Cal. Code Regs. tit. 23 § 3939.1
The amendment revises the Basin Plan by updating the ammonia water quality objectives for inland surface waters. The Basin Plan objectives for ammonia are based on revised criteria developed by the U.S. Environmental Protection Agency (USEPA) in the "1999 Update of Ambient Water Quality Criteria for Ammonia." These most recent USEPA freshwater aquatic life criteria for ammonia supercede previous criteria. The previous Basin Plan one-hour average and four-day average objectives for waters designated as "WARM" are retained for waters not characteristic of freshwater.
The ammonia objectives provide 1-hour average, 4-day average, and 30-day average objectives for ammonia. The one-hour average objective is dependent on pH and fish species (salmonids present or absent). It is assumed that salmonids may be present in waters designated in the Basin Plan as "COLD" or "MIGR" and that salmonids are absent in waters not designated in the Basin Plan as "COLD" or "MIGR," in the absence of additional information to the contrary. The 30-day average objective is dependent on pH and temperature. At lower temperatures, the 30-day average objective also is dependent on the presence or absence of early life stages of fish (ELS). Water bodies with a Basin Plan designation of "SPWN" support high quality aquatic habitats suitable for reproduction and early development of fish and, therefore, these water bodies are designated as ELS present waters. The four-day average objective is 2.5 times the 30-day average objective.
The Basin Plan amendment also includes specific implementation provisions for the objectives. These include methods for (1) determination of freshwater, brackish water or salt water conditions; (2) determination of presence or absence of salmonids when selecting the appropriate one-hour average objective; (3) determination of presence or absence of ELS when selecting the appropriate 30-day average objective; (4) implementation of the objectives where more sensitive threatened or endangered species are present; and (5) translation of objectives to effluent limitations using a method similar to that in the "Policy for Implementation of Toxics Standards for Inland Surface Waters, Enclosed Bays, and Estuaries of California" (2000).
Cal. Code Regs. Tit. 23, § 3939.1