NACWA Regulatory Alert (RA 07-03)

Action Please By:
May 18, 2007

On April 3, NACWA met with officials from the U.S. Environmental Protection Agency’s (EPA’s) Office of Science and Technology to discuss possible revisions to the 1999 water quality criteria for ammonia. Since announcing that it would reevaluate the criteria in July 2004, EPA has worked to conduct several new studies to further document the effects of ammonia on freshwater mussels and address other concerns raised by stakeholders. NACWA’s meeting with EPA was a preliminary step in what will likely be a two- to three-year process to develop and finalize a set of revised criteria. During the meeting, EPA Office of Science and Technology Director Ephraim King asked NACWA to provide the Agency with any additional scientific information it had pertaining to ammonia toxicity, specifically its impact on freshwater mussels. As detailed below, the revised criteria could be two to three times more stringent than the 1999 criteria. EPA is interested in receiving any additional scientific information regarding ammonia toxicity or ammonia’s potential impacts on freshwater mussels. NACWA has informed EPA that more stringent criteria may pose implementation problems for the Nation’s clean water agencies and is interested in learning what potential impacts the more stringent ammonia criteria might have on your facility. If you have any information that might help, please forward it to Chris Hornback, NACWA’s Senior Director of Regulatory Affairs at chornback@nacwa.org by May 18.

EPA will be making critical decisions about its next steps this summer and the information NACWA is requesting will be provided to EPA to help the Agency in its decision-making process. Additional information on EPA’s ammonia criteria, the July 2004 notice, and a workshop on mussel toxicity held in 2005 are available on EPA’s website (http://www.epa.gov/waterscience/criteria/ammonia/).

Potential Impacts Prior to Criteria Revision
EPA’s efforts to revise the criteria are being closely monitored by the U.S. Fish and Wildlife Service due to ammonia’s potential effects on a number of threatened and endangered mussel species. It is possible that the new information on ammonia’s toxicity to mussels may have implications even before EPA has a chance to revise the criteria during EPA review of state water quality standards or National Pollutant Discharge Elimination System (NPDES) permits that use the 1999 criteria. In fact, the Environmental Law & Policy Center, in a letter to EPA late last year, raised concerns that EPA has failed to protect endangered species by not objecting to state-issued permits that use the old criteria. In its response to the Environment Law & Policy Center, EPA noted that it its authority only allows it to consider whether a permit is written to meet the current state water quality standards. A more likely challenge may result from EPA’s review of state water quality standards that include the 1999 criteria. How EPA will handle those reviews now that it has information that the criteria may not be protective in all cases remains to be seen.

Additional Information on New Ammonia Studies
While NACWA’s comments (http://www.nacwa.org/getfile.cfm?fn=2004-09-08OW-2004-0012Cmts.pdf) on EPA’s July 2004 notice were critical of the new mussel toxicity studies for their use of unique life stages and an un-approved test protocol, the new information presented to NACWA at its April 3rd meeting with EPA does reinforce the earlier studies and appears to address many of the concerns raised in the NACWA comments. The primary study that led EPA to collect the additional information, Augspurger et al. (2003)¹, indicates that incorporating the freshwater mussel data would lower the existing federal maximum criteria by 60 to 75 percent and would lower the existing federal average criteria by 20 to 75 percent.

EPA now believes the concerns expressed by NACWA and others in 2004 have been adequately addressed and is prepared to proceed with revision of its ammonia criteria. Although EPA is not yet ready to propose specific numeric values, preliminary estimates have indicated that the resulting criteria will be at levels approximately 1/3 of the existing acute criteria applicable where salmonids are assumed present and 1/4 of the existing acute criteria applicable where salmonids are assumed absent. Data are now believed to be sufficient to also derive chronic criteria protective of freshwater mussels.

Implementation Issues
During the April 3rd meeting, NACWA urged EPA to include, with its publication of the criteria, guidance that advises states on the flexibility that is available to them in implementing the criteria. In particular, site-specific considerations of the species present, the relationship between temperature and mussel toxicity, seasonality, and exposure frequency and duration need to be factored into the criteria implementation. These implementation issues will be a focus of NACWA’s advocacy on this issue and NACWA is interested in hearing from its members on other possible implementation problems should the criteria be revised.

Again, EPA is interested in receiving any additional scientific information regarding ammonia toxicity or ammonia’s potential impacts on freshwater mussels and NACWA is interested in learning what potential impacts the more stringent ammonia criteria might have on your facility. If you have any information that might help, please forward it to Chris Hornback, NACWA’s Senior Director of Regulatory Affairs at chornback@nacwa.org by May 18.

¹ Augspurger, T., A.E. Keller, M.C. Black, W.G. Cope, F.J. Dwyer. 2003. Water quality guidance for protection of freshwater mussels (Unionidae) from ammonia exposure. Environ. Toxicol. Chem. 22(11): 2569-2575.