A new report on the dumping of toxic wastes into American rivers names the two biggest dischargers into Oregon waters, Portland's Siltronic Corp. and the Georgia-Pacific mill in Toledo. 

The report was written by the Boston-based Environment America Research & Policy Center and the Frontier Group in Santa Barbara, Calif. It was released in Portland through the Environment Oregon Research & Policy Center.

The report, "Wasting Our Waterways: Toxic Industrial Pollution and Restoring the Promise of the Clean Water Act," measured discharges as reported by industries under the U.S. Environmental Protection Agency’s Toxic Release Inventory. Researchers found industry released 206 million pounds of toxic chemicals into American waterways in 2012. 

According to the report, Siltronic, a Northwest Portland semiconductor manufacturer based on the lower Willamette River, released 350,562 pounds of toxic wastes that year, making it No. 1 in Oregon for total discharges by weight. (Siltronic was recently a financial force behind the failed May primary ballot measure that would have created a new water board in the city of Portland.) 

The report cites the Georgia Pacific mill, located on the Siletz River, as the top polluter based on the toxicity of its releases. The calculation is based on an EPA measurement that produces a “toxicity-weighted pound equivalent,” which measures the potency of the chemicals being released. 

Overall, the report says, Oregon is ranked 33rd in pollution released by pound, and 20th based on the weighting of the pollutants’ toxicity.