Section 58.01.02.051 - ANTIDEGRADATION POLICY01.Maintenance of Existing Uses for All Waters (Tier I Protection). The existing in stream water uses and the level of water quality necessary to protect the existing uses shall be maintained and protected.02.High Quality Waters (Tier II Protection). Where the quality of the waters exceeds levels necessary to support propagation of fish, shellfish and wildlife and recreation in and on the water, that quality shall be maintained and protected unless the Department finds, after full satisfaction of the intergovernmental coordination and public participation provisions of the Department's continuing planning process, that allowing lower water quality is necessary to accommodate important economic or social development in the area in which the waters are located. In allowing such degradation or lower water quality, the Department shall assure water quality adequate to protect existing uses fully. Further, the Department shall assure that there shall be achieved the highest statutory and regulatory requirements for all new and existing point sources and cost-effective and reasonable best management practices for nonpoint source control. In providing such assurance, the Department may enter together into an agreement with other state of Idaho or federal agencies in accordance with Sections 67-2326 through 67-2333, Idaho Code.03.Outstanding Resource Waters (Tier III Protection). Where an outstanding resource water has been designated by the legislature, that water quality shall be maintained and protected from the impacts of point and nonpoint source activities.04.Thermal Discharges. In those cases where potential water quality impairment associated with a thermal discharge is involved, antidegradation shall be implemented consistent with Section 316 of the Clean Water Act.05.Waters Subject to the Antidegradation Policy. Idaho's antidegradation policy only applies to waters subject to the jurisdiction of the Clean Water Act.Idaho Admin. Code r. 58.01.02.051