Sediment and Erosion
Sediment in streams and lakes has detrimental effects on water quality and water quantity. Soil that erodes from the land and from within stream channels settles in the bottoms of lakes and ponds thereby reducing their water-holding capacity, a process called “sedimentation”. Sediment is also a water pollutant, can transport other pollutants such as pesticides and nutrients attached to soil particles and has a negative impact on biological organisms in the water.
Over time, most lakes will eventually fill with sediment. Under natural conditions this process normally takes many years to run its course. However, human activity in the watershed tends to accelerate erosion and cause more rapid deposition of sediment in lakes and ponds. Activities that contribute to accelerated sedimentation rates in the Delaware River Watershed include the cultivation of cropland, poor grazing practices, construction activity, and removal of trees from the banks of streams. Straightening of stream channels, which increases the velocity and erosive power of stream flows, also contributes to the erosion of stream beds and streambanks.
Sedimentation that is occurring in Perry Lake Reservoir, the largest lake in the Delaware River Watershed, is an issue of great concern (see photo at right). Sediment has already reduced the lake's water-holding capacity, negatively impacted recreation and water quality, and will ultimately diminish the flood control capabilities of the reservoir.
Research has shown that erosion occurring within the channel of the Delaware River itself is a significant source of sediment being delivered to Perry Lake. Straightening of
the river that occurred decades ago caused the river
to cut deep into the surrounding floodplain, creating steep, unstable
riverbanks that are easily undermined and eroded away. The removal of
deep-rooted trees from riparian areas along the river and other
agricultural practices have also contributed to bank instability and
increased streambank erosion. More detailed information on sedimentation
in the Delaware River basin can be found in the Delaware River WRAPS
plan.
What you can do . . .
- Stabilize eroding stream banks with vegetation -- Trees, shrubs and native grasses have deep root systems that hold on to soil, slow down the erosive force of water and filter contaminants out of runoff.
- Stabilize sloping land with grasses or other ground covers -- Perennial vegetation that provides cover for sloping land holds soil in place and purifies runoff. Native grasses which are deep-rooted and tough are some of the best choices for this purpose.
- Practice no-till or reduced tillage to maintain residue on crop fields -- Crop residue stops erosion. Studies show that practicing continuous no-till reduces cropland erosion by 80% or more.
- Plant cover crops after cash crops are harvested -- Cover crops keep the soil covered, improve soil organic matter, enhance biological activity and and increase the moisture-holding capacity of the soil. Improved soil quality can help farmers improve their crop yields and reduce crop inputs (like fertilizer and pesticides).
- Reduce erosion from construction areas -- Bare soil is vulnerable to erosion. Reducing the amount of soil that is exposed and planting vegetation as quickly as possible following construction helps.
- Keep livestock out of streams and areas around streams -- Livestock cause erosion by trampling vegetation, breaking down bank soil structure, and churning up stream beds. Reduce this impact by feeding livestock and providing water, shade and protection from wind as far away from streams or ponds as possible. Sensitive riparian areas should be fenced off to limit livestock access.
- Plant buffer strips between livestock lots and streams -- Buffers planted to grass and/or trees stabilize soils and filter out sediment, manure and other pollutants (like nutrients and bacteria) before they reach a stream.
- Manage pastures to reduce erosion -- Good pasture management reduces erosion by maintaining vigorous grass growth year-round.
- Practice backyard conservation -- You can reduce erosion, protect water quality and turn your backyard into a wildlife sanctuary. Check out the "Library" section of the website for ideas and publications that can help.
Get help with other erosion problems from local conservation groups -- The Resource Partners section of this website has links to organizations and agencies such as county conservation and joint watershed districts that can help you determine ways to reduce complex erosion problems on your property.