Traditional images of water pollution often consist of a pipe spewing industrial contaminants into a river. The Clean Water Act helped solve many of Ohio's traditional pollution problems. Remaining problems are more challenging and may be traced to two kinds of pollutants: polluted run off and physical alterations to a stream or river channel. These are referred to as nonpoint sources of pollution since they are the result of a land use and/or man-made changes to a river rather than flowing from a single point of discharge.
Polluted run off is rain or snow melt flowing across the land picking up contaminants such as sediment, nutrients or bacteria, carrying these pollutants to small streams that eventually flow into a larger river. Physical alterations are changes made to a stream channel or stream banks and include activities such as the conversion of headwater streams into drainage ditches, constructing levees and dams, and straightening a stream to encourage improved drainage. Physical alterations also include activities such as removing trees along a river bank or installing rock rip-rap on a river bank to prevent erosion.
The primary causes of nonpoint source impairment in Ohio streams are habitat alteration, hydro-modification to stream channels, sediment and excessive nutrients. Streams in agricultural areas of Ohio appear most frequently to be impaired by physical alterations, such as ditching, and impairments caused from excessive sediment and nutrients. Streams in urban and rapidly developing residential areas of the state are further impaired by nonpoint causes such as lowhead dams and nonpoint source contaminants carried off land surfaces by increased storm water runoff. In the coalfield regions of southeastern Ohio, another cause of impairment is abandoned mine drainage, which has impaired more than 1,300 miles of streams in the region.
Fortunately, management practices to address nonpoint source pollution are becoming more effective. Previous efforts to address these types of problems often consisted of implementing demonstration practices and trying new techniques for managing the ubiquitous nature of nonpoint source pollutants. Years of trial and error are resulting in a much broader understanding of management practices needed to restore impaired waters and improve water quality.
Physical alterations may be addressed using restoration practices such as removing lowhead dams, eliminating or modifying levees and restoring floodplains and riparian forest cover. Headwater streams previously converted into drainage ditches are effectively being restored using natural stream channel design techniques. Polluted run-off is being more effectively reduced using pollution prevention practices such as replacing failing home sewage treatment systems, installing riparian filter strips and controlled drainage systems or restoring ditches to 2-stage channels to allow for more natural stream function. Many other practices designed to slow the flow of nutrients from croplands, and sediment from mining sites and construction sites are also available to improve the health of Ohio's rivers and streams.