Water Quality

On Aug. 4, 2015, the U.S. Environmental Protection Agency 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. The Oregon Environmental Quality Commission adopted ammonia criteria and other minor revisions on Jan. 7, 2015. EPA’s approval also included a correction to the pH value applicable to the Snake River, and revisions to the West Division Main Canal water quality standards in the Umatilla Basin.


On Jan. 31, 2013, the EPA disapproved ammonia freshwater criteria that the Oregon Environmental Quality Commission adopted in 2004. Oregon’s adopted criteria were based on EPA’s 1999 recommended criteria, which did not take into consideration ammonia toxicity to certain kinds of freshwater mussels and snails. EPA has since updated its national recommendation for ammonia in response to new mussel and snail sensitivity data, and published final revised criteria in the Federal Register on Aug. 12, 2013. Oregon adopted EPA’s latest recommendations. See EPA’s website for more information about its ammonia recommendations. 
The revised ammonia criteria protect sensitive freshwater mussels and snails, including other aquatic species. Current information indicates that freshwater mussels and snails are present in many waterbodies across Oregon. The adopted criteria are expressed as Total Ammonia Nitrogen (NH3 and NH4) and continue to be dependent on the pH and temperature of water.
Before starting this rulemaking, DEQ met with stakeholders to discuss EPA’s latest ammonia recommendations and its potential application to Oregon waterbodies. Feedback received indicated that generally, EPA’s recommendations are appropriate for Oregon and that DEQ should move forward quickly to adopt revisions. Given this input, DEQ did not form an advisory committee for this rulemaking.
In addition to ammonia revisions, the adopted rule corrects an error made in 2003 for the basin-specific pH standard for the main stem Snake River. The current standard incorrectly identifies river miles 260-335 for the Snake River. This rule revision corrects that error to ensure that the pH standard applies throughout the main stem Snake River in Oregon.
DEQ also added notes to the statewide narrative natural conditions criterion at OAR 340-041-0007(2) and numeric natural conditions criterion under the temperature standard informing the reader that due to EPA's disapproval of these provisions, the conditions are no longer applicable for federal Clean Water Act purposes. Finally, DEQ amended basin-specific standards for the Umatilla Basin and removed a term from the definitions section to be consistent with EPA’s partial disapproval of site-specific criteria and use designations for the West Division Main Canal near Hermiston that EQC adopted in 2012.

Ammonia Webinar - Sept. 10, 2014

DEQ held an ammonia standards webinar on Sept. 10, 2014 to provide information about this rulemaking to the public prior to the public comment period. See webinar agenda and presentation for more information.

DEQ took public comment from Sept. 16 to Oct. 30, 2014. DEQ received five comments. The EQC adopted the ammonia revisions on Jan. 7, 2015.

Ammonia Rulemaking Schedule - Milestones and Timeframes
  • Initiate rulemaking - April 2014
  • Public webinar - Sept. 10, 2014
  • Public comment - Sept. 16 – Oct. 30, 2014
  • Public hearing (Portland) - Oct. 15, 2014
  • Environmental Quality Commission adoption - Jan. 7 – 8, 2015
  • EPA approval - Aug. 4, 2015