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Water Quality Standards Revisions for Freshwater Ammonia​ 2014


The public comment period on proposed amendments to Oregon’s freshwater ammonia criteria closed on Oct. 30, 2014. DEQ will consider all comments received before presenting its recommendations to the Environmental Quality Commission at its meeting Jan. 7-8 in Portland. See rulemaking documents on DEQ’s Rules and Regulations page.
DEQ has proposed a rulemaking to address EPA’s Jan. 31, 2013 disapproval of ammonia criteria that the 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 August 12, 2013.
As part of the rulemaking, DEQ is also proposing to correct an error to the pH rule for the main stem Snake River, and add notes to the statewide narrative natural conditions criterion and numeric natural conditions criterion for temperature to reflect EPA’s disapproval action. In addition, DEQ is proposing to correct or clarify  site-specific water quality standards for the West Division Main Canal, an irrigation canal near Hermiston, Oregon.
DEQ held an ammonia 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 below for more information. DEQ did not accept public comment during the webinar.

Ammonia Webinar—September 10, 10-12 PDT




EPA’s Jan. 31, 2013 disapproval of Oregon’s ammonia criteria results in Oregon retaining its currently effective ammonia criteria that are based on EPA recommendations from 1985 (criteria last approved by EPA). These criteria are in Table 30 and are dependent on pH and temperature using the ammonia calculator located on the toxics website. Until Oregon adopts revised criteria for ammonia and EPA approves those revisions, the criteria in Table 30 remain effective for Clean Water Act purposes.

DEQ proposes to adopt revised ammonia criteria to protect freshwater mussels and snails. Current information indicates that freshwater mussels and snails are present in many watersheds across Oregon. DEQ’s proposed ammonia criteria follow EPA’s August 2013 recommendations. EPA’s criteria are expressed as Total Ammonia Nitrogen (TAN) and are dependent on the pH and temperature of the water. See EPA’s website for more information about its ammonia recommendations.

Prior to initiating 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. Members of the public will have an opportunity to provide comments on the rulemaking as part of the public comment process.

In addition to ammonia revisions, the proposed rule would correct 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 would correct that error to ensure that the pH standard applies throughout the main stem Snake River in Oregon. DEQ also proposes to add 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 proposes to amend basin-specific standards for the Umatilla Basin and remove 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 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 action May 2015 (estimated)



Stay informed about the ammonia rulemaking by clicking the green envelope at the top left corner of this page to be added to DEQ’s mailing list for water quality standards rulemaking. Information related to the ammonia rulemaking will also be added to this website as it becomes available.