“The bottom line is that both polluted runoff and its management are likely to affect you and your community in the near future.”


California Coastal Commission

Mission Resource Conservation District

State Water Resources Control Board

Local Government Commission

Department of Water Resources

National Oceanic and Atmospheric Administration

UC and USC Sea Grant


Linking Land Use to Water Quality


For more information, contact the CA NEMO Partnership:

Cynthia Mallett
Mission RCD
990 E. Mission Road
P.O. Box 1777
Fallbrook, CA 92088-1777


(760) 728-0342

(760) 723-5316


The California NEMO Partnership is an educational program for land use decision makers that addresses the relationship of land use to natural resource protection.

© The University of Connecticut. Adapted with permission of the University of Connecticut Cooperative Extension System.


What is Nonpoint Source Pollution?
Nonpoint source pollution is a fancy term for polluted runoff. Water washing over the land – whether from rain, car washing or the watering of crops or lawns – picks up an array of contaminants, including oil and sediment from roadways, agricultural chemicals from farmlands, and nutrients and toxic materials from urban and suburban areas. This polluted runoff finds its way into our waterways, either directly or through storm drain collection systems.

The term nonpoint is used to distinguish this type of pollution from point source pollution, which comes from specific sources such as sewage treatment plants, industrial facilities or municipal storm drain systems. Scientific evidence shows that although huge strides have been made in cleaning up major point sources of pollution, our precious water resources are still threatened by the effects of polluted runoff. In fact, the Environmental Protection Agency has estimated that nonpoint source pollution is now the single largest cause of the deterioration of our nation’s water quality.

Whatever They Call It, Why Should I Care About It?
The effects of polluted runoff are not limited to large lakes or coastal bays. In fact, chances are that you don’t have to look any farther than your neighborhood stream or lake. Water pollution in your community, and perhaps in your own backyard, can result in anything from trash-filled creeks, to beach closures, to contaminated drinking water and coastal waters. There’s not much chance that you can ignore this problem, even if you want to. Concern over polluted runoff has resulted in an ever-increasing number of state and federal laws enacted over the last five years. At the federal level, a permit program for stormwater discharges from certain municipalities and businesses is now underway, and coastal zone management authorities have added nonpoint source control to their existing programs. In addition to implementing these federal programs, many states have passed laws changing local land use processes (planning and zoning) and building codes to address the problem of polluted runoff. The bottom line is that both polluted runoff and its management are likely to affect you and your community in the near future.

What Causes Polluted Runoff?
You do. We all do. Polluted runoff is the cumulative result of our everyday personal actions and our local land use policies. Here’s a brief rundown on the causes and effects of the major types of pollutants carried by runoff.

Pathogens: Pathogens are disease-causing microorganisms, such as bacteria and viruses, which come from the fecal waste of humans and animals, and from other organic matter. Exposure to pathogens, either from direct contact with water or through ingestion of contaminated shellfish, can cause a number of health problems. Because of this, bathing beaches and shellfish beds are closed to the public when testing reveals significant pathogen levels. Pathogens are deposited on the land through feces from animals, and can also enter our waterways from improperly functioning septic tanks, leaky sewer lines and boat sanitary disposal systems.

Nutrients: Nutrients are compounds that stimulate plant growth, such as nitrogen and phosphorous. Under normal conditions, nutrients are beneficial and necessary, but in high concentrations they can become an environmental threat. One form of nitrogen found in drinking water can cause health problems, including “blue baby” syndrome. Over-fertilization of estuaries, bays, and lakes by nutrients can lead to massive algal blooms, the decay of which can create odors and rob the waters of life-sustaining dissolved oxygen. Nutrients in polluted runoff can come from agricultural fertilizers, septic systems, faulty sewer systems, home lawn care products, and yard and animal wastes.

Sediment: Sand, dirt, and gravel eroded by runoff usually ends up in stream beds, bays, or shallow coastal areas, where it can alter stream flow and decrease the availability of healthy aquatic habitat. Poorly protected construction sites, agricultural fields, landscaped areas, cleared forests, and roadways can be major sources of sediment. In addition, toxic contaminants bind to sediment and be transported to waterways by runoff.

Toxic Contaminants: Toxic contaminants are substances that can harm the health of aquatic life or human beings. Toxins are created by a wide variety of human practices and products, and include heavy metals, pesticides, and organic compounds such as PCBs. Oil, grease, and gasoline from roadways; chemicals used in homes, gardens, yards, and on farm crops; and air emissions from industries and vehicles are all major sources of toxic contaminants.

Many toxins are very resistant to breaking down, and tend to remain in the environment, or pass through the food chain to concentrate in top predators. For example, public health warnings on the hazards of eating certain fish are due to the environmental toxins that accumulate to levels of concern in fish.

Debris: Trash is without a doubt the simplest type of pollution to understand. It interferes with enjoyment of our water resources, and many types (such as plastic and Styrofoam), can be a health threat to wildlife. Typically, this debris starts as street litter that is carried by runoff down storm drains into our waterways.

Small-sized debris, such as cigarette filters, can be mistaken for food by fish, birds, and other wildlife. Consuming bits of plastic and other garbage can cause illness and death in wildlife. Larger-sized debris, such as plastic retaining rings for sodas, can ensnare, entangle and kill wildlife as well. Some debris will also leach toxic chemicals into the water.

What Can I Do About All This?
First of all, you can begin to clean up your own act. There are many good publications and programs ( that can help you do simple but important things, such as conserve water, dispose of hazardous waste properly, and garden in a cost-effective, environmentally responsible manner. See the CA NEMO Fact Sheet #1a for a list of resources.

As you can see, polluted runoff is largely the result of the way we develop, use, and maintain our land. Land use policy decisions are mostly made at the municipal level, through the actions of elected officials and local planning and zoning commissions. There are many techniques and regulations that can greatly reduce the effects of polluted runoff, and there are more being developed every day. The rest of this fact sheet series is devoted to telling you about your options. If you’re on a local commission, learn a little more about polluted runoff and how you can combat it in the course of your everyday decisions. If you’re not on a commission, ask your friends and neighbors what they are doing about polluted runoff.





The California NEMO Partnership is a charter member of the National NEMO Network.