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III. NITRATE LOADING STUDY FINDINGS A. GROUNDWATER INFORMATION (SSS§ 4.1, NLS§ 2.0, §2.1, §2.2, and §2.3.) NLS§ 2.1. The 1999 Lines of Equal Depth Map published by the San Joaquin County Flood Control District indicates the static groundwater depth to be approximately 55 ft. The 2020 Lines of Equal Depth Map indicates the groundwater depth to be approximately 80 ft. Both Maps are found in Appendix E. SSS§ 4.2, NLS§ 2.2, 3.1 A 1994 study completed by EHD concerning nitrate impact in domestic wells located in the Morada area, 2.5 miles to the north of the property, revealed that the domestic wells in this area all had comparatively low nitrate concentrations. This is contrary to what would be expected given: 1.) The high density of housing units on septic systems, 2.) The fact that the Morada area was under heavy agricultural production prior to housing development, and 3.) The fact that upgradient agricultural production, along with upgradient commercial facilities remain operational. SSS§ 4.3, 4.4, 4.5, 4.6. There is/are no domestic well(s) on the property and there is no record of any wells ever having been drilled on the property. There is, as referenced on the Tentative Map, an irrigation box in the NWC of the property. Other irrigation appurtenances such as head gates, etc. were not observed. B. SURFACE WATER INFORMATION The rainfall recharge factor used in the Hantzsche-Finnemore equations below has been derived from a water balance document from Norman Hantzsche (one of the authors of the nitrate loading equation) found in Appendix B, which illustrates his water balance analysis of Net Rainfall Recharge (NRR). The data presented in this document indicates an NRR of 8.82" for the Stockton area, and is therefore applicable for this project. C. CALCULATED IMPACT FROM NITRATE -NITROGEN LOADING NLS§ 3.4, 3.5, 3.6. The calculated nitrate -nitrogen impact to the soil and potentially to the groundwater is extremely difficult to determine due to the number of variables involved. For example, the number of people to inhabit the houses and the number of bedrooms per house is unknown and variable. Therefore, the nitrate -nitrogen loading calculated below is based on the proposed acreage and the maximum number of bedrooms each Parcel can support without exceeding the Maximum Contaminant Level (MCL) for each Parcel of 10 ppm nitrate -nitrogen. These calculations mainly pertain to the primary residence, but may be used if an Accessory Dwelling Unit (ADU) is proposed. Additionally, the calculations indicate the number of bedrooms only to approximately 75% of the MCL as a safety factor. -5- Chesney Consulting