Soil and sediment that run off the land due to erosion eventually end up in our waterways and cause water quality problems. Because of their small size, the particles of sand, silt and clay often float through the water rather than immediately settling to the bottom, which makes the water appear cloudy and muddy and creates a problem for aquatic plants that need sunlight. When the sediment settles, it becomes a substrate for aquatic weed growth and causes weeds to flourish. Sediment also carries nutrients that can further exacerbate the weed problem.
Eroding land and stream banks are sources of sediment. Watershed erosion increases when land is cleared of vegetation to make way for agriculture and development. Cleared and exposed land is prone to erosion.
Construction sites
Construction sites, if not properly managed, can produce a significant amount of sediment runoff. During rain events, exposed soil can easily move off the property into ditches and eventually into streams and lakes. The New York State Department of Environmental Conservation requires the installation of practices that will prevent sediment runoff from construction activities that disturb an acre or more of land and that contractors working on projects that disturb more than one acre to complete DEC-Endorsed Four-Hour Erosion and Sediment Control (E&SC) Training in the principles and practices of erosion and sediment control every 3 years.
Even though homeowners are not required to install erosion prevention practices when they disturb less than an acre of soil, they are strongly encouraged to do so. If soil laden runoff enters any stream or lake due to construction activity, the New York State Department of Environmental Conservation may cite the property owner with a water quality violation which may be accompanied with significant fines.
Roadside Ditches
Soil and sediment may come from improperly managed roadside ditch maintenance practices. When ditches are cleared of vegetation and not reseeded, exposed soil can easily become dislodged, enter the ditch and eventually reach streams and lakes. The Cayuga County Water Quality Management Agency has prepared Guidelines for Municipal Maintenance of Roadside Ditches (link here to this document). Further information may be obtained from Cornell University’s Local Roads Program.
Streambank erosion
Erosion of streams can be caused by natural disturbances such as a torrential rainstorm or large trees being uprooted in a windstorm, and human disturbances such as the removal of vegetated buffers and increased stormwater runoff into streams caused by the installation of impermeable surfaces and drain tiles.
Agricultural practices
In agriculture, soil erosion refers to the wearing away of a field’s topsoil by the natural physical forces of water and wind or through forces associated with farming activities such as tillage. Erosion causes the exposed topsoil, which is high in organic matter, nutrients, and soil life, to be relocated elsewhere “on-site” where it builds up over time or is carried “off-site” by precipitation events or snowmelt where it fills in drainage channels, eventually reaching our waterways.
Surface water runoff occurs whenever there is excess water on a slope that cannot be absorbed into the soil. Soil movement by rainfall (raindrop splash) is usually greatest and most noticeable during short-duration, high-intensity thunderstorms on soil without any ground cover. Runoff from agricultural land is greatest during spring months when the soils are typically saturated, snow is melting and vegetative cover is minimal.
The steeper and longer the slope of a field, the higher the risk for erosion. Soil erosion by water increases as the slope length increases due to the greater accumulation of runoff. Consolidation of small fields into larger ones often results in longer slope lengths with increased erosion potential.
Soil erosion is more likely to occur if the soil has no or very little vegetative cover of plants and/ or crop residues. Plant and residue cover protects the soil from raindrop impact and splash, tends to slow down the movement of runoff water and allows excess surface water to infiltrate.
The potential for soil erosion is also affected by tillage operations, depending on the depth, direction and timing of plowing, the type of tillage equipment and the number of passes. Generally, the less the disturbance of vegetation or residue cover at or near the surface, the more effective the tillage practice in reducing water erosion.