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Tools to interpret and implement the Water Quality Standards

We provide resources and guidance to help you understand how the surface water quality standards apply to your work. We provide a general overview about some of our tools; please contact us for technical assistance about specific uses.

The water quality standards provide tools to help users apply the criteria and designated uses to their work. All of these tools can be implemented in various ways and in different water bodies. Please contact us to discuss if any of these tools may be appropriate for your needs. 

Short-term modifications

Short-term modifications allow us to modify the established criteria and special conditions on a short-term basis to accommodate essential activities, respond to emergencies, or to otherwise protect the public interest.

Total Dissolved Gas — Columbia/Snake Rivers


A variance is a change to the water quality standards that is for a limited time and for a specific parameter. A variance may apply to a specific permitted discharger, a group of permitted dischargers, or a body of water.

Other Tools

Mixing Zones
Site-specific criteria
Use attainability analysis
Water quality offsets
Intake credits