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The Problem: 

The Eastern Sierra Community Services District (EDCSD) needed to find cost-effective ways to increase treatment and disposal capacity to support the projected growth at the Bishop Paiute Tribe. Early on, it was discovered that elevated levels of nitrogen were present in the groundwater monitoring wells downgradient of the existing evaporation/percolation ponds and effluent irrigation areas. Therefore, in addition to increasing treatment and disposal of new flows, the study also focused on removing nitrogen from existing flows to reduce groundwater degradation. 

The Solution: 

The preliminary design was completed for various treatment and irrigation options. These options were evaluated in several areas, including cost, reliability, performance, and initial environmental considerations, and the findings were presented to ESCSD. 

The Results: 

Nitrogen can be removed during treatment through careful and proper irrigation or by combining both methods. After discussions with staff at the Lahontan Regional Water Quality Control Board (LRWQCB) about this project, it was found that antidegradation water quality standards in Owens Valley would be enforced. This means the new discharge would not cause groundwater quality to drop below the existing background levels of 1 to 2 mg/L total nitrogen. Historically, LRWQCB only enforced beneficial use standards (less than 10 mg/L total nitrogen) and did not apply stricter antidegradation standards. To permit total nitrogen levels above current conditions, the LRWQCB issued findings supporting the allowance of higher levels. These findings justified limited groundwater degradation based on factors such as technical feasibility, cost, and public benefit.