Shared Sediments

“Sediment, by volume, is one of Pennsylvania's leading sources of waterway impairment” according to Pa's Department of Environmental Protection (DEP). Although some sediment naturally occurs in area waterways, excess sediment can be detrimental to watersheds as it decreases suitable habitat for macroinvertebrates, spawning areas for fish, and even increases water temperature by allowing more heat from the sun to be absorbed by the water. Sedimentation of area waterways occurs in a variety of ways, but many times large sources of sediment deposits can be attributed to specific problems. These usually occur as a result of a specific action. For example, restricting a stream's natural flood plain can increase the velocity of water during high flows. As the water moves through an area, this increased velocity must be subdued in order for the watershed to move back toward equilibrium. One of the ways this happens is by land in the downstream areas absorbing some of the increased force. This absorption is often times too much for the soil to handle, and the water slowly begins to remove the bank in order to make an area large enough for it to pool, and subsequently slow down.

Removal of upland vegetation allowing bare soil to wash into streams is one of the most critical sources. Another contributor to excess sedimentation can be the removal of vegetation from stream banks. Root systems of vegetation work to hold soil particles in place and slow the erosion process. By removing large woody vegetation from stream banks, we expose unprotected soil particles and allow water to remove them more easily. This usually takes place in urban and suburban yards as well as on agricultural operations. You can help alleviate excess sediment in your area's waterways by encouraging property owners to allow natural or planted vegetative strips along the waterway, or encouraging agricultural operations to limit livestock access to streams through stream bank fencing or other agricultural best management practices.

For more information on the effects of sediment on Pennsylvania streams visit the DEP's website at www.dep.state.pa.us or contact Western Pennsylvania Conservancy's Watershed Assistance Center at 724-459-0953.

Today's photo was taken by WPC staff on a farm in Bedford County.

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