Protecting Oregon's Environment
Oregon State Seal
Oregon Department of Environmental Quality

Water Quality

Water Quality Standards

Sign up to get email notices on human health toxics criteria revisions

Standards Home
Review and Rulemaking
Rules and Regulations
Beneficial Uses
Related Info

 WQ Info Guides:
by alphabet
by category

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 as a result of EPA approval on Oct. 17, 2011 (minor updates effective on April 18, 2014).
Aquatic Life Criteria
Table 30 Effective aquatic life criteria as a result of EPA approval on April 11, 2014. Effective on April 18, 2014.
Table 31 Guidance values ONLY (minor updates effective on April 18, 2014)
Tables 30, 31, and 40

Toxics Standards Rule (OAR 340-041-0033)

Human Health Toxics Criteria

On June 1, 2010, EPA disapproved the majority of the human health criteria adopted by the EQC in May 2004. EPA concluded that the criteria values were based on a fish consumption rate that was too low (17.5 grams/day) to protect many fish consumers in Oregon.  After an extensive review of the fish consumption rate, DEQ revised the human health toxics criteria based on a higher per capita fish consumption rate of 175 grams/day. These criteria are now incorporated into Table 40 and are effective under state and federal law for Clean Water Act programs. Table 40 criteria became effective following EQC adoption on June 16, 2011, and EPA approval on Oct. 17, 2011 (non-substantive updates to Table 40 are effective on April 18, 2014). EPA approved revisions to the manganese criteria and withdrawal of iron on June 9, 2011. These revisions are reflected in Table 40. 

Aquatic Life Toxics Criteria

On April 11, 2014, the U.S. Environmental Protection Agency approved all revisions to Oregon’s toxics water quality standards. DEQ recommended these amendments to the Environmental Quality Commission at its Dec. 12, 2013 meeting in Portland. The revisions are effective on April 18, 2014 for all Clean Water Act programs.

EPA Approval Letter and Technical Support Document

The revisions address EPA’s Jan. 31, 2013 disapproval of 11 pesticides and selenium aquatic life criteria, and reinstate criteria for arsenic and chromium VI that were inadvertently omitted from a toxics table. In addition, the revisions consolidated all the toxics aquatic life criteria into one new table - Table 30. DEQ will address the remaining January 2013 EPA disapprovals for ammonia, copper, cadmium and aluminum in separate rulemakings. Until such time revised criteria are approved, criteria for these pollutants will reflect criteria last approved by EPA. 

EPA did not take action on a number of other minor revisions related to this rulemaking. Most of these revisions became effective on Dec. 23, 2013. For these revisions, please see rulemaking documents on the agency’s Rules and Regulations web page.

See EPA Action on Oregon's Aquatic Life Criteria for more information.

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.

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.

[print version]

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.

DEQ Web site privacy notice