In middle of the 20th century, America’s rivers were in rough shape. Decades of urban growth and industrial pollution had turned many of them into dumping grounds for everything from hazardous chemicals to human waste. A burgeoning environmental movement and high profile events like the 1969 fire on the Cuyahoga River finally pushed Congress to take action. In 1972, it passed the Clean Water Act, giving the U.S. Environmental Protection Agency the authority to regulate water pollution. But which waterways the agency can regulate has been a source of conflict and confusion. In March, the U.S. Environmental Protection Agency proposed a rule it says clarifies its jurisdiction.