could also include sources like the one time loan of water from Cal Poly. The amount of water attributed to groundwater wells is the actual amount that is currently going into the water system. This amount of well water for any given time can be determined from City records. There are currently four domestic wells operational. The well at the Corp Yard which provides construction water and the two irrigation wells (Laguna Lake Golf Course and Mitchell Park) are not included in this analysis since their water use is included in the water consumption figures as part of the conservation effort. The four domestic wells and their production are as follows: Groundwater Wells Fire Station #4 80 gpm 128 AFY Pacific Beach #1 205 gpm 330 AFY Dalidio 550 gpm 885 AFY Range/Reservoir #1 60 eom 97 AFY Total 895 gpm 1440 AFY The groundwater well production averages about 120 AF per month. Since the City is continuing to develop additional groundwater wells these values will change over time. The other category involves any miscellaneous water that should be considered in the analysis. I 11j$VA, �j city of san tins 0Blspo COUNCIL AGENDA REPORT Page 3 Reservoir Storage Curve At the bottom of the second page of the Monthly City Water Supply Status will be a graph which will track the reservoir storage. This will be a visual representation of the above data. The graph will also indicate the different action points (minor, moderate, severe and critical) that were established as part of the Annual Water Operational Plan. Staff is currently putting the graph on the computer and will have the graph ready for the September report. RECOMMENDATION Staff recommends that Council adopt by motion new minimum pool values of 2000 AF for both the Salinas Reservoir and the Whale Rock Reservoir. It is further recommended that the Monthly City Water Supply Status report be established to track the City's water supply. I 3.3 i City of San Luis Obispo Monthly City Water Supply Status (All figures in Acre Feet) Effective Date Beginning of Month Reservoir Status Salinas Reservoir Less Minimum Pool Net Available Whale Rock Reservoir Less Minimum Pool Net Available Available Reservoir Storage Changes to Reservoir Status Salinas Reservoir Inflow Evaporation Releases Net Change in Salinas Whale Rock Reservoir Inflow Evaporation Releases Net Change in Whale Rock Total Reservoir Changes Total Available Reservoir Storage _ C 3�� r i City of San Luis Obispo Monthly City Water Supply Status Page 2 Monthly Water Consumption Plant Production Other Net Consumption Additional Sources Groundwater Wells Other Total Additional Sources End of Month Total Reservoir Storage - End of Month Salinas Storage End of Month Whale Rock Storage ��J _ � CL' •' J..Dc V �oUuI�.L S 0 LUIS OBISPO COURTY COUNTY GOVERNMENT CENTER • SAN LUIS OBISPO,CALIFORNIA 93408 • (805)549-5252 GEORGE C. PROTOPAPAS County Engineer 4110 CUNT014 N1M COUNTY DEPUTY CGUNIV ENGINEER ENGINEERING N=KM SPECDISTRICTS AD R OR E C E I V E® DEPARTMENT S ROADS TRANSPORTATION September- 25, 1989C � FLOOD CONTROL CCCO 4Q SEP 5 1 (� WATER CONSERVATION COUNTY SURVEYOR CITY CLERK SPECIAL DISTRICTS Mayor Ron D u n i n SAN LUIS OBISPO,CA SOLID WASTE City of San Luis Obispo P. 0. Box 8100 San Luis Obispo, CA 93403-8100 Subject : Salinas Reservoir - Minimum Pool Dear Mayor Dunin: Confirming our discussion at the meeting on September 25, 1. 989 we, as operator of the Salinas River Dam Project for the U. S. Army Corps of Engineers , have no objection if the City of San Luis Obispo desires to set the minimum pool at 2000 acre-feet this year in light of the present water situation in the City.. By letter dated December 23, 1988, Glen Priddy, our Hydraulic Operations Engineer, had advised Bill Hetland that we were unable to find any U. S. Army Corps of Engineers' requirement for a minimum pool . Our concern, as operator of the project , would be that the reservoir not be: completely dewatered for fear that a high intensity storm would wash sediments against the outlet works with the chance of them then becomimg inoperable. A 2000 acre-foot minimum pool should provide adequate protection that such would not occur. As you recognize, you may expect continuing degradation of the water quality as the reservoir storage continues to drop. City staff is well aware of this and can take appropriate steps in treatment to make the water suitable for meeting drinking water standards. We also indicated in our December 23, 1988 letter to Bill Hetland, that the State Department of Fish and Game had expressed interest f in the minimum pool in connection with preservation of the fishery . Sincerely, GEORGE C. PROTOPAPAS County Engineer lw/' 4 CLINTON MILNE Deputy County Engineer M/ras cc : Bill Hetland Utilities Manager 86302 �i►II I III Illlll III I ���������Illhllll I I II � II® CityO San luis OB 1Sp0 990 Palm Street/Post Office Box 8100 • San Luis Obispo, CA 93403-8100 September 25, 1.989 M E M O R A N D U M TO: City Council FROM: am s SUBJECT: Ite 413 - September 26, 1989 meeting Attached is --a.: Monthly City Water Supply Status sheets received by the City Clerk's Office on Monday, September 25, 1989. Acting City Administrative Officer, Mike Dolder requested this item be provided to you for Item 413 for Tuesday, September 26 City Council meeting dealing with this issue. He apologizes for its lateness. Any questions you may have, please call Bill Hetland or myself. Thank you. Pv:ljh att. cc: CAO Attorney B. Hetland B. Statler Telegram-Tribune �EnNG AGENDA DATE 9 ITEM it City of San Luis Obispo Monthly City Water Supply Status (AU figures in Acre Feet) Effective Date 8-31-89 Beginning of Month Reservoir Status ! Denotes acdon by Lead Person Salinas Reservoir 4,161.9 Resound by. ncil Less Minimum Pool 2.000.0 AO ity Atty. Net Available 2,161.9 ((fit GteAcLL-oJJ-ii.g//// Whale Rock Reservoir 10,996.6 ,(4.S'�ir.5�/�r-,.:. Less Minimum PoolNet --- Net Available 8,996.6 Available Reservoir Storage 11.158.5 Changes to Reservoir Status Salinas Reservoir Inflow _75.4 R E C 91 y" (205.1) 2l. 20 pV Evaporation - Releases (60.4) ctty.CLERK �'P�1 k4yg Q9ISPSL�. Net Change in Salinas (1 an_1) Whale Rock Reservoir Inflow (0.5) Evaporation (179,9) Releases (47.9). Net Change in Whale Rock (228.3) .Total Reservoir Changes (418.4) Total Available Reservoir Storage 10,740.1 City of San Luis Obispo Monthly City Water Supply Status Page 2 Monthly Water Consumption Plant Production (488:5) Other 66.2 Net Consumption (422.3) Additional Sources Groundwater Wells 42.8 0 Other Total Additional Sources 42'8 10,360.6 End of Month Total Reservoir Storage End of Month Salinas Storage 39793.4 End of Month Whale Rock Storage 10,567.2 1 Revised 9/22/89 ADJOURNED REGULAR MEETING TUESDAY, SEPTEMBER 26, 1989 - 7:00 P.M. ADDED BUSINESS ITEM: 4. METER READING SCHEDULE (STATLER) Consideration of Janet Kourakis' concerns with the schedule for reading meters in her area. RECOMMENDATION: No action is recommended on this item. (Agenda report will be distributed under separate cover.) (Item added on Friday, September 22, 1989 at 4:00 p.m)