This week, American Rivers, a national organization dedicated to the protection and restoration of the nation’s rivers and streams, released a report listing the country’s ten most endangered waterways. Topping the list is the Potomac. It’s a wakeup call that we must do more to protect our nation’s waterways, particularly Potomac River.

The Potomac River, known as the “nation’s river,” is a vital resource for the tourism and fishing industries, outdoor enthusiasts and the five million people who depend on it for drinking water. Running 380 miles through Virginia, Washington DC, Maryland, West Virginia and Pennsylvania, the Potomac has suffered from decades of urban, suburban and agricultural runoff.

The Potomac River feeds into the Chesapeake Bay, joining the health of the two waterways. Actions undertaken through the Clean Water Act of 1972 have proven successful. In particular, upgrades to water treatment facilities have dramatically reduced the incidence of water-borne diseases and enabled some aquatic species to return to healthy levels. To build on these improvements, the Environmental Protection Agency (EPA) must expand these fixes all along the watershed. This progress, however, threatens to be overwhelmed by population growth and consolidations and growth in the agricultural sector.

With this growth comes an accompanying increase in human waste and construction of impervious surfaces like asphalt and concrete. The consolidation and expansion of unregulated poultry and livestock has overwhelmed previously successful voluntary commitments by traditional farmers to reduce nutrient and sediment runoff. These changes threaten to offset gains made through better land use decisions and upgraded treatment plants.

Those who live close to the Potomac in Northern Virginia have seen massive fish kills and the loss of aquatic life. They know firsthand that the river is stressed. For example, we learned just a few years ago that up to 100 percent of the male smallmouth bass pulled from the Potomac have both female and male reproductive organs. Scientists believe this abnormal development is the likely the result of synthetic chemicals from human and animal waste or pesticides contaminating the Potomac and its tributaries.

President Obama has requested $72.6 million to carry out EPA’s Chesapeake Bay cleanup programs, a $15 million increase over the current year’s budget. But Republican opposition in Congress may actually cut funding for the programs, and further, they are pushing legislation to roll back federal authority under the Clean Water Act to fix these problems. Ground zero in the debate is whether EPA will be able to establish pollution limits on a watershed by watershed basis that will include limits on all major sources of nutrients and sediment polluting the Potomac. At stake, as Bob Irvin, President of American Rivers, says is that “if Congress slashes clean water protections, more Americans will be sick and communities and businesses will suffer.”

As Ranking Member on the House Interior & Environment Appropriations Subcommittee, I will continue working to ensure that the EPA has the resources to protect our nation’s drinking water and fight efforts to undo the progress we have made on the Potomac and the Chesapeake Bay.

Rep. James Moran (D) is Virginia’s 8th Congressional District Representative in the U.S. House of Representatives.