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D. GROUNDWATER INFORMATION Groundwater elevations are illustrated on maps published by the San Joaquin County Flood Control and Water Conservation District. The 1998 Lines of Equal Depth map denote the water table depth at approximately 70 feet below grade. The 1998 Lines of Equal Elevation indicateIII the groundwater elevation to be approximately-40 ft below mean sea level. The groundwater under the subject property may be influenced by the Little Johns Creek, adjacent to the north property border, and Highway 99. The static water level was measured within the on-site domestic well at 69 ft below the wellhead. This correlates with the Lines of Equal Depth map. As with all groundwater tables,there will be fluctuations in elevation. The 1992 Lines of Equal Elevation map indicates the groundwater table to be at-50 ft. Therefore,the water table has risen 10 ft in the last eight yrs. The critical issue regarding the groundwater elevation under the subject property is that there is sufficient distance between the floor of the 25-ft seepage pits and the highest anticipated depth to groundwater for sufficient wastewater treatment to occur. The groundwater directional flow appears to be in an easterly direction toward a zone of recharge. The water table elevation declination is relatively gradual toward this zone of recharge. The directional flow of the groundwater should be assumed to be approximate since there are many influences on flow, particularly from the Little Johns Creek. To determine the extent of nitrate impact to the underlying drinking water aquifers, a water sample was taken from the on-site domestic well for nitrate and DBCP/EDB analyses. This well is theoretically upgradient from the existing septic tank and will be theoretically crossgradient from the future leachfield and seepage pits. Test results indicate a nitrate (as NOD concentration of 7 ppm. The Maximum Contaminant Level (MCL) for nitrate (NO3) in drinking water is 45 ppm. Therefore,the nitrate impact to upgradient and underlying aquifers has been minimal. This 7 ppm concentration may be indicative of background, or naturally occurring nitrate. DBCP/EDB concentrations were Below Detection Limits (BDL), or Non-Detect (ND). E. SURFACE WATER INFORMATION Surface water impoundments for the proposed project will include a drainage/evaporation pond. This pond will be located downgradient from the leachfield and may contribute a slight dilution effect to the effluent in the top aquifer mixing layer. The Little Johns Creek is theoretically crossgradient from the leachfield area. Influence from this Creek to the leachfield area is unpredictable. 4 Va&y sig Research