SU0003307 - Laserfiche WebLink

Home Browse Search

TABLE 3 WATER QUALITY PARAMETERS FOR WELLS AT 90 FEET AND 200 FEET BORING DEPTHS Nitrate (mg/L) (as N0,) Conductivity (umhos/cm) Monitoring wells Domestic wells Monitoring wells Domestic wells Year at 90 ft at 200 ft at 90 ft at 200 ft 1985 69 7.9 1,070 353 1986 89 6. 1,010 326 1987 74 15.5 1 , 100 67 1988 71 8.8 1,060 479 C. Nitrogen Loading Nitrate levels in percolating water will be much higher at relatively shallow depths (90 ft) than at depths for domestic wells (200 ft) near QAP. Based on calculations for a nitrogen balance, farming operations such as crop ferti - lizing, not application of wastewater from QAP, are the likely cause of elevated nitrate levels. These conclusions are based in part on data for Total Kjeldahl Nitrogen and nitrate levels in QAP facility effluent, Table 1 , and annual wastewater applications of 220 million gallons to 246 acres of land under agricultural cultivation. A summary of the nitrogen balance is presented in Table 4. D. Summary of Water Quality Impacts`6' Existing shallow groundwater in the vicinity of QAP has moderately elevated nitrate and salinity levels as a result of decades of irrigated agriculture. Locally the shallow groundwater salinity will be only slightly affected by QAP wastewater disposal operations. As the combined flow of percolate and ground- water move down gradient further dilution will occur. It appears that the aquifer in the Laguna formation tapped by most domestic wells is sufficiently isolated from the shallow groundwater to maintain its relatively high quality. This isolation is maintained locally by a stratum of low hydraulic conduc- tivity which exists in the region between 50 and 150 ft below ground surface. .-- Therefore, QAP wastewater disposal operations should have no significant effect on the quality of water from domestic wells in the area. 7 RP050-L