Water Quality

Use Attainability Analyses and Site Specific Criteria are used to ensure that designated uses or criteria are appropriate for a given waterbody. If a state is removing a designated aquatic life or recreational (“fishable, swimmable") designated use from a waterbody, or adding designated uses to a waterbody that do not include aquatic life or recreational uses, it must develop a use attainability analysis. This is a structured scientific assessment of the factors affecting the attainment of aquatic life and recreational uses. The factors to be considered include physical, chemical, biological and economic factors, which are described in federal regulations found at 40 CFR 131.10(g)(1)-(6). If a state finds that a designated use is not attainable through a UAA, it must adopt the highest attainable use, which is the modified aquatic life, wildlife or recreation use, and associated criteria, that are closest to the use that is being removed and is attainable, based on the findings of the use attainability analysis.

Oregon water quality standards include provisions for developing site-specific criteria for water quality standards for temperature (see OAR 340-041-0028(13) ) and toxic substances (see OAR 340-041-0033(5)). Any adoption of site-specific criteria must also be consistent with federal provisions at 40 CFR 131.10.

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Water Quality Standards Revision for West Di​vision Main Canal Near Hermiston, Oregon​ 

The Oregon Environmental Quality Commission adopted new water quality standards for the West Division Main Canal near Hermiston, in northeastern Oregon, at their meeting on Apr. 26, 2012. The rule corrects previous standards, establishing designated beneficial uses and associated water quality criteria that are appropriate for and feasibly attainable in the canal.

On Friday, Nov. 15, 2013, EPA partially approved and partially disapproved the revised standards for Canal. Only the standards changes approved by EPA are effective.

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