The Rocky River Watershed Council has identified sedimentation as a habitat impairment within the Rocky River Watershed. The primary cause of sedimentation in the watershed has been identified as erosion. What exactly are sedimentation and erosion? Why are they detrimental to our rivers and lakes? And what can we do about it?
Sedimentation is the process of sediment particles being carried from one point and deposited elsewhere. Sources of sedimentation are both natural and man-made and can include natural stream erosion, construction sites, deforested areas, and agricultural lands. As water travels over unvegetated streambanks and land with uncovered soil, it picks up sediment particles and transports them downstream.
Erosion is the process of soil particles becoming detached and moved by natural forces like water and wind. Streambank erosion is a natural process; however changes to a natural stream channel often cause an acceleration of the erosion process. When stream channels are straightened, widened, or blocked; when streamside vegetation is removed; or when land use changes contribute to increased runoff, erosion rates can increase. Water quality, aquatic habitat, stream recreation, and industry are all affected by increased sediment loads from erosion.
As sediment load is carried by streams, fine sediment particles (suspended sediment) settle out of the water and start to fill in and clog stream channels and lake bottoms. This accumulation and concentration of fine sediments is called siltation. Siltation clogs important macroinvertebrate (bug) and fish habitat. Increased suspended sediment in the water column contributes to increased turbidity which reduces visibility for aquatic organisms that need to see to eat. Sediment can also carry nutrients, pesticides, and toxic compounds which all lower water quality.
Cuyahoga SWCDs storm water program targets the limitation of sedimentation from county construction practices through recommending preventative and remedial measures like:
- Reduction of sediment excess from construction activities (limiting site access, using silt fences, stabilizing post construction areas with vegetation)
- Construction of detention, sediment, or settling basins/ponds
Watershed groups like the Rocky River Watershed Council target the limitation of sedimentation from streambank erosion through public outreach, education, and streambank restoration projects. Streambank restoration may include vegetating streambanks or restoring the stream channel dimensions back to a natural state. For more information on how the Rocky River Watershed Council is addressing streambank erosion see the Saving Baldwin Creek from Streambank Erosion blog.
For more information on what you can do to help, contact our watershed staff.