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<br />· aEPA <br /> <br />. <br /> <br />. <br /> <br />Fact Sheet <br /> <br />Antidegradation Policy - 40 CFR 131.12 <br /> <br />The antidegradation policies of States and Tribes ensure that water quality is conserved where <br />possible and lowered only when necessary, and that people who may be affected by the lowering <br />of water quality have a say in the final decision. EP A regulations at 40 CFR 131.12 require <br />States and authorized Tribes to adopt an anti degradation policy that conforms to the Federal <br />regulation and to identify implementation procedures. <br /> <br />The anti degradation policy is one of the three main elements of States' and Tribes' water quality <br />standards. Designated uses establish the water quality goals for the water body, water quality <br />criteria define the minimum conditions necessary to achieve the goals and the antidegradation <br />policy specifies the framework to be used in making decisions about changes in water quality. <br />Antidegradation was originally based on the spirit, intent, and goals of the Act, especially the <br />clause "...restore and maintain the chemical, physical and biological integrity of the Nation's <br />waters" and explicitly required by the 1987 amendment codified in section 303(d)(4)(B) <br />requiring satisfaction of antidegradation requirements before making certain changes in NPDES <br />permits. Antidegradation plays a critical role in allowing States and Tribes to maintain and <br />protect the finite public resource of clean water and ensure that decisions to allow reductions in <br />water quality are made in a public manner and serve the public good. The water quality <br />standards regulation has established three tiers of protection: <br /> <br />. <br /> <br />Tier I (40 CFR 121.12(a)(1)), protects existing uses, provides the absolute floor of water <br />quality in all waters of the United States and applies a minimum level of protection to all <br />waters. <br /> <br />. <br /> <br />Tier II (40 CFR 121.12(a)(2)), protects high quality waters, applies to waters whose <br />quality exceeds that necessary to protect the section 101(a)(2) goals of the Act. Tier II <br />ensures that where water quality is better than the minimum level necessary to support <br />protection and propagation of fish, shellfish and wildlife, and recreation in and on the <br />water ("fishable/swimmable"), that water quality is also maintained and protected unless, <br />through a public process, some lowering of water quality is deemed to be necessary to <br />allow important economic or social development to occur. <br /> <br />. <br /> <br />Tier III (40 CFR 121.12(a)(3)) applies to water bodies of designated exceptional <br />recreational or ecological significance, commonly termed Outstanding National Resource <br />Waters (ONRWs) where the ordinary use classification and supporting criteria may not be <br />sufficient or appropriate to identify and maintain and protect water quality in such water <br />bodies. As described in the preamble to the Water Quality Standards Regulation, "States <br />may allow some limited activities which result in temporary and short-term changes in <br />