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Water Quality Standards for Toxic Pollutants

Water quality standards are the foundation of the water quality-based control program mandated by the Clean Water Act. Water Quality Standards define the goals for surface waters in Oregon by designating its uses, setting criteria to protect those uses and establishing provisions to protect water quality from pollutants.

DEQ is responsible for establishing water quality criteria for toxic pollutants to protect both aquatic life and human health. These criteria are established to protect surface water for aquatic life use and to allow Oregonians to consume fish and shellfish and to use state waters for drinking water supply without adverse health effects. DEQ develops its water quality criteria based on EPA recommended criteria. 

Current Toxics Standards

Human Health and Aquatic Life Criteria Tables

Table Description
Human Health Criteria
Table 40 Effective human health criteria
Aquatic Life Criteria
Table 30 Effective aquatic life criteria
Table 31 Guidance values ONLY
Tables 30, 31, and 40

NOTE: On Jan. 7, 2015, the Oregon Environmental Quality Commission adopted revised freshwater criteria for ammonia. These criteria will not be in effect until EPA approval. See Revised Table 30 for adopted ammonia criteria.

Toxics Standards Rule (OAR 340-041-0033)

Human Health Toxics Criteria

On Oct. 17, 2011, EPA approved revisions to Oregon’s criteria to protect human health. The revised criteria shown in Table 40 above reflect a per-capita fish consumption rate of 175 grams/day (where applicable). See Human Health Water Quality Standards Rulemaking for more information about these revisions.

Aquatic Life Toxics Criteria

On Jan. 7, 2015, the Environmental Quality Commission adopted revised freshwater criteria for ammonia to address EPA’s Jan. 31, 2013 disapproval of ammonia criteria adopted in 2004. EPA has not yet approved these revisions. Revised Table 30 above contains the adopted ammonia revisions. See Ammonia Rulemaking for more information about these revisions.

On April 11, 2014, EPA approved a number of revisions to Oregon’s toxics water quality standards. DEQ recommended these amendments to the Environmental Quality Commission at the commission’s Dec. 12, 2013 meeting in Portland. The revisions took effect April 18, 2014. See the Corrections and Clarifications to Toxics Water Quality Standards Rulemaking for more information about these revisions.

DEQ will address the remaining January 2013 EPA disapprovals for copper, cadmium and aluminum freshwater criteria in separate rulemakings.

Calculator for Freshwater Hardness-Dependent Metals Criteria
The toxicity of a metal to an aquatic organism can vary based on many different factors, including the route of exposure to the metal, the type and form of the metal and the physical and chemical characteristics of the water where the exposure takes place. Oregon’s aquatic life criteria for certain metals are based on water hardness. Generally, as hardness increases, the toxicity of metals decreases. The calculator below provides calculated acute and chronic criteria for certain metals based on the hardness of the water.

Metals Criteria Calculator UPDATED 4/15/14

Calculator for Freshwater and Saltwater Ammonia Criteria
The chemical form of ammonia in water consists of two species—ammonium (NH4+) and unionized ammonia (NH3). The more toxic form of ammonia to aquatic life is unionized ammonia. The ratio of these species in water is dependent upon both pH and temperature. Generally, as pH and temperature increase, the unionized, more toxic form of ammonia increases. Consequently, the ammonia criteria become more stringent. The calculator below provides calculated acute and chronic criteria based on the pH and temperature of water, and the presence or absence of salmonids or other sensitive coldwater species. Oregon’s effective freshwater acute and chronic criteria are based on equations from EPA’s 1985 304(a) ammonia criteria recommendations. The effective saltwater ammonia criteria are based on EPA’s 1989 304(a) recommendations. The final values in the calculator reflect the conversion of unionized ammonia to total ammonia nitrogen.

NOTE: DEQ will update the freshwater ammonia criteria calculator based on recently adopted ammonia criteria once EPA approves the revisions.

Ammonia Criteria Calculator

Recommendations for Analysis and Implementation of Specific Toxic Pollutants

Below is a list of memos that describe analytical methods for specific pollutants, including associated implementation and monitoring considerations. DEQ developed these memos to provide guidance to DEQ staff and other interested members of the public in response to analytical questions that have been raised on specific water quality toxics criteria. Additional memos may be posted here as other questions arise. 

Related Links

Department of Environmental Quality

Oregon Health Authority

Washington Department of Ecology

US Environmental Protection Agency


Please contact Andrea Matzke at Oregon DEQ, 503-229-5384 or by email for additional information.

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For more information on DEQ's Water Quality Division and its programs, see our contact page.

Oregon Department of Environmental Quality
Headquarters: 811 SW Sixth Ave., Portland, OR 97204-1390
Phone: 503-229-5696 or toll free in Oregon 1-800-452-4011
Oregon Telecommunications Relay Service: 1-800-735-2900  FAX: 503-229-6124

The Oregon Department of Environmental Quality is a regulatory agency authorized to protect Oregon's environment by
the State of Oregon and the Environmental Protection Agency.

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