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Ecoregional Criteria
Ecoregion I: Willamette and Central Valleys
This document presents EPA's nutrient criteria for Nutrient Ecoregion I. These criteria provide EPA's recommendations to States and authorized Tribes for use in establishing their water quality standards consistent with section 303(c) of the Clean Water Act (CWA). Under section 303(c) of the CWA, States and authorized Tribes have the primary responsibility for adopting water quality standards as part of State or Tribal law or regulation.
The ecoregion is defined as: Willamette and Central Valleys, including all or parts of the states of Washington, Oregon, and California, and the authorized Tribes within the ecoregion.
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- Ecoregional Criteria Document for Lakes & Reservoirs: (Under development)
- Ecoregional Criteria Document for Rivers & Streams (PDF) (EPA 822-B-01-012; 2.7MB)
- From the Nutrients Database: Aggregate Ecoregional Nutrient Criteria