Best Management Practices (BMPs) for silvicultural operations, in most states, represent the minimum standards necessary for protecting and maintaining the water quality as well as some wildlife habitat values while conducting forestry activities. BMPs try to create a balance between overall natural resource protection and use. Many states go beyond these standards suggested by the federal government.
Most state BMP programs were developed in the late 1970's and early 1980's as required by the Federal Water Pollution Control Act . That act mandated states to develop "a program to protect and improve the physical, chemical, and biological integrity of the nation's waters so they remain "fishable" and "swimmable" for present and future generations." Most states have now refined their water quality regulations and BMPs to reflect the latest federal, state, and local requirements.
A new site called Water Quality and BMP's for Loggers gives an excellent report on state requirements and issues pertaining to forestry's effect on water quality. I have compiled a state by state list from this site, of information and contacts you can use to find out about your local situation.
Water Quality Info By State

