Market News

Big Sky River’s Act

The Big Sky Rivers Act ensures that new buildings are set back a safe distance from the banks of 10 Big Sky rivers in order to protect people and property and the rivers’ outstanding economic, biological and recreational values (see map and list of rivers on reverse side). The Act creates 250-foot wide “streamside management areas” on either side of designated rivers within which the construction of new homes and commercial buildings, or the installation of septic tanks and drainfields, is prohibited. It also limits the removal of riparian vegetation within 150 feet of designated rivers in order to minimize erosion and protect water quality.  All but one of the Big Sky rivers cross county lines. Because unwise riverside development in upstream counties can have  profound impacts on property in downstream counties, it is appropriate for the Montana Legislature to set up a consistent system of streamside protections on these large and important rivers.


  • It reduces costly flood and erosion damage by steering development away from known flood hazard areas;
  • It protects private property rights by ensuring that actions of upstream landowners do not harm downstream landowners;
  • It gives local governments control over the tools they need to manage their rivers;• It prevents water pollution from stormwater runoff, lawn chemicals, and individual wastewater systems;
  • It shields local governments from lawsuits brought by homeowners whose homes are damaged by flooding and erosion;
  • It preserves critical fish and wildlife habitat;
  • It ensures high-quality recreational opportunities for anglers and boaters who value scenery and solitude;
  • It includes a variance process to make sure no one loses the ability to build on an existing lot, and a grandfather clause to ensure that existing homes are not impacted.


  • It does NOT take away the authority of local governments to create their own streamside development standards;
  • It does NOT deprive riverfront landowners of the opportunity to build on their lots if their entire lot is located within a streamside management area;
  • It does NOT apply within incorporated cities, towns or sanitary sewer districts;
  • It does NOT prohibit property owners from rebuilding their home if it is destroyed by causes other than flooding;
  • It does NOT grant public access to private property;
  • It does NOT affect agricultural-related buildings.


Section 9 of this bill provides local control options in two important ways:

  • If local governments want to increase or decrease the size of the streamside management area on designated rivers, the legislation outlines a process for them to use. Local streamside management areas would replace the state streamside management areas in the bill.
  • If local governments want to protect streams or rivers not named in the bill, the legislation outlines a process that local governments can use—at the local government level—to establish streamside management areas.

It will be up to individual county governments to decide which staff or department can best administer designated rivers within their jurisdiction. For example, they could be administered by the county floodplain manager, health department, or planning office. If a county issues building permits, the permit could include a new section that ensures the provisions of the Big Sky Rivers Act are upheld. Or, a county could develop a permit system for buildings planned near rivers that they designated.

Please support House Bill 455.

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