Stream Crossings
Legal Requirements


  • The Stream Channel Protection Act of 1971 (Tide 42, Chapter 38, Idaho Code) requires that a permit be obtained from the Idaho Department of Water Resources (IDWR) for any alterations within the beds and banks of continuously flowing natural streams in Idaho.

  • Before any work starts, the party intending to alter a stream channel must complete a Joint Application form for use by the Idaho Department of Water Resources, and, where needed, the Department of Lands and the U.S. Army Corps of Engineers.

  • IDWR routes applications to the other agencies, when needed, and issues the permit.

  • Permanent or temporary stream crossing structures, fords, riprapping, or other bank stabilization measures and culvert installations are usually forestry-related projects subject to Stream Channel Protection Act permits.

  • The joint application requires information including the location, description, and project plans. The evaluation may include an on-site review. Larger, more complex projects may require more than 60 days before IDWR can issue or deny a permit.

  • Concrete planks, fastened together and stretched across the streambed provide an improved ford crossing. Approximate cost: $100 per running foot Installed.
    Limited traffic on this improved ford crossing has minimal impact on the streambed and on sediment production.


    Streams can be crossed with culverts, bridges or fords. Culverts are the most common stream crossing structure. Bridges are best for large streams and areas plagued with floatable debris problems. Bridges also have less effect on fisheries than other methods. Fords are often less desirable because of continued disturbance to the streambed. Choice of the stream crossing method depends on the following:
  • Stream size
  • Cost of construction and maintenance
  • Amount of road use and years of use
  • How the road approach lies with respect to the stream
  • Soil foundation conditions
  • Available equipment and materials
  • Permit requirements

  • A wrong choice of stream crossing method can result in major damage to both the immediate site and down-stream water uses. That is why strict forest practice requirements govern stream crossings. In addition, all landowners considering temporary or permanent stream crossings on perennial streams must obtain a stream channel alteration permit from the IDWR.


    Never allow a ditch to drain Into a stream. Drain road ditches into vegetated area far enough from the stream that there is no chance of ditch sediment reaching the stream channel.

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