G1848

Stormwater Management:
Water Pollution and Our Own Yards

This NebGuide describes practices to reduce water pollution and conserve water resources by reducing the amount of pollutants and runoff water that leave a property. This is part of a series.


Kelly A. Feehan, Extension Educator
David P. Shelton, Extension Agricultural Engineer
Steven R. Tonn, Extension Educator


Homeowners preventing runoff pollution out of the street or storm drains.
Figure 1. Homeowners can help prevent runoff pollution by keeping contaminants such as oil, pesticides and other wastes, as well as excess irrigation water, out of the street or storm drain, from which runoff water is discharged directly into surface water. (Source: Environmental Protection Agency)

Protection of water quality is an environmental issue everyone faces. When it rains and as snow melts, water runs across and off our property. This runoff water is referred to as stormwater. As stormwater flows across surfaces, it picks up pollutants in its path and eventually deposits them into streams, rivers, ponds, lakes, or other surface water.

It is through stormwater that many pollutants such as sediment, nutrients, bacteria, heavy metals, and others reach surface water. This is called nonpoint source pollution. It cannot be easily traced to one source or one property. Rather, small amounts from many sources and many properties eventually accumulate to amounts that impair water resources.

Nonpoint source pollution is one of the leading causes of water quality degradation. It results in impaired drinking water, excess algal growth, fish kills, decreased aesthetics, reduced recreation and tourism, and more. It is environmentally and economically costly. Virtually everyone contributes to nonpoint source pollution and every homeowner can do something to help reduce it.

Where Does Stormwater Go?

Every property drains to a waterway of some type, regardless of whether the property is located near surface water or not. In urban areas, rainwater runs across rooftops, paved areas, and yards, and is directed to storm drains. In most municipalities, stormwater is discharged into surface water and is not treated to remove pollutants. The same is true of non-stormwater discharges such as improper connections to the drainage system or illegal dumping.

While the amount of pollutants originating from a single residential lot is small (Figure 1), these pollutants combine with pollutants from other lots and from municipal and business properties. Streams, rivers, and lakes are interconnected. Once pollutants reach a waterway, the pollution from one town combines with pollution from other cities, towns, rural areas, and so on. Everyone lives in a watershed, that area of land that drains to a specific body of water, and everyday actions affect water quality in watersheds.

Pollution from Residential Property

Many pollutants can leave residential properties in runoff: sediment, nutrients, chemicals, pathogens, vehicle-related waste, heavy metals, and more (Table I). Whether these materials pollute water or not depends on how their use, storage, and disposal are managed; and how property is designed and managed, especially lawns, landscapes, and impermeable surfaces.

Table I. Common stormwater pollutants and their sources.
Pollutant Common Sources
Sediment (sand, silt, clay particles) Bare spots in lawns and gardens, construction sites, streambank erosion, sloping areas, farm fields, wastewater from washing vehicles
Nutrients (nitrogen, phosphorous, others) Over-application or spilled fertilizer, pet waste, livestock manure, grass clippings, leaves
Pesticides Over-application or spilled material, leaks, sprayer wash-out
Disease-causing Organisms (bacteria, viruses) Pet waste, livestock manure, garbage
Hydrocarbons Engine exhaust, fuel and oil spills and leaks, vehicle tire wear, burning plastics
Metals Vehicle brake and tire wear, engine exhaust, metal gutters and downspouts, scrap piles

Environmental Benefits of Lawns and Landscapes

Lawns and landscapes can be a source of pollution, but well-designed and properly managed landscapes minimize pollution potential as well as provide many benefits.

Planted areas — greenspace — protect the environment by stabilizing soil to reduce soil erosion, slowing and reducing runoff, filtering pollutants, and cooling the air. When rain falls on greenspace, the amount of runoff water is reduced through natural retention. Rainwater soaks into planted areas where plant roots, the soil structure, and soil microbes filter many pollutants before they reach surface or groundwater. Increased infiltration helps replenish groundwater resources. Trees and shrubs cool the space around buildings, lowering energy demands. Plants absorb and remove certain air pollutants to improve air quality. Parks, natural areas, and residential landscaping increase property values, provide wildlife habitat, and increase potential for recreational activities.

Because of these many benefits, the use of greenspace to manage stormwater and reduce water pollution is on the rise. Municipalities refer to greenspace as green infrastructure that uses trees and other vegetation to manage and mitigate stormwater naturally, rather than through storm drains that discharge to surface water.

Reduce Water Pollution at Home

Pollution from runoff begins in small amounts; but can accumulate to levels that impair water quality. The opposite also can be true. The accumulated effects of individuals taking small-scale actions can have a large-scale benefit on water quality.

Homeowners can help reduce water pollution by using practices that reduce the amounts of runoff water and pollutants leaving their property. First, recognize any property is part of a larger ecosystem. Everyone lives in a watershed with all property interconnected to water, even if it is not near a stream or lake. Second, develop private sites and design landscapes with the health of the watershed in mind. Retain and/or plant more vegetated areas. Reduce the area of impermeable surfaces such as sidewalks, driveways, and patios, or consider using porous pavers or similar material. Select native and adapted plants and plant them in suitable locations for their growing requirements. Third, understand which lawn and landscape care products and management practices support sustainable landscape methods. Finally, focus on methods that reduce or slow runoff water from a property and on practices that reduce the amount of pollutants leaving a site.

Reduce and Slow Runoff Water

A lower volume of slower moving water is less likely to cause flooding and streambank or soil erosion, and will collect and carry fewer pollutants in the flowing water. To reduce the volume and velocity of runoff water leaving a property, increase the amount of pervious areas (surfaces that allow water to move into the soil such as planted areas or porous pavement); increase the number of obstacles water encounters, including shrubs and shade trees; and divert runoff water away from impervious areas onto vegetated or other pervious surfaces. Doing this will help runoff water soak into the soil for plants to use and for roots and soil to filter pollutants. This is referred to as bioretention. Following are some best management practices used to collect and temporarily hold runoff water from residential and business properties.

Keep Pollutants Out of the Path of Runoff Water

Summary

Everyone contributes to nonpoint source pollution. By using sustainable site development and appropriate landscape design principles along with best management practices, the amount of stormwater runoff and pollutants that leave properties can be reduced, thus helping to protect water quality.


Visit the University of Nebraska–Lincoln Extension Publications Web site for more publications.
Index: Water Management –Water Quality
and
Lawn and Garden – Water Management
Issued May 2008

Extension is a Division of the Institute of Agriculture and Natural Resources at the University of Nebraska–Lincoln cooperating with the Counties and the United States Department of Agriculture.

University of Nebraska–Lincoln Extension educational programs abide with the nondiscrimination policies of the University of Nebraska–Lincoln and the United States Department of Agriculture.

© 2008, The Board of Regents of the University of Nebraska on behalf of the University of Nebraska?Lincoln Extension. All rights reserved.