Soil particles can become suspended in the water as a result of erosion in streams or on beaches, or from wave-induced resuspension of particles from the bottom. Not only is the resulting muddy water unaesthetic, but also is a threat to living organisms. As described above for phytoplankton, SAV growth is blocked due to the greatly diminished sunlight reaching its leaves.
There is a spectrum of different sized particles in soil, and the smaller particles take longer to settle out and can become transported some distance from their origin. The sediment also sometimes causes problems when it settles out.
Organisms such as oysters, which get food by filtering the water, become stressed by the inedible soil particles, which must be segregated from the food particles. If deposition of sediment continues, oysters become buried and die. In addition to the negative impacts on living organisms, siltation fills in previously deeper boating areas, particularly at the heads of tributaries. This has led to the abandonment of some community piers in the Severn.
Response: Stormwater management needs to be improved to prevent stream erosion during storm events. The Severn River Commission has strongly supported adoption of the new Maryland Stormwater Guidelines into Anne Arundel County's codes to be adopted by the County Council during the summer of 2001. Although these more stringent requirements for stormwater management will minimize the further loading of sediment by future development, much remains to be done to repair damage done to streams by existing development. The Commission has been actively involved in the design of the Severn River Stormwater Management Master Plan, which will prioritize degraded streams for restoration.