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4.) The wastewater system consists of a mechanical separator, a holding pond and a smaller separation pond. A percentage of the nitrogen entering this system will volatilize as ammonia or be adsorbed onto the clay soil particles lining the ponds. Ammonia volatilization occurs from urine, manure wastewater transfer to the ponds, and during pond storage. Both ponds were hydrometer tested for clay content in August 1995 according to Regional Water Quality Control Board requirements. Clay content in both ponds was determined to be over 42%; consequently, there is adequate clay to "bind" a high percentage of ammonium molecules and thus prevent the conversion to nitrate. The ponds can also be considered anaerobic. An aerobic environment is required for nitrate molecule formation. This can only take place if the ponds were allowed to dry out. When the manure in the ponds is eventually cleaned-out or draglined, it is important that it be done when possible after the water is pumped down to prevent this conversion from taking place. An investigation by Sutton, et al. (1983) suggest that a nitrogen loss from a lagoon or pond liquid system can range from 70% to 80%. The second issue regarding the ponds is the natural process of denitrification. As referenced, this process takes place only in anaerobic environments.such as saturated clay soils where the pore space volume is extremely small. This accounts for 15% to 20% nitrogen loss. It has been our experience nitrate concentrations in groundwater around wastewater holding ponds is comparatively low in high clay content soils. 5.) Upon separation of the wastewater from manure solids by using a mechanical separator, the solids are stockpiled on a concrete slab. However, there is manure overflow onto the soil in this area. The manure stacked on the soil can create a "point-source" of nitrate conversion and infiltration into the underlying soil. Fortunately, the manure turnover in this area is rapid so there may not be enough time for conversion to take place. The total nitrogen excreted from the animals has been historically difficult to quantify since the rates of several important nitrogen transformation processes (e.g., ammonia volatilization and denitrification) are unknown. The following calculations incorporate the use of animal units to formulate the waste loading. Animal numbers are approximate and represent values toward the upper range: Milk Cows . . . . . . . . . . . . .2500 (2500 X 1) Dry Cows and Heifers . . . 450 (600 X 0.75) Calves . . . . . . . . . . . . . . . . 120 (300 X 4) TOTAL Animal Units . . . 3070 A.U. 7