Site-Specific Objectives/
Anti-Degradation Analysis
Anti-Degradation Analysis
The purpose of this study is to use the protective thresholds determined from the agricultural, endangered species chloride threshold studies, as well as information from the groundwater-surface water interaction study and any other relevant information, to develop a site-specific objective (SSO) for chloride (if necessary) for the relevant areas in the study area as specified in the settlement agreement. The combination of these studies and other technical analyses are the foundation upon which the Regional Board may base a Basin Plan Amendment for chloride.
The study will also ascertain whether an anti-degradation analysis (ADA) is required, and then prepare an ADA, if necessary. An ADA is required by both Federal (Clean Water Act) and State (Porter-Cologne Act) regulations, if a Basin Plan Amendment is pursued to revise an existing water quality objective to meet a less stringent water quality standard. Federal anti-degradation regulations establish a three-part test that applies to activities that lower water quality. The first tier requires that in-stream water uses be protected and maintained. The second tier applies where the water quality standard is higher (better) than necessary to protect in-stream uses. Under this tier, the state can allow a lowering of water quality standards, provided that in-stream uses are protected and that the state finds that the lowering of a water quality standard “is necessary to accommodate important economic or social development” in the area. The third tier applies to outstanding national resource waters. The purpose of the SSO/ADA study is to provide the technical and policy information necessary for the Regional Board to use to determine if a Basin Plan Amendment for chloride is needed.
Study Process
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