|
|
|
| SEDIMENTSediment is eroded soil particles. Erosion occurs when rain or moving water dislodges and carries soil particles, organic matter, and plant nutrients as it flows. The process of erosion creates excess sediment. This sediment is considered an NPS pollutant because it comes from a variety of sources: cropland, pasture, urban/suburban settings, construction sites, and sanitary landfills. The texture of the soil, its potential for absorbing water, the amount of time it is exposed to water, the steepness and length of the slope, and the amount of protective cover on the soil are all factors influencing the extent of erosion. Disturbed land erodes more easily than land in a natural condition. A muddy, sediment polluted river is an all too common sight in Louisiana.
Sediment as a pollutant is harmful by itself and is even more so when combined with pesticides, fertilizers or animal waste. Sediment pollution can cause serious ecological and physical damage to streams, rivers, ponds, lakes, and estuaries, as well as cost us all through taxes and lost revenue.
Erosion Erosion is a natural process. Some erosion is inevitable and cannot be stopped. However, urban development that disturbs soil and vegetative cover results in an unnatural acceleration of the process and can cause water quality problems, local area flooding, and increased maintenance costs. Erosion degrades water quality when pollutants, such as phosphorus, bind to the soil and are carried into waterways along with runoff. Local area flooding can result from the eroded soil clogging storm drains and from sediment altering the depths of local creeks and streams. Erosion-induced flooding can cause property damage and added maintenance costs to both the property owner and the agency responsible for surface water management. Soil particles resulting from the erosion of land are carried by rainwater to streams, lakes, rivers, and bays. Phosphorous, a nutrient, attaches to sediment and is carried to streams by runoff. Sediments accumulate in waterbodies and destroy feeding grounds for aquatic life, clog fish gills, block light, and increase water temperature. Erosion Hurts Streams Sediment pollution of streams and reservoirs reduces their volume capacity and increases the expense municipalities and industries pay to treat water. Millions of dollars are spent each year dredging channels, harbors, and drainage ditches to remove excess sediment. Sediment suspended in water destroys fish and wildlife habitat. Sediment from eroding stream banks and land surfaces and agricultural and industrial chemicals carried by that sediment could smother aquatic life, clog fish gills, and cut off light to underwater plants. In addition, eroded areas may be unable to support vegetation. Sediment pollution can be just as deadly to aquatic life as cyanide or DDT. Signs of Erosion
Make a Difference
|
©
Copyright 2006 BVD. All Rights Reserved. contact webmaster
|
Sediment is by volume, the state's number one pollutant of surface waters and usually is symptomatic of erosion problems in upstream tributary watersheds. Erosion of soil by wind and water is a natural process, but sediment pollution in our local streams is usually the product of accelerated erosion, which can come from any activity involving significant earth disturbance – such as crop planting, and construction of buildings and roads. 
Farms that are managed with sound conservation plans and construction sites that use Best Management Practices (BMPs) for erosion control have a greatly reduced potential for being sources of polluted runoff. On the other hand, a summer rainstorm can remove many tons of soil from a one-acre farmfield or construction site that has inadequate erosion controls. The sediment from such sites washes into nearby streams, resulting in muddy, sediment-laden waters. Sedimentation occurs when the sediment settles to the bottom of a stream or other body of water.