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Release Date: 4/21/1997
Contact Information: Dave Schmidt, U.S. EPA, (415) 744-1578

     (San Francisco) -- The U.S. Environmental Protection Agency (U.S. EPA), the U.S. Department of Justice, and the U.S. Attorney for Arizona today filed an agreement in federal district court to settle a lawsuit with the Defenders of Wildlife, an environmental group, concerning mercury pollution problems in Arizona.  In the settlement, U.S. EPA has made a legal commitment guaranteeing that pollution reduction targets, known as Total Maximum Daily Loads (TMDLs), will be established within 4 years for 13 Arizona river segments and lakes impacted by mercury..  

     "We share Defenders of Wildlife's goal of taking action to protect Arizona's rivers, wildlife, and people from  mercury contamination," said Felicia Marcus, Regional Administrator of U.S. EPA.  "We're pleased to be able to agree on a rapid but reasonable timeframe to work with the State and other interested parties to get it done."

     A Total Maximum Daily Load, as the name implies, is the amount of a pollutant a waterway can absorb, plus a margin of safety, and still meet water quality standards, including designated uses such as drinking water, aquatic life, and recreation.   A TMDL includes a quantitative assessment of water quality problems, pollution sources, and pollution reductions needed to restore and protect a river, stream, or lake.

     The TMDL process, under the federal Clean Water Act, provides a framework for assessing the environmental problems in a watershed and identifying pollution reductions needed to protect drinking water, aquatic life, recreation, and other uses of rivers, lakes, and streams.  The Clean Water Act gives state governments primary responsibility for establishing TMDLs, though U.S. EPA can also develop them.  The State of Arizona, which was not a party to the lawsuit,  has already made commitments to establish TMDLs in several watersheds not covered by the agreement, and has the option of establishing TMDLs on some or all of  the 13 river segments and lakes that are designated in the agreement.  The agreement, however, commits U.S. EPA to establish TMDLs within the next 4 years for the 13 specified waters if they are not addressed by the State.
     "This is a great opportunity to tackle the problem of mercury pollution in Arizona's
waterways," said U.S. Attorney Janet Napolitano. "This agreement is a solid step towards ensuring that we all work together to prevent excessive mercury from entering Arizona's waterways."

     U.S. EPA plans to work with state agencies, local governments, landowners and other stakeholders, and federal land management agencies  in many basins to help develop TMDLs in conjunction with ongoing water quality assessment and planning efforts.  TMDLs for mercury are needed on the 13 river segments and lakes listed in the agreement because existing pollution controls may be insufficient to curb excessive mercury loads on these streams and lakes.  Because mercury can accumulate in animal tissues in higher concentrations as it goes up the food chain, excessive mercury loads in streams and lakes can harm wildlife, including bald eagles and other endangered species.  It can also harm people who consume contaminated fish or meat from other animals.  

     The agreement covers Pena Blanca Lake, Arivaca Lake, Silver Creek from Show Low to Cottonwood, Painted Rock Lake, Salt River from Granite Reef to the Gila River, and several segments of the Gila River downstream from Phoenix to Painted Rock Lake.

     The plaintiffs involved in the settlement are the Defenders of Wildlife and three Arizona residents.

     Nationally, there are over 20 pending or active lawsuits related to the Clean Water Act TMDL program.  This settlement is the second TMDL lawsuit settled in U.S. EPA's western region.  More information can be accessed on our Internet homepage at

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