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The Minnesota Pollution Control Agency Approach to Developing Site-Specific Water Quality Standards for Pollutants and Nutrients

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The current US Environmental Protection Agency [EPA] administrative focus of their site-specific modifications to water quality standards (WQS) is specific to toxics [e.g. Water Quality Standards Handbook – Second Edition, Section 3.7 Site-Specific Aquatic Life Criteria, pages 3–38 through 3–45]. New to the scene and demanding our state's immediate attention are excess nutrients and conventional pollutants. The Minnesota Pollution Control Agency [MPCA] is developing guidelines to deal with these pollutants. We will provide examples for lakes of how site-specific water quality standards [SS WQS] might be developed for these pollutants.

Three tools used for SS modifications are Use Attainability Analyses [UAAs], site-specific water quality standards [SS WQS], and variances. Here is how the MPCA distinguishes them.

The initial question is “Will designated uses be met with the proposed modifications to the WQS?” If yes, the appropriate tool is the SS WQS. If no, the next question is “Did the use exist on or after November 28, 1975? If yes, UAAs are not a viable option. If no, the next question is “Is the loss of designated use permanent or temporary?” If the loss of use is temporary, the appropriate tool is the use of a variance. If the loss of use is permanent, the appropriate tool is the UAA.

EPA Region 5 Water Quality Branch released Regional Technical Assistance #1 on September 13, 2007, titled Information for States and Tribes on submittal of new and/or revised water quality standards to U.S. EPA for review under section 303(c) of the Clean Water Act and Federal regulations at 40 CFR 131. This very detailed document describes relevant federal regulations, minimum components of a WQS submittal for EPA review, and documentation requirements by type of submittal.

40 CFR 131.11(b)(1)(ii) provides states with the opportunity to adopt water criteria that are “ … modified to reflect site-specific conditions.” However, the three procedures described: recalculation procedure, Water-Effect Ratio procedure, and Resident Species procedure are all designed to deal with toxics; none deal with nutrients or conventional pollutants.

The MPCA has been listing lakes with excess nutrients since the 2002 Total Maximum Daily Load [TMDL] listing cycle. The 2008 TMDL List contains 329 lakes with excess nutrients. Until numeric water quality standards for lakes, based on ecoregion expectations, were recently approved, the MPCA has been using ecoregion numeric translators of the narrative WQS prohibiting excess algae [, document pages 62 – 82].

Nutrient TMDLs require that reductions result in meeting water quality standards. Even though these standards are more regional than statewide WQS, they are still very broad-brush and lakes near ecoregion boundaries or “different from ecoregion expectations” may not be able to meet nutrient water quality standards.

Because there are no federal “procedures”, the MPCA has developed a process that we believe meets both state and federal regulations. The process begins with the development of reduction goals, the draft TMDL. The few lakes that naturally can not meet existing WQS can not submit approvable TMDLs until SS WQS is in place.

Once the scientifically defensible SS WQS documentation is developed and all pertinent Agency documents are placed on the Agency web page, the public participation component begins. A Minnesota State Register notice is developed that contains the background to the impairment and the SS WQS recommendations.

Three options are available: comments regarding the State Register notice may be submitted to the Agency for review and comment and/or a request for a public meeting may be made and/or a request that the issue be brought before the MPCA Citizens' Board as an information item may be made. All comments made and all Agency responses are forwarded to US EPA as part of the SS WQS packet for their review and approval. Once the SS WQS is approved, the TMDL can then be submitted for review and approval by US EPA. Both the SS WQS and the TMDL can be submitted together, but the TMDL review will be held up until the SS WQS request is determined.

Document Type: Research Article


Publication date: 2009-01-01

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