Clean Water and Cold-Water Refuges are Important
Water in the coast region is characterized by seasonal and annual extremes. In the winter, heavy rain causes flooding that scours salmon spawning nests and erodes riverbanks. In the summer, low streamflows and warm temperatures limit habitat for salmon. Variable ocean conditions affect food for salmon, especially juveniles. Marine heat waves, such as in 2014-2016, create poor conditions for juvenile salmon and result in low numbers of returning adults.
Summer stream conditions are changing on the coast. Along the north coast, water temperatures have remained hospitable to salmon, thanks to the Olympic Mountains’ snowpack, groundwater, and few water withdrawals. However, projections show currently pristine, high-elevation streams will be most severely affected as snowpack is reduced. Along the south coast, water temperatures already stress salmon in many low-elevation streams. Summer temperatures in small streams particularly are sensitive to shade, making stream bank protection and restoration critical. The Chehalis River is the only watershed in this region where minimum flows are protected by law. In recent years, summer flows in the Chehalis River have been so low that the Department of Ecology restricted withdrawals for some water right-holders so enough water would remain in the river for salmon.