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Water: Ecoregions

Ecoregional Criteria Ecoregion III: Xeric West

This document presents EPA's nutrient criteria for Nutrient Ecoregion III. 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: Xeric West, including all or parts of the states of Washington, Oregon, California, Nevada, Idaho, Wyoming, Montana, Utah, Colorado, New Mexico, Arizona, Texas and the authorized Tribes within the ecoregion.

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