View File - Development Services - City of Oxnard

WATER RESOURCES TECHNICAL REPORT• Small decline in groundwater elevations in the immediate vicinity of the City WaterYard in the UAS and LAS as a result of extracting 2,251 AFY (80 percent) of the2,814 AFY of in-lieu recharge from the four City Water Yard wells: two LAS wells(Nos. 20 and 21) and two UAS wells (Nos. 22 and 23). Water levels decreased up to 3 feetin the UAS and up to 6 feet in the LAS. These water level decreases will result in thefollowing:−−In the UAS, these small decreases will not significantly affect the low potential forcoastal landward flow, even during extended, drier climatic periods (see Scenario 1ahydrograph for coastal well 05G02, which remains above sea level for the simulationperiod [Figure 6-16]).In the LAS, these small decreases will incrementally increase the moderate potentialfor landward flow that exists, particularly during drier years and in the fall whenwater levels are seasonally low.• Imperceptible decline in groundwater elevations in the Forebay area as a result ofextracting 563 AFY (20 percent) of the 2,814 AFY of in-lieu recharge from the El Riowellfield.These changes will result in the following reductions in overdraft:• For the UAS, the average height above the coastal water level goal will remainapproximately the same, 5.8 feet for Scenario 1a compared to 5.7 feet for the Base Case.• For the LAS, the reduction in overdraft will be 4 percent compared to the Base Case.Scenario 1bScenario 1b results in the following changes relative to the Base Case:• Virtually the same small rise in groundwater elevations across the southern OxnardPlain and Pleasant Valley areas as for Scenario 1a (the in-lieu recharge assumptions arethe same for Scenarios 1a and 1b).• Almost imperceptible decline in groundwater elevations in the immediate vicinity of theCity Water Yard in the UAS and LAS as a result of extracting 563 AFY (20 percent) of the2,814 AFY of in-lieu recharge from the two City UAS wells (Nos. 22 and 23).• Small decline in groundwater elevations in the Forebay area as a result of extracting2,251 AFY (80 percent) of the 2,814 AFY of in-lieu recharge from the UWCD El Riowellfield. Water levels decreased up to 5 feet in the UAS and up to 2 feet in the LAS.These water level decreases will result in the following:−−In the UAS, these small declines will not interfere with pumping operations at theForebay spreading grounds or significantly affect the low potential for coastallandward flow at the coast (see Scenario 1b hydrograph for coastal well 05G02,which remains above sea level for simulation period [Figure 6-16]).In the LAS, these small declines will not significantly increase the moderate potentialfor landward flow that exists.W112003002SCO LW1458.DOC/ 033390002 87