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Home My WebLink About; Lake Calavera & Mission Basin Well Field; Lake Calavera & Mission Basin Well Field; 1984-04-14A REPORT ON THE EVALUATION OF LAKE CALAVERA AND MISSION BASIN WELL FIELD AS WATER RESOURCES CITY OF CARLSBAD APRIL Ht, 198*f A REPORT ON THE EVALUATION OF LAKE CALAVERA AND MISSION BASIN WELL FIELD AS WATER RESOURCES I. SCOPE OF STUDY The scope and purpose of this study is to evaluate Lake Calavera and the well field located in the "Mission Basin " (basin) as to their potential for integration into the water system of the City of Carlsbad or, in the alternative, to recommend other utilization of these assets. The study consisted of field inspections, discussions with the Water Utilities Director of Oceanside, consultation with expert hydrogeologists and examination of all available reports relative to the subject areas, including some furnished by the City of Carlsbad. All major water rights, appropriation, diversion licenses and permits were investigated. Special thanks is given to Roger Greer, Director Utilities/Maintenance of the City of Carlsbad for his time and assistance, as well as Jim Turner, Water Utilities Director, City of Oceanside, and Bob Coates, Project Manager. — 2 — II. DESCRIPTION OF FACILITIES A. LAKE CALAVERA The City acquired Lake Calavera and a permit to divert 150 acre feet of water from Calavera Creek from the Carlsbad Mutual Water Company. The original license was for irrigation purposes, later changed to recreational and fire protection purposes. In addition to the water rights of the lake, the City owns some 252 acres of land. The lake is currently used in a marginal manner for flood control, but no beneficial use of the water is presently made. The property is surrounded on the west side by residential developement and appears to lend itself to such developement. Utilities are available nearby to serve the property and improved streets provide access. The topography is gently rolling, sloping generally toward the lake near its center. B. WATER RIGHTS The City owns a series of wells, "sump" pumping station and transmission facilities for the production and delivery of water from the "Mission Basin" of the San Luis Rey River Valley in eastern Oceanside. The City has rights to 2,382 acre feet of water from the basin traceable to 1914. In addition, the City holds a license (terminable by the State Division of Water Rights, Department of - 3 - Water Resources, from year-to-year) for another 1,000 ACFT. This basin was historically the site of large truck farms and citrus orchards. Groundwater pumped from the basin was used extensively for irrigation and for export to the Cities of Carlsbad and Oceanside. Since the 1950's , pumpage has declined considerably because of increasing concentrations of dissolved solids in the groundwater. In 1958, the City of Oceanside began transporting reclaimed sewage to Whalen Lake on the northwest side of the valley, but that practice has since been abandoned. The basin is bounded mostly by marine deposits of Tertiary Age. The groundwater in the surrounding deposits is saline. The San Onofre Breccia borders and underlies the basin on the downstream western edge and is composed of cemented sand, sandy shale and shale that are of low permeability. The rest of the basin is underlain by the La Jolla Group which consist of fine grained, well compacted, and slightly cemented shale. This formation is only slightly permeable. Overlaying the marine deposits is a thick layer of younger alluvium and river channel deposits of clay, silt, sand, and gravel which attains a maximum thickness of 220 feet. Parts of this very permeable area are covered by a layer of fine sand, silt, and clay which confines the groundwater in the underlying aquifer. tii^wi^i iti|ii|jiii - 4 - Seawater intrusion, as well as lateral and upward movement of saline water from older marine deposits, have occurred during periods of low water levels, contributing to the quality problems. Inflow of inferior water from upstream in the San Luis Key River is the primary contributor to inferior quality when water levels are maintained. Due to the gradual degradation of water quality and an overdraft problem in the basin, the City abandoned all attempts to utilize the water when imported sources became available. The City of Oceanside holds basin water rights totalling 18,000 ACFT. The combined pumping of the basin resulted in serious overdraft and increased salt water intrusion. The City of Oceanside reports a well west of the Carlsbad well field, with a total dissolved solid level above 17,000 mg/1. Examination of the wells, pumping equipment, and pipelines making up the well field system reveals that all of these facilities would need extensive repair, if not total reconstruction. Detailed estimates were not made, but it is estimated that a cost of $500,000 to $750,000 would be required for the wells alone. There appears to be no justification to rebuild the transmission system as the water could be "wheeled" through the Oceanside system. - 5 - III. EVALUATION OF WATER RESOURCE POTENTIAL A. LAKE CALAVERA The water production from Lake Calavera appears to be very limited. Water has been released from time to time during periods of high precipitation, but apparently not on a regular basis. The cost involved in putting the limited quantities of water available to beneficial use for domestic purposes are obviously prohibitive. Health Department Regulations require that surface waters be fully treated prior to introduction into the potable water system. The cost to construct facilities to treat the small amount of infrequently occurring water would be much greater than the comparable cost of imported water. A possible use of the impounded surface water, mixed with reclaimed water, might be for irrigation purposes, but examination of that potential proved fruitless as well. The cost of pumping and transmission facilities to deliver the water to the nearest point of use would not be justified for the quantities available. Without the expense of detailed cost estimates and cost benefit analysis, the conclusion may be drawn that Lake Calavera has no potential as a water resource. The Lake and surrounding property - 6 - have value to the City far exceeding any water resource value as discussed under RECOMMENDATIONS below. B. BASIN CONDITIONS The water levels in the Mission Basin have recovered considerably in past years with the reduction (near cessation) of pumping. Quality, however, remains unacceptable for any use. There has been no material change from prior sampling history, based upon recent test results obtained from the City of Oceanside. Maps are attached as exhibits, graphically depicting the water quality. In essence, the quality of water in the basin is not useable without demineralization. The value of the storage potential and the future value of the water when treatment becomes economical, would indicate that the City should preserve it's rights to the water and continue to explore the various alternatives listed in RECOMMENDATIONS below. IV. RECOMMENDATIONS A. LAKE CALAVERA As discussed above, there appears to be no "cost-beneficial" use of the limited water resources represented by Lake Calavera. - 7 - It is recommended that the property be declared surplus and a new appraisal be commissioned preparatory to sale. The last available appraisal was done in 1974 by Robert M. Dodd & Associates and concluded a market value of $1,900,000. In as much as the lands available for residential development proximate to the City proper have been greatly reduced since that time and values have increased dramatically, a new appraisal is in order. Sale of the property surrounding the lake with retention of the "flooded " area for it's limited flood control value (and residential development enhancement) would appear to be in the best interest of the City. San Diego County and possibly other government agencies may have a "right of first refusal" but the City could receive market value for the property. Obviously, the City Council would be free to utilize the sale proceeds as it sees fit, but if the decision was made to retain the funds in the Utilities Department, there would probably be enough to carry out the recommendation regarding the basin and we 11 field. B. WELL FIELD AND BASIN RIGHTS As noted in the above, the existing groundwater quality is unsuitable for potable or even non-potable usage with a TDS of 1800 mg/1. - 8 - One alternative would be for the demineralization of the water as it is pumped from the ground. In the past, it has been generally concurred that demineralization was not an economic alternative as the cost of imported water was much lower than the cost of demineralization. However, the recent price increases for imported water in relationship to the demineralization process, requires another examination of this possibility. In addition to the rising imported water costs, technology has now improved to permit the use of lower pressure membranes for the Reverse Osmosis (RO) process. The current membranes require pressures of approximately 400 to 450 Ibs/sq. inch. Research performed by Water Factory 21 in Orange County now indicates the feasibility of using a low pressure membrane at approximately 250 PSI. Recent technology indicates there is an opportunity for this to go down to 150 PSI - probably in the next 5 years. Capital Costs Appendix 1. is a summary of the capital costs associated with the development of an RO facility to demineralize basin waters to a blend of approximately 500 mg/1, producing 2300 ACPT on an annual basis. Operating Costs The operating costs for such a facility have been based upon actual data prepared by Water Factory 21. (Appendix 2.) The - 9 - results of this analysis have been plotted (Appendix 3.) in comparison with imported water. Several inflation rates were used in an effort to develop a 'window of opportunity1 or at least measure the sensitivity of demineralization versus imported water. For comparison purposes, a value of $50/ACFT was given to the groundwater as the market value of emergency storage. This $50 was deducted from the production costs for demineralized water. Demineralized vs. Imported Water You will note that the feasibility of using demineralized water occurs between 1988 and 1995, depending upon the degree of inflation experienced by either the imported water or the demineralization process. It appears the cost of imported water will experience rather dramatic increases in the next year or two to account for Metropolitan's contract with the State Water Project, as well as the development of the Delta Transfer facility. Taking this into account, Appendix 3 depicts the impact upon imported water versus demineralization should the State assess Metropolitan for these new facilities. This indicates that demineralized local water becomes quite feasible. - 10 - Transfer of Water The analysis also indicates there can be a minimal expenditure of capital funds if the City of Carlsbad can transport their demineralized water to the City of Oceanside and work out a •wheeling' arrangement where water drawn from the well basin can be traded in like quantity in some other part of the Carlsbad system. Thus, eliminating the need of re-constructing any major pipelines for the distribution of water from the well field back to the City's distribution system. Joint Use In addition, it may be desirable to participate in a 'joint' demineralization facility (Carlsbad/Oceanside), as the economies of scale could represent further savings in the development of this natural resource. Advantages The development of local water resources provides 3 advantages. (1) It is an emergency source of water in case of an aqueduct shutdown, (2) it takes advantage of local resources at a potential savings to the ultimate consumer, and (3) it provides storage that is not subject to evaporation problems or surface polution. - 11 - Financial Considerations The foregoing analysis indicates that the demineralization of cbasin waters will, in all probability, become economically feasible within the next 5 to 10 years. This financial feasibility could be further enhanced by participation in Metropolitan Water District's Local Projects program. With greater emphasis being placed upon the development of local resources, much of Metropolitan's focus will be directed to such areas. The technological breakthrough with low pressure membranes provides encouragement for this program. RECOMMENDATIONS Groundwater Enhancement The City of Carlsbad should consider a Joint Development program with the City of Oceanside for the use of the basin waters and the enhancement of a Water Quality program in the tributary area. As Oceanside owns rights to 18,000 ACFT, it obviously has a greater interest and need but would seem to welcome cooperation with Carlsbad. The scope of this study is limited and cannot provide sufficient detail or any firm recommendations regarding the exact method of treatment nor the affiliated costs for a specific method. itmiKlj. 'IB**!*'JB - 12 - Should the City decide to proceed with this project, it is recommended that a careful examination be made of all the demineralization techniques available at this time, such as; electro-dialysis, as well as Reverse Osmosis. There may also be an opportunity to relocate the wells to areas of better water quality, further decreasing the operating cost for the demineralization process and making it possible to sell the more expensive lands located near Mission Avenue. One further recommendation is that the City consider undertaking, jointly with Oceanside, a study of the possibility of a subsurface dam in the Bonsall Narrows area which would stop the migration of poor quality subterranean which is continuing to degrade the basin quality. If the inflow to the basin is surface flow, primarily storm flow, at the same time the poor quality water is being demineralized and removed, there should be a gradual improvement in the water quality. More study and some testing would be required to thoroughly evaluate this approach, but the potential benefits would appear to justify it. A DD ND Glenn U. Reiter & APPENDIX 1. CAPITAL COSTS FOR 1.4 MGD RO PLANT & FACILITIES Item Description 1.4 MGD Reverse Osmosis plant 3 New Wells I Pump Station 1500 GPM (3001) (160HP) 1000' of 12" Pipeline TOTAL Cost $1,000,000 300,000 160,000 30,000 $1,490,000 Assume 20 Year Loan at 10%$175,000 per Year A DD Ciann U—R*it«r * A««ooiota« APPENDIX 2. OPERATING COSTS FOR 1.4 MGD RO PLANT & FACILITIES Energy requirement to demineralize l MG of water - low pressure membrane operating at £50 PSI = 3,500 KWHR. Electrical Energy Cost Chemicals Membrane Replacement 0 & M Sub-total (Note 1) Well Energy 2,300 x 26 = 1,840 ACFT x 308 = (Note 2) Total Divide by 2,300 ACFT = Add Capital Cost Sub-total Less Underground Storage Credit Net Cost of Water 3,500 x $0.13 or S455/MG $148/ACFT $38 $89 $33 $308/ACFT $26/ACFT $59,800 $566,720 $626,520 $272/ACFT $76/ACFT $348/ACFT $50/ACFT $298/ACFT Note: 1.) Assume Product Water Q 175 mg/1. 2.) Treat 1,840 ACFT and blend to get 2,300 ACFT @ 500 mg/1. A DD Glann M. Reitar A ! II il II II ii ii ii ii ii ii ii ii ii 11 ti 11 ii ii ii WATER COST COMPARISON IMPORTED v.s. DEMORALIZED MWO COST/ACFT R.O. COST/ACFT DOLLARS PER ACFT700 600 — 500 4-00 — 300 200 1984 1994 G.M.R. 3/28/84 W.0.8402 • i ii • i ii ii i i i i i i r i 11 ii ii 11 • i 11 ii ii ii ii MWD COST/ACFT WATER COST COMPARISON IMPORTED v.s. DEMORALIZED R.O.O ex COST/ACFT R.O.O BX COST/ACFT 800 DOLLARS PER ACFT 600 400 200 10% INF1ATION 6% INFLATION 1984 1986 1988 1990 1992 1994 YEAR C.M.R. 3/28/84 W.0.8402 1 1 ii ii ii ii it i I i i ii ii ii ii ii ii i i r i MWD COST/ACFT WATER COST COMPARISON IMPORTED v.s. DEMORALIZED R.O. o 6X COST/ACFT R.O. O 8X COST/ACFT 600 DOLLARS PER ACFT 600 400 200 6% INFLATION STATE PROJECT ADJUSTMENT 1964 1966 1986 1990 1992 1994 YEAR G.M.R. 3/28/84 W.0.8402 m t. 2 DATA MCPNESENT LATEST AVAILABLE iNFONMATiON. GENERALLY SUBSEQUENT TO I»t0 ) WHtRE ALINE PATT£MN REPRESENTING A FACTOR >S DASHED, TnE MATING IS DETERMINED IT THAT FACTOR IN ADDITION TO THt tLECTBiCAL CONDUCTANCE 4 SEE APPENDIX D ?0« CHCW<CA DATA BASCO ON SAMPLE OF ONE *CLL COUNTY COUNTY GROUND MATER RATED INFERIOR BECAUSE OF NIDI iECAuSE OF HIGH ^.-i * uRQUND *ATEH RATED iNFERiC* KCAU« OF HIGH ^fffp BORON IN ADDITION TO MiGM EtECTR.CAL CONDUCTANCE RATING OF GROUND WATER FOR IRRIGATION USES OTAL DISSOLVED SOUOS J DATA REPRESENT LATEST MHtAtll INFORMATION, GENERALLY SUBSEQUENT TO I96 OETERWINCD BT THAT FACTOR IN ADDITION TO THE TOTAL DISSOLVED SOLIDS .COUNTY COUNTY «AICO inrmmK MC«U« or HIGH suiraTl GAOUNO w«Trt HVEO MARGINAL BCCAUSC Or HIGH TOTAL DISSOLVED SOLIDS OHND *ar[H BATED W'fRIOI* BECAUSE Or MIGM SuLfATt IN ADDITION TO MIGM TOTAL DISSOLVED SOLIDS CAMP ,DEL MARf / RATING OF GROUND WATER FOR DOMESTIC USES V AI f nr MH. f ^ COUNTY COUNTY 1 NUMBERS REPRESENT PREDOMINANT SUBORDINATE IONS. V' WHERE VARIABLE 2 VALUES REPRESENT LATEST AVAILABLE INFORMATION, GENERALLY SUBSEQUENT TO i960 3 SEC APPENDU Of OR CHEMICAL ANALYSES VALUE BASED ON SAMPLE Of ONE WELL, SUBORDINATE IONS CHEMICAL CHARACTER OF GROUND WATER