Sources of nonpoint source pollution are many, but agriculture is often identified as a significant source.  Because agriculture requires many acres, its potential impact on water quality is great.  The Lightwood Knot Creek in Covington County, Alabama , was a seven-year study to demonstrate improvements in the quality of surface water in selected subwatesheds that occurred as a result of implementing appropriate BMPs.

Cooperating partners were: Geological Survey of Alabama (GSA), Natural Resources Conservation Service (NRCS), landowners, Alabama Department of Environmental Management (ADEM), Environmental Protection Agency (EPA).  GSA applied for a grant to participate in the National Monitoring Program on Lightwood Knot in Covington County, Alabama .  The grant was funded by EPA with Clean Water Act, Section 319 which provides demonstration funds in cooperation with ADEM.

Primary contaminants identified during the pre-treatment phase were excessive sedimentation, large nutrient loads (primarily nitrate), and excessive bacteria.

 NRCS identified BMPs to address impaired water quality issues.  Implemented BMPs included 13 actions that changed the cattle feeding practices, limited cattle access to streams, changed the method of dead bird disposal, changed the method of poultry litter storage, and controlled erosion.

 Once BMPs were installed, data were analyzed to determine the extent of change.  Post-BMP analysis continued for three years.

 Interpretation of analytical data collected from April 1996 – September 2002 indicates that stream water quality may be improved significantly by evaluating the sources and magnitudes of impairments and implementing appropriate BMPs to address nonpoint source pollution.  Using paired monitoring design and statistical tests (T-test and Regression) produced data that indicates that installation of best management practices do indeed have a positive impact on water quality.  Results from the regression statistical analyses indicate a 92 percent reduction in bedload sediment, 71 percent reduction in nitrate, and an 11 percent reduction in fecal coliform bacteria in the study area.  In the controlled watershed where nothing was done, the post-date are very similar to the pre-data.