Stormwater Runoff Creates Pollution Without Pipes

May 25, 2011

With spring rains and summer storms moving into the national forecast, now's a good time to think about the ways stormwater pollution may be ruining your local lakes and streams. And how to fix that.

Only a few decades ago, images of rusty pipes gushing industrial chemicals or sewage were the iconic culprit in the fight against water pollution. But those threats have been greatly diminished thanks to the 1972 Clean Water Act. That law gave EPA and the states authority to limit wastewater discharges directly into surface waters through the National Pollutant Discharge Elimination System (NPDES), which granted discharge permits only on certain strict conditions. It worked pretty well. But pollution persists in many lakes and streams.

Today, "nonpoint" sources of water pollution are what have officials worried: the pollution that doesn't come from the end of a pipe. When rain falls or snow melts, the runoff can pick up fertilizers and pesticides from agricultural fields, sediments from construction sites, engine oil from city parking lots, and germ-laden dog poop from curbside. Taken together, "nonpoint" pollutants like these are far and away the biggest threat to our water quality. In fact, they're the major reason why the EPA estimates some 40% of our rivers, lakes, and estuaries are too polluted for human consumption or use. And, since they come from nearly everywhere, nonpoint pollutants are extremely difficult to regulate, although the EPA is attempting to create new national regulations for new municipal developments to address the issue.

Unfortunately, the average American still remains unconcerned about nonpoint pollution. According to a study released in January 2011, residents in the Milwaukee, Wisconsin, area largely ignored nonpoint pollution and felt no personal responsibility for polluted waterways.

To help you cover what summer storms will carry down the streets of your beat, here are some good resources.


  • First, you might want to "Surf Your Watershed," using an online application from the EPA that shows you exactly which water bodies are impaired. Simply enter your ZIP code, and get a wealth of information from a watershed map to water quality assessment reports to citizen groups at work in the watershed.
  • Many state water quality agencies have online or publicly accessible data systems that parallel EPA's (in fact, the data usually comes from the states). Check with your state's agency or its Web site.
  • Another EPA map offers to show Nonpoint Source Pollution Programs in your area.
  • The USGS National Water Quality Assessment Data Warehouse is a good starting point to see not only the current conditions of waterways near you, but also their change over time.


Agricultural Runoff

According to the most recent National Water Quality Inventory, agricultural runoff is the "leading source of water quality impacts to surveyed rivers and lakes, the third largest source of impairments to surveyed estuaries, and also a major contributor to ground water contamination and wetlands degradation." The consequence of such runoff is well illustrated by the annual plume of nutrients that pour into Lake Erie from the Maumee River. Much of the runoff is fertilizer from the heavily farmed western Lake Erie watershed. The runoff is high in the fertilizers phosphorous and nitrogen, which leads to a gigantic algal bloom in Lake Erie that, after it dies off, sinks to the bottom and begins decomposing, depleting the water of oxygen. Every summer, a "dead zone" grows in Lake Erie as the oxygen levels get so low that fish can't survive. This is the same phenomenon observed in the Gulf of Mexico where the Mississippi dumps out sediment and fertilizers from a large swath of the U.S.

Most agricultural pollution control efforts occur at the state level, where departments of natural resources attempt to help farmers adopt voluntary best practices in tilling and irrigating their fields, grazing their animals, applying fertilizers, etc. According to a 2010 report produced by the Environmental Law and Policy Center and the Mississippi River Collaborative, these measures are failing to protect water quality, since they are not mandatory. But the farm lobby is politically powerful, and farmers have resisted mandatory controls for decades. Most of the time, the best that could be hoped for has been federal incentive payments (e.g., those under the Conservation Reserve Program) for land conservation measures that reduce pollutant runoff .

A list of general agricultural issues and guidelines from the EPA is available here.

More detailed information on how farmers can mitigate their environmental impacts is available through the USDA's Natural Resources Conservation Service website. You can dig through this site for more technical papers on topics like the "Fate and Transport of Nutrients: Phosphorus" and any other related runoff issues and solutions.

To access your own state's agricultural runoff policies, you'll need to first contact its department of natural resources. A list is available here.

Urban Stormwater Runoff

Another of the main contributors to nonpoint pollution is the outdated infrastructure of metropolitan areas. Especially in cities in the Northeast and Great Lakes regions, turn-of-the-century water management systems divert rain water from impervious surfaces like roads and parking lots and into storm sewers. Often times, these empty directly into the nearest river, lake or estuary. Updated versions of storm sewers send these waters to wastewater treatment facilities. However, during intense rain events, so much water gets diverted that the wastewater facilities can't handle the flow. The result is a "combined sewer overflow," which means sewage and storm water mix and, while some ends up in the treatment facility, most is discharged straight into the storm water canals and, eventually, into nearby bodies of water.

Urban runoff is a chief culprit in polluting streams and estuaries. The Chesapeake Bay, surrounded by exploding suburban development, offers one example of the damage such nonpoint pollution can cause. In fact, it has its own federal-state program. Unlike agricultural runoff, however, the US EPA has stronger regulations for urban runoff. In fact, phase II of the National Pollutant Discharge Elimination System aims to combat point source pollution and is used as a regulatory tool to manage stormwater systems of U.S. cities as the discharge from municipal stormwater systems is considered a "point" source of pollution even though the pollutants being discharged are concentrated into the storm sewers after being collected from all over the surrounding area. A list of "best management practices" for urban runoff can be found here.

In the end, though, urban runoff is a problem to be addressed at the local level, and that means local stories. It's about planning and zoning boards, ordinances passed by city or county councils, enforcement by local authorities — and very often local funding mechanisms.

There are also a couple of more detailed reports, one from the EPA entitled "National Management Measures to Control Nonpoint Source Pollution from Urban Areas" and another released in 2008 by the National Research Council called "Urban Stormwater Management in the United States."

A good introductory fact sheet on urban runoff is available from the University of Wisconsin-Extension. And The Chesapeake Bay Foundation offers its take on water pollution in the bay.

Construction Sites

Construction sites are often bare-dirt landscapes covered in debris from demolished buildings and other construction materials. Obviously this makes them prime vectors for nonpoint source pollution. In fact, they are such prolific producers of polluted runoff, that they're regulated under the same NPDES regulations the EPA uses for urban runoff. Any construction site encompassing more than an acre is required to obtain state permitting for their stormwater discharges. Many of the regulations involve diverting water to stormwater systems and installing fences and other barriers for erosion control.

This EPA web page offers basic information on construction runoff.