Toolbox: Covering Stormwater Pollution and Control

February 29, 2012

Stormwater becomes a big media story during disasters such as floods and hurricane surges, and it's essential to cover the basics then. But there are dozens of related issues that can contribute to the disaster, and covering them in advance can help your audience understand ways of possibly preventing the peak crises.

Post-disaster coverage also is important, since a number of lessons learned may be more readily accepted while memories are fresh. In addition, there are many problems short of obvious disasters that, if addressed well and in advance, can reduce significant health and environmental problems, as well as economic damages.


Stormwater typically flows via natural processes, such as sheeting off surfaces or running through drainages such as creeks, streams, and rivers, or, in many urban settings, in underground pipes. Each type of flow can have health and environmental impacts, either in the immediate area or downstream, including the lakes, estuaries, and other coastal areas it spills into. The kinetic energy in large raindrops or scouring flows can remove soil much faster than a gentle drizzle.

One of the primary concerns for both types of flow is the substances the water picks up. Given that much of any watershed has been developed or altered in some way, rushing water can carry plenty of plain old soil, since it isn't anchored as well as it historically was. Simple sediment can alter habitat, restrict or block flows, and fill up reservoirs, reducing their function.

In many settings, that sediment may also contain contaminants such as pesticides, fertilizer, petroleum products, lead, human or animal waste, and many other harmful substances. Those contaminants can directly or indirectly kill many creatures and organisms; contribute to human health problems via ingestion, inhalation, or skin contact during freshwater or saltwater recreational activities; pollute drinking water treated at plants that aren't equipped to remove the toxics; contaminate fish that people eat; induce breathing problems for people onshore (e.g., via emissions from algal blooms that feed off excess nutrients in coastal waters), or lead to other harm.

Preventing problems related to surface flows generally involves a wide range of planning, design, construction, management, maintenance, and land use issues, often by multiple jurisdictions. Many of the same issues must be considered when solving underground pipe flows; in addition, there are complexities such as inlets, discharge points, the common practice of combining storm water flows with sewage flows, and funding.

On top of these historically well-recognized (but often poorly addressed) issues, climate change could readily exacerbate problems in some areas. A primary element of climate change is more extreme weather events, including major thunderstorms and increased rainfall intensity. The old rules of thumb about how much water will flow in any given area may go out the window, necessitating substantial changes in planning, design, and construction of many stormwater surface and subsurface systems.

Some starting points for the basics, as well as federal regulatory efforts, are:

State and local governments have a major role in this issue. Starting points for each state are:

For some information on extreme weather, see the SEJ TipSheets of:


A high percentage of US waterways that stormwater flows into remain unacceptably dirty for their intended use (such as drinking water, fishing, or recreation), leaving the country far short of meeting the 40-year-old goals of the Clean Water Act.

For instance, a 2006 report found that 42% of wadeable streams were in poor condition. An update is scheduled for December 2012.

A 2010 report on lakes, based on a limited number of criteria, found that 22% of them are in poor condition, 36% have poor lakeshore habitat, and 49% exceed the health-based limit for mercury in game fish. An update, based on sampling at 904 lakes, ponds, and reservoirs this summer in the lower 48 states, is expected in 2014.

Many estuaries, which are home to 75% of the US commercial fish catch and 80-90% of the recreational fish catch, and are a hotbed of biodiversity and the setting for many recreational activities, are in poor condition. EPA says in a 2007 report that the national average for the "poor" classification is 37%, ranging from 23% for the Southeast to 46% for the Gulf Coast and Northeast.


There are a host of issues tied to stormwater. Here are a few topics and starting points.

URBAN POLLUTION: Urbanized areas have a very complex set of stormwater problem sources and solutions. You can begin to get a handle on these with the following sources.

AGRICULTURAL POLLUTION: Farming is a major source of fertilizer, pesticides, bacteria, and other substances that can cause health and environmental problems. Altering farming practices, such as providing wider buffer zones for better runoff absorption, better targeting fertilizer and pesticide applications, diversifying crop types, or changing tilling practices, is a slow, incremental process, but many efforts have been under way for some time. You can cover this topic at the national, state, and local levels. One starting point is:

FLOODS: Areas prone to flooding are prime sources of contaminants that can be carried off by stormwater. The official delineation of a floodplain in any given area has a major impact on what is built there, or whether the area remains more natural and therefore possibly a lesser source of stormwater contamination. The assignment of a floodplain boundary is a regularly occurring and often contentious issue. Starting points for covering this include:

DEAD ZONES: Rivers routinely carry nutrients such as nitrogen into bays, other coastal waters, and the Great Lakes. In elevated concentrations, these nutrients feed organisms that thrive, then die, and then decompose. Their decomposition can lead to a sharp drop in oxygen. The resulting "dead zone" dramatically alters life in the affected area. Dead zones have become a significant problem around the globe, and one of the primary weapons for mitigating them is controlling runoff into the waterways that feed the affected waters. The concept is simple, but implementing it — which can necessitate major shifts in land use and management — has proven to be difficult. Some information that may spark ideas for your coverage, and point you toward many sources, includes:

BEACH POLLUTION: One of the most noticeable problems to people that is linked in part with contaminated stormwater — especially in areas that have combined storm and sanitary sewers — is polluted beaches. Potentially harmful bacteria in sewage are one of the frequently documented threats, but all kinds of other pollutants picked up by surface runoff or scoured out of contaminated sediment in waterways also can pose a threat. Two starting points for covering this issue are:

HARMFUL ALGAL BLOOMS: Another water contamination issue that is readily noticed, and can be a hazard to both people and the environment, is the occurrence of harmful algal blooms (HABs). These are relatively rapid growths of organisms in bays, coastal waters, and the Great Lakes that can contaminate foods such as shellfish, emit toxins that can cause respiratory problems in some people, and kill or damage some aquatic life. One of the contributing factors is nutrient-rich runoff from point and nonpoint (diffuse) sources. A few starting points for covering this include:

COASTAL POPULATION PRESSURE: Much of the US population is crammed into a fairly narrow band near coastal waters, with more than 50% of the population occupying only 17% of the nation's land. This high-density development leads to a range of impacts on associated fresh and marine waters. A starting point for delving into how to deal with these pressures is:

HURRICANE IMPACTS: Following hurricane surges and deluges, there are a range of short- and long-term impacts, such as the spread of pollutants and disease organisms on land and in near-shore areas. One example is discussed in this post-Katrina assessment of lead contamination in New Orleans, caused in part by the destruction and damage to more than 100,000 buildings that often contained lead-bearing materials.


There are many other topics to cover. For ideas, and more information, data, solutions (either engineered or more naturalistic), and other information, see:

Also see SEJ Publications: 


How to fix stormwater pollution problems depends on the situation in any given watershed and locality. Climate, terrain, water resources, infrastructure, and economics will all vary. Many ideas for solutions are discussed in the resources noted above. In addition, here's a general checklist of some things to consider if you are reporting on what can be done in your area.

PLANNING AND ZONING: One of the best ways to stop stormwater pollution is to stop it before it starts. Local planning and zoning practices make a big difference. Are your local codes up to snuff? What are the requirements for storm and sanitary sewerage for new developments? An example of one community's stormwater program is that of Lawrenceville, GA.

INLINE STORAGE: Some cities with severe stormwater problems have turned to massive and expensive public works projects to store stormwater in the pipe system that eventually carries it to the point of discharge. A commonly cited example is Chicago's Deep Tunnel Project, which will not be finished until 2029. Not all inline storage projects need to be so ambitious or difficult.

SEDIMENTATION PONDS: In many localities, new housing or mall developments have ponds which are meant to slow the runoff of stormwater and give it a chance to drop its sediment. Are such ponds required in your area? Are they regularly maintained?

AGRICULTURAL PRACTICES: Soil particles are one of the biggest nonpoint pollutants, more so because they carry fertilizers and pesticides. Since the soil conservation movement took hold in the US following the Dust Bowl, farmers have done a lot to minimize soil loss. Familiar examples are contour plowing, cover crops, and low-till methods. The US Agriculture Department has supported farmers in these efforts. Check in with your local ag extension agent.

CONSTRUCTION RUNOFF CONTROL: In developed areas, construction sites hold a large part of the disturbed soil that contributes disproportionately to stormwater pollution. Bare soil is more vulnerable to the kinetic energy of raindrops — as anyone who has seen mud running in the gutters outside a construction site knows. Simple measures like straw covers, planting, and filter barriers can help. Does your local code require them?

PERMEABLE SURFACES: Urban and developed areas often consist of a high percentage of pavement, roofs, and other impermeable surfaces. These prevent water from soaking into the ground and speed its passage to ditches and storm sewers. Replacing pavement with pavers or planted soil (or even new porous pavements) can help.  As a bonus, this may help recharge aquifers.

SEWER SEPARATION: In some urban areas — often those built long ago — sanitary sewers are combined with the pipes that carry away stormwater. During severe storms, this may mean that the volume of mixed flow overloads the sanitary treatment plant and that poorly treated — or raw — sewage gets dumped into waterways. Or, worse yet, into people's basements. Once an area is built up, separating storm and sanitary sewers gets quite expensive.  Communities unable to afford major construction costs may find ways to manage the combined sewer problem in the shorter term.

NUTRIENT CONTROL: Some of the biggest pollutants in stormwater are nitrogen and phosphorus compounds — the nutrients that promote the growth of algae and other water plants. While agriculture is a major source of nutrients, lawn and garden fertilizers may also be a locally important source. Although local ordinances may help in some cases, education of consumers in correct application methods is also key. What are your local golf courses doing with fertilizers?

PESTICIDE AND CHEMICAL CONTROL: Pesticides and chemicals in stormwater can not only harm aquatic life, but may also end up contaminating drinking water. Minimizing the use of agricultural and household pesticides and using them properly is one key step.

SYSTEM MAINTENANCE: Ever notice those catch basins (often marked by manhole covers) near the inlets in your town's storm drain system? Ever see your municipal crews cleaning them out? Regular maintenance is key to reducing polluted stormwater — and not just for storm sewers. Sediment ponds at the local shopping mall may need to be excavated, too.  Leaf collection and street-sweeping are key maintenance actions for reducing pollutants in stormwater.

POOPER SCOOPING: Stormwater from both urban and rural areas can contain significant amounts of disease-causing microbes. Proper management of manure from agricultural operations is essential. But in urban areas, dog poop can be a real issue, which is why local pooper-scooper ordinances have become more common.

TECHNOLOGICAL FIXES: There are some technological fixes that can reduce stormwater pollution — but you may need to be a sewer geek to appreciate things like swirl concentrators or catch basin inserts. Retrofitting flow restrictors into existing stormwater systems can reduce damaging peak flows. And there is always the simple rain barrel.