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NORMAN E. PEHRSON Now, I will briefly describe how we integrate the operation of our flood control reservoirs with water spreading. We believe the proper reservoir operation for flood control can and does pro- vide opportunities to improve spreading and subsequent ground water recharge. Ground water re- charge is enhanced to the extent that floodwaters are reduced in peak and discharged over an ex- tended period of time. Ground water recharge is enhanced' by the seepage that is inherent in reservoir pools. . In the LACDA project, we operate five reservoirs, as I mentioned before, in close coordination with the Los Angeles County Flood Control District. We restrict releases, when possible, to the down- stream recharge capacity of the spreading facilities. Typical of the spreading grounds used in this op- eration are those downstream from Hansen Reservoir, which encompass an area of about 200 acres. Also typical of the spreading grounds used in this operation are those downstream from Whittier Nar- rows Reservoir, which cover an area of about 600 acres. At Santa Fe Reservoir, a substantial part of the reservoir area itself is reserved for operation of ground water recharge basins. Surface flows en- tering the reservoir are diverted from the San Gabriel River and into extensive spreading grounds. When the San Gabriel River Freeway is extended through'the Santa Fe Reservoir, part of the spread- ing grounds will be displaced by freeway fill. Therefore, plans are being made to extend the spread- ing grounds into the spillway channel downstream from the dam. In the Santa Ana River Basin and Orange County project, we also operate our reservoirs to in- sure maximum utilization of floodwaters. For example, operation of San Antonio Reservoir is coor- dinated with spreading activities conducted by local water agencies. Construction of San Antonio Dam involved the restoration of surface water diversion facilitie~ to preserve the ground water supply of the Pomona Valley Protective Association as well as San Bernardino County, and also involved the reloc- ation of underground water-collection galleries and outlets - constructed before the turn of the cen- tury and still in operation - to preserve the ground water supply of the San Antonio Water Company. Our borrow excavation in the reservoir area was so performed as not to reduce the supply to the col- lection system. At Prado Reservoir, we coordinate operation of the reservoir with the spreading oper- ations of the Orange County Flood Control District in the Santa Ana River. Our operation of two other projects should be of!interest to you: Whitlow Ranch Reservoir, on Queen Creek in Arizona, has an ungated outlet designed to reduce our standard project flood to a discharge that can be absorbed in the downstream ground water basins. Mojave River Reservoir, which is now under construction in California, will also have In ungated outlet so designed as to reduce floodflows to a discharge that will permit their complete percolation into the downstream ground wat- er basins. ~ Thus far, I have confined my discussion to the c(!nservation of floodwaters, local runoff, and imported water. However, we also recognize another imRortant source to enhance and augment the ground water supply, and that is waste-water reclamation. Although the Corps has not been directly involved in such effort, we have made our reservoir lands available for waste-water reclamation by local sanitation districts. Probably the best known is the pilot plant operated by the Los Angeles County Sanitation District at Whittier Narrows Reservoir, where more than 16,000 acre-feet were reclaaned for ground water recharge in the water year 1966-67. Another plant is now in the design stage for construction at Sepulveda Reservoir by the City of Los Angeles Department of Water and Power. Current plans indicate that the plant will be in 'operation about 1970. The City of Chino, which operates a plant in Prado Reservoir, reclaimed 1,730 acre-feet for ground water recharge in the water year 1966-67, and the City of Corona has started ~onstruction of another reclamation plant in the same reservoir. The effluents from these plants will qontribute a significant input to the ground water supply. I would like to point out that the City of L6s Angeles is planning nine more plants to be completed in the next 20 years. Also of interest is the, plan being considered by the Los Angeles County Flood Control District to reclaim waste water no* being discharged by the Hyperion plant in- to the ocean. The reclaimed water would be used for hydraulic barriers to prevent salt water intrusion in the Manhattan Beach area. ' v -12-