Loss of floodplain, riparian habitat, and river complexity resulting from a range of agricultural and urban development over the decades. In addition to poor fish passage at dams on the tributaries, this has resulted in a Threatened listing for Spring Chinook salmon under the Federal Endangered Species Act.
Water quality violations for temperature, bacteria, and mercury. Increases in pesticides, as well as emerging contaminants such as flame retardants.
Continued permitted point-source pollution.
Non point-source pollution or runoff from urban and rural areas.
Large dams on the major tributaries that significantly block fish passage, resulting in a Biological Opinion that is being slowly implemented at best to improve fish passage.
Fish consumption advisories due to mercury and PCBs.
Stormwater overflows that increase bacteria levels.
Increased blue-green algae during the summer months in some areas.
A massive Superfund site in Portland Harbor - with 10 miles of contaminated sediments polluted with historic chemicals such as PCBs, DDT, and oil-based pollutants.