Idaho Code § 39-3607
The director shall, in consultation with the appropriate basin advisory group and watershed advisory group, conduct a beneficial use attainability assessment to determine whether beneficial uses should be revised. Designated uses shall be reviewed and revised when such physical, geological, hydrological, atmospheric, chemical or biological measures indicate the need to do so. The director shall consider the economic costs required to attain a revised beneficial use. A designated use, that is not an existing use, shall be removed when it is demonstrated that attaining the use is not feasible, using those factors set forth in 40 CFR 131.10(g).
Previous assessments of beneficial use attainability that are of a quality and content acceptable to the director shall constitute the baseline data against which future assessments shall be made to determine changes in the water body and what beneficial uses can be attained in it. In addition, the director, to the extent possible, may determine whether changes in the condition of the water body are the result of past or ongoing point or nonpoint source activities. The director shall also seek information from appropriate public agencies regarding land uses, water uses and geological or other information for the watershed that may affect water quality and the ability of the water body in question to attain designated beneficial uses. In carrying out the provisions of this section, the director may contract with private enterprises or public agencies to provide the desired data.
Idaho Code § 39-3607