• 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.