Oct. 18 marks the 40th anniversary of the Clean Water Act, a crucial law that protects the nation's water from pollution. Congress passed the landmark legislation at a time when much of our water was so contaminated by industrial waste and other pollutants that it was unfit for public use. By setting ambitious goals for the cleanup of contaminated waters, the Clean Water Act led to dramatic improvements in water quality and serious reductions in industrial pollution. As we celebrate the significant successes of the Clean Water Act, however, we must remain focused on responding to current and future threats to water quality.