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7UJOUu—.)J`e .V1 —. v 4.3.2.3 Agricultural Use 4.3.2.3.1 As discussed by Hotchkiss and Balding (1971) three of the most important factors pertinent to irrigation water quality in the Tracy- Dos Palos area are: • Concentration of boron • Salinity hazard • Alkalinity hazard 4.3.2.3.2 To evaluate the feasibility of using water in the Upper Tulare HSU for agricultural purposes, water samples from three wells located northeast of the Depot were sampled in January 1989 and analyzed for selected inorganic water quality parameters (WCC 1989) . The three wells, LM 72, LM 60, and LM 56, are completed in successively deeper zones with screened depths of 21.5 to 31.5, 80 to 100 and 120 to 140 feet BGS, respectively. Well LM 72 is screened in the Upper Horizon, Well LM 60 is screened in a predominantly sand-sequence at the elevation of the Middle Horizon, and Well LM 56 is screened in the Lower Horizon. The results of the chemical analyses from these three wells are shown in Table 4.3-2, and the well locations are shown on Figure 2.6-2. 4.3.2.3.3 The boron concentrations from the three wells ranged between 1.1 to 1.8 mg/l (Table 4.3-2) . These values exceed the 0.75 mg/l criterion for long-term irrigation on sensitive crops (EPA 1976) which includes walnuts grown in some off-Depot areas. As such, the groundwater in this area may not be suitable to use for long-term (continuous) irrigation for agricultural products sensitive to boron. 4.3.2.3.4 The specific conductance has been measured at 1000 micromhos/cm (umhos/cm) for LM 56,. 1300 umhos/cm for LM 60, and 1500 umhos/cm for LM 72. Of the three wells sampled, the deepest groundwater well , LM 56, had the lowest specific conductance value; however, all three values are considered to be within a "high" salinity hazard category, which may require special management for salinity control and/or cultivation of plants with good salt-tolerance. 4-163