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5.2 Description of impact of rainfall contribution of nitrate load to the project site: The impact of rainfall contribution on the project site was completed to determine the nitrate load. The average monthly precipitation and evapotranspiration are required to calculate the site nitrate load. These two values are used to estimate the deep percolation. The annual rainfall recharge is estimated by analyzing the difference between the monthly average precipitation and the evapotranspiration when the precipitation exceeds the monthly average evapotranspiration. These calculations are attached in the Appendix. The data for the potential evapotranspiration water was obtained from the California Irrigation Management Information System (CIMIS). The project is located within an area designated as Zone 12. Based on the values for this area along with the average monthly precipitation values obtained from the Western regional Climate Center for the region an estimate of the deep percolation of rain for the project was determined. Station 262 in Linden had the most similar weather and soil conditions to our project site. The results for the average rainfall recharge at the site were ) 7.5 in./year. The nitrate concentration is estimated to be about 1 mg/L-N. (Hantzche and Finnemore, 1992). 5.3 Description of all current on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The only source of nitrates are the existing septic systems in use by the existing residences. The existing septic systems were considered for when determining the approximate nitrate concentration, the site could expect with the proposed development. 5.4 Discussion of all proposed future on-site sources of nitrate to soil and groundwater and the contribution of nitrate load from these sources to the project site: The existing use for this site is agricultural and residential. The future use of the Homesite Parcel will be residential, Parcels 2 and 3 will be used for agricultural and residential purposes, and Parcel 1 will be used for agricultural purposes. It is expected that each residence will generate 100 gal/day of waste for the first bedroom and 50 gal/day for every subsequent bedroom. Parcel 1 currently does not have any residences on it. Assume one new 3 bedroom permanent residence and one 2 bedroom permanent additional dwelling unit is constructed. This would generate 350 gal/day of waste on Parcel 1. Parcel 2 has one 2 bedroom manufactured on it. Assume the manufactured home is removed and a new 3 bedroom permanent residence and a new 2 bedroom permanent additional dwelling unit is constructed. This would create 350 gal/day on Parcel 2 which would exceed the existing waste load of 150 gal/day. Parcel 3 currently has one 2 bedroom permanent residence, and one 1 bedroom manufactured additional dwelling unit. Assume the manufactured secondary residence is removed and a new 2 bedroom permanent secondary dwelling unit is constructed. This would generate 300 gal/day on Parcel 3 which would exceed the existing waste load of 250 gal/day. The Homesite Parcel currently has one 4 bedroom primary residence and one 3 bedroom additional dwelling unit which generate a total of 450 gal/day of waste on the homesite parcel. The project site would generate a total of 1)A gal/day which can ne sustained as shown in the attached calculations. 1460 The average total nitrogen concentration of domestic wastewater is about 20-85 mg/L-N, although 35-45 mg/L-N is a better approximation (Crites and Tchnobanglous). The value selected for this site was 45 mg/L-N. 3