View File - Development Services - City of Oxnard

WATER RESOURCES TECHNICAL REPORTto the GREAT Program facilities, and UWCD facilities will be used to help distributerecycled water to agricultural customers on the Oxnard Plain. The UWCD service boundaryand major recharge and conveyance facilities are shown in Figure 2-3. A summary of thesefacilities and their operations is provided below, from upstream to downstream.Santa Felicia DamSanta Felicia Dam (1955) captures and stores winter runoff from Piru Creek for later releasein controlled amounts to replenish the Piru, Fillmore, Santa Paula, and Oxnard Plaingroundwater basins, and supply surface water for irrigation. The watershed above the damis approximately 432 square miles, mostly in Los Padres National Forest. Upstream of thedam on Piru Creek is Pyramid Lake, owned by DWR. The alignment of the dams allowsUWCD to receive imported State Water Project water via release down Piru Creek, withoutthe expense of constructing conveyance facilities.Freeman DiversionThe Freeman Diversion (1991), located near Saticoy, diverts water releases from Lake Piruand natural runoff from the Santa Clara River and its main tributaries (Sespe, Santa Paula,and Hooper Creeks) for artificial groundwater recharge and agricultural irrigation. Annualyield from the Santa Clara River increased substantially with construction of the FreemanDiversion, which replaced temporary diversion dikes with a permanent concrete structure.Winter storm flows of up to 375 cfs, the permitted amount, are diverted to spreadinggrounds on the Oxnard Plain Forebay for groundwater recharge and provided to growerson the southern Oxnard Plain and Pleasant Valley to offset groundwater pumping. Thediversion amounts are much lower during dry years and dry months of average years whenthere is typically little flow. The annual flow in the Santa Clara River was 50,400 AFY atMontalvo (below the Freeman Diversion), and the Freeman Diversion captured anadditional 57,700 AFY of flow for recharge and irrigation during the 2000 water year, whichhad precipitation approximately 90 percent of normal.Figure 3-3 shows historical UWCD diversions, and Figure 3-4 shows historical water qualityof the Santa Clara River at the Freeman Diversion. In general, the water quality of dissolvedconstituents shows an inverse correlation with flow in the river, with higher concentrationsassociated with lower flows. TDS of the surface water generally ranges from 500 to1,500 mg/L, consistent with water quality across the Oxnard Plain that is not degraded, asdescribed in Section 2.0.Water is not diverted from the Santa Clara River during and immediately followingsignificant rainfall because of the high river sediment load. Water diverted from the riverflows via canal and pipeline to the 44 acre desilting basin, where water velocity slows,allowing sediment to settle out of the water column. From the desilting basin, water flowsvia pipe and canal to the Saticoy spreading grounds. From the main canal at the Saticoyspreading grounds, water can be directed to either percolation ponds or to the main supplypipeline. The main supply line transports water to the El Rio spreading grounds and thePleasant Valley County Water District and the PTP agricultural water delivery systems.Existing Groundwater Recharge FacilitiesUWCD began a systematic program of groundwater recharge in 1928, primarily throughdiverting surface water using sand dikes into spreading grounds along the Santa ClaraW112003002SCO LW1458.DOC/ 033390002 30