Skip to main content

Oregon State Flag An official website of the State of Oregon »

Freshwater Aquatic Life Standards for Copper

DEQ has adopted a new copper water quality standard for protection of freshwater aquatic life. 

The U.S. Environmental Protection Agency approved revisions to Oregon's Aquatic Life Water Quality Standards for Copper on Jan. 9, 2017. The Oregon Environmental Quality Commission adopted the new rules on Nov. 2, 2016.   

The revisions address EPA's Jan. 31, 2013 disapproval of Oregon's freshwater copper criteria that the EQC adopted in 2004. Copper is a pollutant that can cause adverse effects to salmon, trout and other aquatic species.  

The updated copper criteria protects aquatic life based on EPA's latest 2007 national recommendations for copper. These criteria would generally apply to all freshwaters of the state.  

EPA's recommendations for copper derive site-specific criteria using the Biotic Ligand Model. This model requires inclusion of 11 different water quality parameters that affect the bioavailability and toxicity of copper in freshwaters. Many studies show that this model is a better predictor of copper toxicity than water hardness alone.

Rule language

Revised rule language: OAR 340-041-0033
Tables: OAR 340-041-8033 - Table 30 and Endnote N

Copper standard implementation

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 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 model 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.  

Rulemaking process and documents

Environmental Quality Commission action and staff report

The EQC adopted the proposed rules on Nov. 2, 2016.

Supporting documents

EPA and National Marine Fisheries Service Communication on Copper


Debra Sturdevant
Water Quality Standards Program Lead

James McConaghie
Water Quality Standard Specialist