Protecting Public Health and the Environment.

Idaho Environmental Guide for Local Governments: Surface Water

Surface water is all water that is naturally open to the atmosphere, such as lakes, rivers, streams, and reservoirs.

Why Communties Should Care

Under the Clean Water Act, DEQ establishes and the U.S. Environmental Protection Agency (EPA) approves total maximum daily loads (TMDLs) for pollutants in impaired assessed water bodies. These loads become incorporated into federal discharge permits.

Under Idaho's Water Quality Standards, cities and counties cannot discharge materials to surface water or degrade surface water quality without first obtaining a permit, if required.

Surface water pollution can result from a number of sources, including dredging, stormwater runoff, and industrial or municipal wastewater discharges.

Cities and counties manage land use and are responsible for determining how land is developed and zoned and for protecting the features of surface water through city and county ordinances.

What Communities Can Do

  • Prior to project approval, request that project information specify which requirements under Idaho's Water Quality Standards apply.
  • Understand the proximity of all surface waters to a project and how the project could cause surface water pollution (due to dust, stormwater runoff, etc.). Consider surface water protection into consideration for all projects.
  • Make sure projects have acquired appropriate surface water permits prior to approval. Under the federal Clean Water Act, any in-water construction discharges of pollutants into surface waters must have an Army Corps Section 404 permit or a National Pollutant Discharge Elimination System (NPDES) permit from EPA.
  • Plan ahead by preventing stormwater pollution.
    • Develop stormwater ordinances.
    • When approving development plans, consider sustainability by taking into account water quality issues.
    • Participate in watershed advisory groups and development of water quality improvement plans.
    • Implement land use regulations or ordinances, especially for activities located near surface water.
    • Incorporate pollution prevention strategies into the land use and planning process, such as protecting surface waters by using buffers or other protection measures.
    • Support a used oil or household hazardous waste collection program.
    • Join the Storm Drain Marking Program.
  • Local governments have authority to implement ordinances that help prevent stormwater pollution beyond federal and state laws and regulations. Determine what is best for the health and welfare of the community.

Total Maximum Daily Load (TMDL)

Under the Clean Water Act, DEQ establishes and EPA approves TMDLs for pollutants in impaired water bodies. Simply put, a TMDL is a pollutant budget. A TMDL is a calculation of the maximum amount of a pollutant that a water body can receive from human-caused sources and still meet water quality standards.

  • Determine if a water body near a project has a TMDL; if so, additional considerations may be advisable for such projects. Contact DEQ for more information.
  • Plan ahead by developing a One Plan or a Natural Resources Conservation Service Conservation Plan. Such a plan will include recommended practices for minimizing water quality impacts, based on the specific conditions in the area.