Protecting Public Health and the Environment.

Nonpoint Source Pollution

Unlike polluted water that is discharged directly from a pipe (point source) into surface waters, nonpoint source (NPS) pollution comes from many diffuse sources. It generally does not have a single point of origin. NPS pollutants can be natural, such as sediment, or human-made, such as chemicals and toxics. They are generally found in or on the land and carried off by stormwater runoff when it rains or snowpack melt. Runoff picks up and carries away the pollutants, finally depositing them into nearby surface waters or by leaching into ground water. Contaminated ground water is a significant concern because more than 95 percent of Idaho's drinking water comes from ground water.

Sometimes NPS pollution can be traced to several sources. The following are common NPS pollutants and their sources:

  • Chemicals and soaps from driveways and roofs
  • Fertilizers and pesticides from agricultural lands and urban areas such as yards, parks, and golf courses
  • Oil, antifreeze, and other toxic materials from roadways
  • Sediment from improperly managed construction sites and crop and forestlands
  • Salts from irrigation ponds and acid drainage from abandoned mines
  • Bacteria and nutrients from livestock and pet wastes and faulty septic systems

Idaho's Nonpoint Source Management Program

DEQ's nonpoint source program was created in 1989. Since then it has ambitiously pursued its implementation, dedicating the personnel and funding needed to advance its efforts in nonpoint source water pollution control activities. Learn more.

Impacts of Nonpoint Source Pollution

Nonpoint source pollution can have varying impacts on the environment. It can harm fish, wildlife, and their habitat; promote excessive weed growth in surface water bodies; generate odors; and otherwise degrade Idaho's scenic beauty. For example, fish habitat is negatively impacted when sediment settles out in streams, lakes, and wetlands, covering up habitat for microinvertabrates and fish. Fish can be stressed and killed in nutrient-enriched waters as dissolved oxygen is depleted by the excessive plant growth that results. Thick beds of algae can use up oxygen and block out sunlight to aquatic life below, further impairing the beneficial uses (such as swimming and fishing) of Idaho waters.

Prevention of Nonpoint Source Pollution

We must all work together to prevent or reduce the negative impacts resulting from NPS pollution. All branches of government, federal, state and local, as well as private individuals and businesses must work together.

§319 Subgrants in Idaho

Section 319 of the Clean Water Act established a program under which states, territories, and tribes may receive funds to support a wide range of activities, including technical assistance, financial assistance, education, training, technology transfer, research, and monitoring. These funds may also be used to support specific NPS implementation projects. DEQ is the agency responsible for administering the §319 grant program in Idaho. DEQ awards subgrants annually, on a competitive basis, to parties who wish to take action to correct problems caused by nonpoint source pollution.

Staff Contacts

Nonpoint Source §319 Coordinator
Julia Achabal
DEQ State Office
Water Quality Division
1410 N. Hilton
Boise, ID 83706
(208) 373-0321

More Information

Polluted Runoff (Nonpoint Source Pollution)

Related Pages

Nonpoint Source Management §319 Subgrants

Pollution Prevention for Citizens

How Your Community Can Prevent Pollution