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Living With the Methow River Monthly Activities and Learning Opportunities July 2017
Sediment Monitoring Each year's high flow sees the river reshape its banks and gravel bars. Rushing water erodes land and carries sand, silt, and organic material downstream, stripping it from fast sections and depositing it where the water slows. Though sediment is a natural part of streams and rivers, too much sediment is bad news for fish. Salmon lay their eggs in clean cobbles and gravel. The cobbles protect the eggs while allowing water to flow around them. Young salmon and the invertebrates they feed on both live in the open spaces between river-bottom cobbles. If sediment fills in these open spaces, the eggs and invertebrates may suffocate, and young fish may find themselves without cover or food. High turbidity (cloudy water caused by suspended sediment) can also clog gills and block sunlight from reaching underwater plants and algae. Sediment is often released by human activity. Mining, cattle grazing, dredging, construction, and other activities can introduce sediment into river systems, or stir up sediment that had previously settled. This sediment, if it comes at the wrong time, can be deadly for fish. Work in the river, even work to restore habitat, must be carefully timed to prevent the release of sediment when these species are most vulnerable. Of course, human activity is not the only cause of excessive sediment. Recent wildfires in the Methow stripped vegetation and destabilized slopes, and flooding afterwards washed an enormous amount of sediment into the river system. By monitoring the amount of sediment present in spawning areas, and comparing this to other data, we can better understand the impacts of natural and human-caused sediment release on native fish. A better understanding of both the species and their habitat helps us to assess the health of the watershed and plan better projects to improve it.
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This year’s MRC calendar connects to ADVENTURES, ACTIVITIES AND INFORMATION tailored to each month. If you haven't gotten your calendar yet, you can download an electronic version here. Come back each month and find interactive activities, print outs, and suggested learning opportunities in our community.
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