Fresh Waters

Duckabush River Side Channel (S. Smith/PNPTC)

A warming climate can have many impacts on fresh water, including increased temperatures of lakes and streams, changes in dissolved oxygen levels, increased sediment in streams and lakes, and changes in fresh water availability due to a reduction in snow and ice-cover.

Changes in precipitation, evaporation and flooding dynamics can affect water levels, habitat structure and water residence times in wetlands. Small intermittent streams and small lakes in warm dry areas may disappear, while flow in permanent streams may become intermittent or reach critically low flows in the summer months. Systems already at the threshold are most likely to change abruptly. Tribes throughout western Washington are monitoring these freshwater areas now.

With more precipitation falling as rain rather than snow, winter streamflow is expected to increase, and the lack of snowpack will reduce spring and summer flows. Increased glacier melting in streams with glaciated headwaters may add to summer stream flows in the short term, but the reduction and eventual disappearance of glaciers will ultimately reduce summer flows. Water temperatures are also expected to increase, causing negative impacts on culturally and economically valuable fish such as salmon. Additional impacts such as increased sediment transport during winter months and changes in water quality are also expected to adversely affect stream habitats and water availability.

View more climate impacts