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Case Studies: Setting Ecologically-based Water Quality Goals

Historically, water quality programs have relied upon performance-based standards to establish allowable pollutant loads, monitoring requirements, and enforcement actions. Performance-based standards focus on individual pollutants and are used to regulate specific activities. The use of impact standards or outcome indicators -- requiring that a certain result be achieved -- serves a complementary function that provides flexibility, realism, and a direct measure of ecological integrity.  It is of critical importance that impact standards be specific, well defined, and allow for waters of different natural quality and different desired uses.  Both Maine and Ohio have recognized this problem and have developed tiered systems of aquatic life use designations, which make use of biological information to develop graduated levels of protection.