Water Quality Standards
Water Quality Standards for Toxic Pollutants
Water quality standards are the foundation of the water quality-based control program mandated by the federal Clean Water Act. Water quality standards define goals for surface waters in Oregon by designating 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, 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 Toxic Standards
Toxics standards rule (OAR 340-041-0033)
Human Health and Aquatic Life Criteria Tables
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.
On Jan. 31, 2013 EPA disapproved a number of aquatic life criteria that the Environmental Quality Commission adopted in 2004. The pollutants included pesticides, cadmium (acute only), copper, ammonia and aluminum. Since 2013, DEQ adopted and EPA approved revisions to several of the disapproved criteria.
On Jan. 9, 2017, EPA approved the revisions to Oregon‘s freshwater aquatic life standard for copper. For more information, see the Copper Rulemaking website.
On Jan. 10, 2017, EPA promulgated an acute freshwater aquatic life criteria for cadmium for Oregon into federal regulations. See the federal regulation for cadmium.
On Aug. 4, 2015, EPA approved revisions to Oregon’s ammonia water quality standards for the protection of aquatic life. These criteria are now effective for all Clean Water Act programs in Oregon. Table 30 above contains the effective ammonia criteria.DEQ will update Oregon Administrative Rules 340-041-0033 and 340-041-8033 to reflect EPA’s approval in a subsequent rulemaking.
See Ammonia Rulemaking for more information about these revisions.
Implementation Information for Toxics Criteria
Calculator for Freshwater Hardness-Dependent Metals Criteria
The toxicity of a metal to an aquatic organism can vary based on many different factors, including route of exposure to the metal, type and form of the metal and the physical/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 acute and chronic criteria for certain metals based on water hardness.
Acute cadmium criterion
The new federal acute hardness-based criterion for cadmium changes the hardness-based equation coefficients for the acute cadmium criterion and establishes new default hardness values by region.
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 un-ionized ammonia. The ratio of these species in freshwater is dependent on both pH and temperature. Generally, as pH and temperature increase, the un-ionized, more toxic form of ammonia increases. Consequently, the ammonia criteria become more stringent. The calculator below calculates acute and chronic saltwater criteria based on pH, temperature, salinity and pressure. The saltwater ammonia criteria are based on EPA recommendations made in 1989 in Section 304(a) of the Clean Water Act. The final values in the calculator reflect the conversion of un-ionized ammonia to total ammonia nitrogen. DEQ will update the freshwater ammonia criteria calculator based on EPA’s Aug. 4, 2015 approval of revised criteria in the near future. In the interim, the look-up tables for freshwater ammonia criteria based on pH and temperature may be found in Table 30 above.
Copper Biotic Ligand Model
The toxicity of copper varies in aquatic environments because the bioavailability of copper changes based on water chemistry conditions. The Biotic Ligand Model determines copper toxicity for a given set of conditions by using measurements of ten different water quality parameters that affect copper toxicity to aquatic organisms. These parameters are pH, dissolved organic carbon (DOC), temperature, calcium, magnesium, sodium, potassium, sulfate, chloride, and alkalinity. The Biotic Ligand Model provides site-specific acute and chronic copper criteria that reflect changes to copper bioavailability caused by interaction with these water chemistry variables. Using the BLM provides a high degree of protection to aquatic life during vulnerable water chemistry conditions and will also identify those conditions that are less sensitive, where toxicity occurs at greater copper concentrations. The Biotic Ligand Model software and information on implementation procedures are available on the Copper Biotic Ligand Model Implementation website (available February 2017).
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.
Department of Environmental Quality
Oregon Health Authority
Washington Department of Ecology
U.S. Environmental Protection Agency
For more information on DEQ's Water Quality Division and its programs, see our contact page.