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Impact to Underlying Groundwater and Downgradient Wells In all considerations to the groundwater, the conclusion from the soil digs demonstrate that the soil profile has layers of clay that have varying percentages of clay content, all being high, which will slow the penetration from surface water percolation down to the water table. This slowing of the percolation allows for a greater impact of drying periods. This dairy system will have a water storage volume that has a capacity greater than the requirements from both the county and state. The minimum required storage is 180 days. The calculated capacity for the existing system is: Nutrient Lagoon- 17,092,447 gallons Existing Settling Pond- 2,674,226 gallons Existing Settling Pond- 267,008 gallons Existing Settling Pond 1,118,921 gallons Future Settling Pond 2,674,226 gallons Total Storage 23,826,828 gallons These capacities will allow for containment of a full winter's manure volume, an above average winter rainfall plus a 25 year, 24 hour storm water volume. Considering these storage volumes, the manure effluent management system can be managed by plan, not managed by rainfall events. Well managed irrigation and return water flows, along with wet-dry cycles, will cause surface water not to penetrate the approximate 10-18 feet of the depth to static water table'. In order to evaluate future water quality, water wells in the area were tested to establish a baseline of various elements. (Reference appendix IIII for test results). A water sample was taken from one of the four domestic wells at the Lima Dairy milling facility. A water sample was taken from the domestic well at the Lima heifer facility. A water sample was taken from a domestic well at 4484 West Tredway Road. A water sample was taken from a domestic well at 13151 Neeley Road. A water sample was taken from a domestic well at 5882 West Kingdon Road. Water samples from these five wells were analyzed by A&L Western Agricultural Laboratories in Modesto. The samples were tested for nitrate, using EPA method 353.2, and tested for TDS. using EPA method 160.1. The results show that nitrates are present in all of the samples. The presence of nitrate in the ground water indicates that there may be some agricultural contribution. Furthermore, the consistent level of nitrate in the ground water indicates that the nitrate in these waters is more a result of a regional infiltration into the water table, rather than contribution from a localized source. gional infiltration into the water table from the There may be factors contributing to the re surrounding area, and described as follows: White Slough Waste Water Treatment facility has an operating facility with monitoring wells in and around the dairy facility. Based on the data provided by City of Lodi, from 1989 to 1993 there was a gradual increase in nitrate levels of monitoring wells 1 through 5, and in one well exceeding the limit of 45 ppm. Between 1994 and 1995, well number 5 went from 41 ppm to 136 ppm of nitrates, increasing gradually within four quarterly monitoring events (this well is directly southwest of the dairy facility less than one mile), and gradually decreased to under 45 ppm in 1996. Also in 1994, two additional wells were added number 6 and number 7, which are south of the dairy, downgradient from the number 5 well. Number 7 well had an average limit of 31 in 13 quarters, less than 45 ppm. In 2001, nine additional wells were added 8 through 16, all located south and southwest of the dairy facility, showing no nitrates or other abnormal results from the two monitoring events. It was the understanding that the addition of these wells were due to the shift of flow in ground water from northwest to the southeast. 18 ®Western Design/David Avila 2001