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HomeMy WebLinkAbout01/02/1990, 3 - WATER AND RESERVOIR STATUS MEn I��NNI�IIIIyIIIIIIIIIIaIIuIII r Janu G DATE: I���ui► Ci o san lues OBISpo Januar 2 1990 COUNCIL AGENDA REPORT 1TEM NUMBER: 61 FROM: William T. Hetland, Utilities Director SUBJECT: Water and Reservoir Status RECOMMENDATION: By motion adopt new minimum pool values for the Salinas and Whale Rock Reservoirs BACKGROUND Reservoirs have established minimum pool values. A minimum pool represents the lowest storage level at which a reservoir would be operated. There are a number of factors that influence the establishment of a minimum pool. These factors include water quality, physical limitations, low water level impacts on fisheries and environmental concerns. The City of San Luis Obispo had the consulting firm of Leedshill-Herkenhoff Inc. perform a study on the combined operations of the Salinas and Whale Rock Reservoirs. The basic purpose of the study was to determine the increase of the safe annual yield if the two reservoirs were operated in a combined manner. During this analysis the consultant reviewed the initial safe annual yield study performed by the State Department of Water Resources on the Whale Rock Reservoir. The analysis was performed based on different minimum pool values. The San Luis Obispo City Council accepted 5000 acre feet as the minimum pool value for Whale Rock Reservoir and 3000 acre feet for Salinas Reservoir at the time the Leeds hill-Herkenhoff report was issued. On September 26, 1989 the City staff recommended new minimum pool values of 2000 acre feet for each reservoir be adopted. This would result in more water being available to the City and delay the time that more stringent water conservation measures would have to be enacted. The Council felt that the Whale Rock Commission was the more appropriate agency to make the minimum pool determination for the Whale Rock Reservoir. The Council directed City staff to bring this issue to the Whale Rock Commission. On November 27, 1989, the Whale Rock Commission formally adopted a minimum pool value for the Whale Rock Reservoir of 2000 acre feet. ALTERNATIVES 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 basic justification for each. Alternative Salinas Whale Rock Justification A 400 500 ( 275) Dead pool B 2000 2000 (1100) Environmental/Water Quality C 3000 5000 (2750) Historical/Water Quality Alternative A represents the dead pool values which are the physical limitation of our ability to withdraw water from the reservoirs because of intake structure limitations. Alternative 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 to go lower than 2000 AF requiring some negotiations with Fish and Game to mediate any potential adverse impacts on the fisheries. There are no Fish and Game restrictions on the Salinas Reservoir. Alternative C represents the currently acceptable minimum 3-/ ���N�►�uuulllllllllp q�NlU city of San Luis OBIspo COUNCIL AGENDA REPORT Minimum Pool Values for the Salinas and Whale Rock Reservoirs January 2, 1989 Page 2 pool levels which City staff believed to be 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 based on the City's experience in treating Salinas Reservoir water. Staff is recommending that Council adopt these values as current acceptable minimum pools. Adoption of alternative B would result in the City's minimum pool values being 3100 acre feet instead of the current value of 5750 acre feet. This results in 2650 acre feet of water being available for use. This represents approximately 4 to 5 months of additional consumption for the City at its current rates. The critical action level (one year supply less annual well capacity plus minimum pool), where city policy requires a 50% water conservation level, would go from the current value of 9,830 acre feet to 7,180 acre feet. Reservoir storage as of December 1, 1989 was 12,762 acre feet. CONSEQUENCES OF NOT TAKING THE RECOMMENDED ACTION If the minimum pool values are not modified as recommended, the City could reach its critical levels in the reservoir sooner and be required to implement 50°x6 water conservation earlier (should drought conditions continue). The minimum pool values also have an influence on the safe annual yield calculations if those were to be revised once the reservoirs become full again. FISCAL IMPACT There is no direct fiscal impact as a result of changing the minimum pool values. 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. Attachments: Action Level Comparison November 27, 1989 Whale Rock Commision Report and Minutes R\Bill\whminpoolwp COMPARISON LEVELS COMPAISON C; Based on Revised Minimum Pool Levels City of San Luis Obispo December 1989 METHODOLOGY 1. 2. Assumptions: Annual Consumption(AFY) 5400 5400 Weil Production (AFY) 1320 1320 Minimum Pool (AF) 5750 3100 Action Level Definition Storage.(AF) M1NOR 66°x6 of Reservoir Storage less annual well capacity 28,831 28,831 (5% conservation) MODERATE 2:5 years of supply less annual well capacity plus minimum pool 15,950 13,300 (15% conservation) ,.@VERE 2.0 years of supply less annual well capacity plus minimum pool 139910 11,260 (25% conservation) CRITICAL 1.0 years of supply less annual well capacity plus minimum pool 9,830 7,180 (50% conservation) 1. Current Methodology With Conservation and Wells - Storage levels are based on the City's share of existing reservoir storage, well production and water consumption including water conservation. These storage levels can change as consumption, conservation, well production, and minimum pools values vary. This is the most up-to-date information and is recommended for use by the Council in making future policy decisions. 2. Current Methodology With Conservation, Wells, and Revised Minimum, Pool Levels - Storage levels are identical to the above except that the proposed minimum pool levels of 3100 acre feet are used. U N\ACTIONLE ��� MEETING DATE: ovemher 2 1989 WHALE ROCK COMMISSION REPORT 'TEM"UzaER: FROM: William T. Hetland, Utilities Director�v { SUBJECT: Establishing A Minimum Pool Level for Whale Rock Reservoir BACKGROUND: Reservoirs have established minimum pool values. A minimum pool represents the lowest storage level at which a reservoir would be operated. There are a number of factors that influences the establishment of a minimum pool. These factors include water quality, physical limitations, low water level impacts on fisheries and environmental concerns. The City of San Luis had the consulting firm of Leedshill-Herkenhoff Inc. perform a study on the combined operations of the Salinas and Whale Rock Reservoirs. The basic purpose of the study was to determine the increase of the safe annual yield if the two reservoirs were operated in a combined manner. During this analysis the consultant reviewed the initial safe annual yield study performed by the State Department of Water Resources on the Whale Rock Reservoir. The analysis was preformed based on different minimum pool values. These values were based on factors listed above and are identified below. Minimum Pool Justification 1. 500 Acre feet Dead pool 2. 2000 Acre feet Environmental/water quality 3. 5000 Acre feet Historical/Water Quality The dead pool represents the lowest physical level that water can be withdrawn from the reservoir because of the intake structure limitation. 2000 acre feet is the City staff's current best estimate at which the treatment plant is able to produce a high quality water for the consumers. It is also the minimum pool level identified in the Commission's 1957 agreement with the California Department of Fish and Game. Though, the agreement does have the flexibility to go lower than 2000 acre feet, but requires negotiations with the Department of Fish and Game to mediate any adverse impacts to the fisheries. The 5000 acre feet minimum pool was a historical value based in part on the initial level that the staff felt could be treated at the treatment plant. Since that time additional process units have been added to the treatment plant(ie. potassium permanganate) which will allow the plant to effectively treat to at least 2000 acre feet based on the City's experience with treating the Salinas Reservoir water. ' The San Luis Obispo City Council accepted the 5000 acre feet as the minimum pool value at the time the Leedshill-Herkenhoff report was issued. On September 26, 1989 the City staff recommended that a new minimum pool value of 2000 acre feet be adopted. This would result in more water being available to the City and delay the time that more stringent water conservation measures would have to be enacted. The Council felt that the Whale Rock Commission was the more appropriate agency to make the minimum pool determination. The Council directed City staff to bring this issue to the Whale Rock Commission. The Leeds hill-Herkenhoff report and the Department of Fish and Game agreement are available in the Utilities Department office at 955 Morro Street for review. Recommendation Staff recommends the Whale Rock Commission establish 2000 acre feet as the minimum pool value for the Whale Rock Reservoir. 3-� DRAFT MINUTES WHALE ROCK COMMISSION MEETING Monday, November 27, 1989 Hearing Room, City Hall - 990 Palm Street San Luis Obispo, California COMMISSION MEMBERS PRESENT : Doug Gerard, California Polytechnic State University Commission Chair Ron Dunin, City of San Luis Obispo, Commission Vice Chair Carlos Madrid., California Dept. of Water Resources Penny Rappe, representing Commr . John Dunn Carmen Salvato, California Mens Colony William Statler , City of San Luis Obispo COMMISSION MEMBERS ABSENT: John Dunn, City of San Luis Obispo , Commission Secretary CITY STAFF PRESENT: Barry Daffern, Water Supply Supervisor William Hetland, Utilities Director Allen Short , Water Division Manager Lisa Woske, Recording Secretary ROLL CALL Chairpman Doug Gerard called the meeting to order at 1: 30 p.m. and invited comments from the audience in accordance with the Brown Act (items not on the agenda) . Paul Enns, Paso Robles Beach Water Assoc . representative, asked that his association obtain more . water as downstream users to relieve the building moratorium in Cayucos . The Commission discussed methods in which Cayucos could be better provided for development and how to find other sources. Mr . Enns stated that that the Morro Rock Mutual and Water District 18 were also interested in consolidating the districts into one body. He asked that better source communication occur so property owners in the north county could build. ACTION ITEMS 1. Draft Minutes from June 13., 1989 . There were a couple ty"pographical errors corrected. Commr. Madrid moved to approve the minutes as corrected. Commr. Dunin seconded the motion. Motion carried. 3-� r-- Whale Rock Commission Meeting November 27, 1989 Draft Minues Page 2. 2. Establishing a Minimum Pool Level for Whale Rock Reservoir Bill Hetland discussed the staff report on the minimum pool leve , physical limitations, and water quality impacts. He stated there was no policy as yet and discussed the Agreement with the Dept . of Fish and Game. He discussed the cooperative use arrangement and using the Salinas Reservoir as a primary source and the Whale Rock Reservoir as a secondary source. He stated City Counil wanted a policy from the Commission to establish a minimum pool levels. He further discussed the staff-outlined Alternatives and the ability to treat water down to the 2000 level . He stated that the storage percentage would remain intact, but the actual storage capacity would change. Staff recommended the Whale Rock Commission establish 2000 acre feet as the minimum pool value for the Whale Rock Reservoir. Commr. Salvato moved to accept the staff recommendation . Commr. Dunin seconded the motion. The motion passed unanimously . 3 . Well Facilities Operation and Agreement Update for the Cayuaos Area Water Organization . Allen Short presented the staff report and the process of examining the pumping procedure and the pump use. He discussed the fifth and final draft of a document to transfer ownership to the CAWO . He stated the City would be obligated to drill another well or treat the existing water . He discussed the . iron and manganese levels of the wells and subsequent treatment. . Barry Daffern discussed the •lack of inflow and the obligation parameters and responsibilities of the City. Staff recommended the .•Commission receive and file the report , with applicable staff direction. Chairman Gerard stated he wanted the document to outline a 600 acre foot maximum. ; Commr. Salvato felt the document language should be revised in terms of indicating past-tense for aspects already accomplished. Commr..'", Madrid felt the CAWO should be listed specifically , as opposed to as "users" and that the use charges per Agency should be included ir�the Agreement .