Dams and Dam Safety

new london dam

Dams are an important part of the infrastructure of Minnesota. They maintain lake levels and impound water for flood control, power production and water supply.

There are more than 1,250 dams in Minnesota; 800 are public dams, and the state owns over 430 of the public dams. Most of the public dams are more than 50 years old and require ongoing or emergency repairs and reconstruction to maintain their structural integrity. Through state bonding, the DNR spends approximately $1 million annually on repairs and reconstruction. An estimated $114 million is needed over the next 20 years to assure public dams remain in a safe and usable condition.

Dams fail due to improper operation, inadequate maintenance and design and unusually large floods.

Dam Safety Permits

Permits are required to build a new dam; alter, repair, or remove an existing dam; modify dam operations; perform major maintenance; or transfer dam ownership. Plans for construction must be completed by a professional engineer experienced in dam engineering. Application and inspection fees may apply.

Dam Owners

Dam owners must properly maintain, repair, and operate their dams. They may also be required to make improvements to meet current dam safety criteria. If development downstream raises the hazard classification of the dam, the owner may be required to bring the dam into compliance with the higher standards required under the new classification. The owner of the dam could be found liable for damages incurred from dam failure or improper operation, particularly if the dam is not compliant with state standards. The DNR repairs and maintains state-owned dams.

Construction and operation of a dam can have varied impacts to surrounding lands and the environment. Losses suffered by other parties can become liabilities to a dam owner. Impacts could include:

  • altered ground water levels that affect wells or crops
  • increased flooding caused by improper operation
  • injuries to anglers, boaters or swimmers because of hazardous conditions at the dam
  • environmental damages including degraded water quality, alteration of sediment transport, increased erosion, loss of aquatic habitat, and altered stream biology.

Find a dam owner

The DNR maintains data on Minnesota dams that are included in the National Inventory of Dams (NID) database. This includes the dam name, location, owner, purpose, hazard classification, structural condition, and about 50 additional data elements.