Rutgers New Jersey Agricultural Experiment Station | [Cooperative Extension of Salem County]

Preventing Water Pollution for Homeowners


  1. What is a watershed?
  2. The water cycle
  3. Pollutants in surface waters
  4. How to prevent pollution: good management practices
  5. Helpful links

What is a watershed?

A watershed is an area of land that drains to a specific stream, river, or lake. The limits of a watershed vary with scale: smaller watersheds are nested within larger watersheds. The Delaware River Basin includes parts of New York, Pennsylvania, New Jersey, and Delaware, but within this large watershed are many smaller watersheds draining to more local streams, rivers, and creeks. And those streams in turn flow into larger rivers that may flow to the Delaware River.

The water cycle

Infiltration is the process
of water moving into the
soil. During infiltration, the
soil is essentially absorbing
the rain, irrigation water,
or snowmelt.

An impervious surface
is one that cannot
infiltrate water. Common
impervious surfaces include
roofs, driveways, and very
compacted soils.

Water that is delivered to the watershed as precipitation can follow different paths as it makes its way to a local stream. Some precipitation water will infiltrate into the soil, where it might make its way to shallow groundwater and then move laterally slowly in the soil to maintain the base flow of a local stream. Infiltrated water can make its way to deeper groundwater, where it might later be pumped for drinking water or irrigation.

If precipitation or irrigation falls too quickly to infiltrate into the soil or falls upon impervious services like roofs or driveways, water can move overland as surface runoff. Surface runoff moves quickly to local rivers across the land and through storm drains, exacerbating downstream flooding. Surface runoff is also a concern because it can pick up potential pollutants and deliver them to streams and lakes. Depending on the weather and land use in the watershed, a significant portion of rain or irrigation applied to the land in a watershed may be returned to the atmosphere through transpiration by plants and evaporation from soil and other surfaces.

A simplified water cycle.


Pollutants in surface water

Many natural and human activities have the potential for polluting rivers, lakes, and groundwaters. Point sources of pollution are those where there is an identifiable single point of pollution, such as a factory with a smoke stack or a wastewater treatment plant with a discharge pipe. In contrast, non-point sources of pollution are those which are more dispersed over the landscape, including agriculture, rural or suburban residential development, wildlife, domestic animals, and soil erosion.

A variety of pollutants can be contributed by residential areas, including nutrients (fertilizers), pesticides, sediment from eroded soils, and bacteria. Pollutants include nitrogen and phosphorus from lawn fertilizers, bacteria from pet wastes or the wastes of wild animals, malfunctioning septic systems, metals from deposition on roofs, pesticides applied to homes and lawns, and motor oil and other fluids from leaking automobiles. Each of these has the potential for negative impacts on surface water or groundwater for a variety of desirable water uses including drinking, recreation, and wildlife habitat. While these pollutants can travel with surface runoff, certain pollutants can also move readily with infiltrating water to groundwater. Notably, pollutants that can infiltrate into groundwater  include nitrogen in the form of nitrate and certain herbicides.


Excessive algae or vegetation in a lake may be indicators that the lake has been impacted by pollution with nutrients, usually phosphorus. Such impacts can deplete oxygen in the water, killing fish, and make water bodies less enjoyable for swimming and boating.
Large populations of Canada geese may be contributing to phosphorus and bacteria elevation in local lakes and rivers.


How to prevent pollution: good management practices

The potential for pollution from your property can be minimized by employing good management practices, including the following:

  • Use soil tests to avoid excess fertilization of lawns and gardens.  Minimize pesticide use outdoors, and water judiciously.

  • Collect roof runoff with a rain barrel, and collect runoff from roofs and lawns in a rain garden.  The goal is to keep most stormwater runoff on your property and out of storm drains. Allow water to infiltrate into the soil and not run off your property.

  • Clean up pet wastes, and don't put yard wastes into storm drains.

  • Use vegetation, mulch, or gravel to keep soil in place so it doesn't erode. 

  • Have your septic tank inspected every three to five years.  Be concerned if there is a smell of sewage or wetness or lush grass around your leach field.

  • If you have a pond or stream on your property, leave natural vegetation around the water, and use plantings to discourage geese.

A rain garden at the Holy Nativity Lutheran Church in Wenonah, NJ.  Runoff  drains to the garden which is planted with water-tolerant plants. The water slowly infiltrates into soil, allowing pollutants to be removed by plants and microbes.  Photo: Christine Boyajian, Rutgers Cooperative Extension Water Resources Program.

Helpful links

A Homeowner's Guide to Septic Systems  [link exits rutgers]

Rain barrels

Rain gardens

Stormwater management for your backyard