In September 2006, the Oregon Department of Environmental Quality (ODEQ) finalized the first phase of a Total Maximum Daily Load (TMDL) for mercury in the Willamette River. This final version illustrates both the strengths and the weaknesses of the TMDL program in achieving improved
water quality. The TMDL was prepared because fish tissue from several species of fish in the Willamette Basin exceeded the recommended mercury concentration of 0.35 milligrams per kilogram (mg/kg, wet weight), prompting the Oregon Department of Human Services (ODHS) to issue fish consumption
advisories for the mainstem of the Willamette River, and for the Dorena and Cottage Grove Reservoirs. On the basis of these fish advisories, the Willamette River and tributaries were designated as impaired waters, and ODEQ prepared a TMDL to determine actions needed to address this impairment.
Submitted to the U. S. Environmental Protection Agency on September 21, 2006 and approved 8 days later, the first phase of this TMDL will help to focus mercury reduction efforts on pathways leading to the aquatic environment, complimenting mercury reduction efforts that are currently dominated
within DEQ by a solid waste perspective. The challenge to those moving forward to implement the TMDL is twofold. For National Pollutant Discharge Elimination System (NPDES) permittees, the challenge is to maintain the mercury reduction focus over several adaptive management cycles in the face
of scientific uncertainty about how to achieve detectable improvement in the measures of water quality in the Willamette River. For sources of non-point pollution, the challenge is to increase their pace of action toward measurable achievements in mercury load reduction, also in the face of
uncertainty. After setting the framework for mercury reduction plans, ODEQ will ask for implementation plans for this TMDL required of NPDES permitted discharges to be finalized within 12 months. Directions will be set for obtaining technical information to substantiate the second phase of
the TMDL scheduled to be developed in 201l. Strategies for compliance and mercury reduction being promoted by municipal dischargers in Oregon will be useful models for others facing similar TMDL challenges.
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