One of the impairments listed for the Rock River is turbidity, also known as cloudiness of water or sediment laden water.  Causes of turbidity can be storm water run off, soil erosion, failing septic systems, algal growth and stream bank erosion.  Over the past eight years a new method of stream bank stabilization has been implemented on seven stream bank projects on the Rock River.  Known as J-Hook weirs, these structures slow the flow of water while directing the energy of the water toward the middle of the stream.  J-Hooks are a natural, effective and less expensive method to control stream bank erosion.