Willamette Basin Mercury Study

Overview

The Oregon Department of Environmental Quality (ODEQ) is committed to developing Total Maximum Daily Loads (TMDLs) to address the parameters listed on the State’s 1998 303(d) list. There are currently ten listings for mercury in the Willamette Basin on the State’s list of impaired waterbodies. The listings for mercury in the Willamette extend from the Cottage Grove and Dorena Reservoirs (in the Coast Fork Subbasin) to the mouth of the Willamette River. DEQ based 303(d) mercury listings on the Health (fish consumption) Advisories issued by the OHD. Willamette Mercury Phase II Study begins in 2007

Study Objectives

Oregon DEQ designed the Willamette Basin Mercury Study to address 303(d) listings and describe the following objectives:

1. Describe the relationship between mercury in fish tissue and mercury in the water column for the development of a site-specific bioaccumulation factor.
2. Describe the relationship between methylmercury in water and total mercury in water and sediment.
3. Begin to identify and quantify the sources and loadings of mercury in the Willamette River system.

Monitoring

• Phase I  2002-2003 

• Phase II  2007-2008

How Data is Used

• Willamette TMDL
• DHS Fish Consumption Advisories
• USEPA Fish tissue criterion