Sunday, August 14, 2011

Glacial Milk in Western Washington Rivers

North Fork Nooksack River

During my first visit to Mount Rainier National Park I learned about glacial milk. The finely ground sediment from glaciers incorporated into glacial fed streams and rivers give the stream or river a milky color. Rivers flowing off of Mount Rainier with its mantling with big glaciers are very milky. The Nisqually River fed by the Nisqually Glacier on Rainier takes on a milky appearance this time of year.

Numerous rivers flowing in the North Cascades in western Washington have a milky look this time of year due to glacial melt. The North Fork Nooksack and Middle Fork Nooksack are both very cloudy as both derive water from the glaciers on Mount Baker. The North Fork's head waters are in Nooksack Cirque and is fed by glaciers on the north side of Mount Shucksan. The Nooksack remains cloudy with silt all the way to Bellingham Bay.

The Skagit River is not as cloudy as the main stem of the river and one of its main tributaries, the Baker River are dammed and hence much of the silt settles out. There is still some siltiness from other glacier fed tributaries such as the Cascade River.    

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