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. Dams are also an important consideration in assessing the health of Minnesota's watersheds.
There are more than 1,250 dams in Minnesota; 800 are public dams, and the state owns 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 unusually large floods, inadequate design, improper operation, and a lack of maintenance. When they fail, there can be a quick release of water causing rapid and unexpected flooding downstream and the possibility of significant property damage loss of life.
The purpose of the Dam Safety Program is to protect the life and safety of people in Minnesota by ensuring that dams are safe. Minnesota's program sets minimum standards for dams and regulates the design, construction, operation, repair and removal of dams. Both privately and publicly-owned dams are regulated.
The state's program was created in 1978 in response to the National Dam Safety Program Act and a series of major dam failures nationwide that killed scores of people in the 1970s.
Dam safety staff monitor, analyze, and help develop and maintain the state's dam infrastructure to protect the safety of the people of Minnesota, while working to minimize impacts on ecosystems.
Minnesota Statutes, Section 103G.515, authorize the DNR to inspect dams and issue orders directing dam owners to make necessary repairs. The same section directs the DNR to adopt rules governing dam safety. The specific rules governing Minnesota's Dam Safety Program are parts 6115.0300 through 6115.0520 defining which dams are subject to state jurisdiction and establishing three dam hazard classes.
State dam safety rules do not apply to dams that are so low (six feet high or less) or retain so little water (15 acre-feet or less) that they don't pose a threat to public safety or property (note that Public Water Rules may still apply). See figure above or enlarged version ). Some larger dams may also be exempt if there is no potential for loss of life due to failure or improper operation.
The DNR Division of Ecological and Water Resources maintains data on Minnesota dams that are included in the National Inventory of Dams (NID) database. This data includes the dam name, location, owner, purpose, hazard classification, structural condition, and about 50 other data elements. Over 1,250 Minnesota dams are currently listed in the inventory. Dam location and other information on dams statewide can be found on the interactive Dam Finder.
The Dam Safety Program keeps a file on all dams that are subject to state dam safety regulations or have had information or reports generated on them for another purpose. A typical file contains construction plans, photos, inspection reports, and correspondence.
All state-regulated high hazard dams are inspected annually by DNR Dam Safety engineers while lower hazard dams are inspected less frequently. Some inspections are also performed by professional engineers working for the U.S. Army Corps of Engineers, the Natural Resources Conservation Service, the Federal Energy Regulatory Commission, local units of government, and private dam owners. Some dams have instrumentation to warn of internal changes that may indicate a deterioration of their structural integrity.
High hazard dams have emergency action plans which need to be reviewed and revised as necessary on a periodic basis.
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.
Minnesota Statutes, Section 103G.511, authorize a state dam safety grant program. Grants to local units of government may be made for dam repair, reconstruction, or removal. Funds used for these grants come from state bonding appropriations through legislative action. In each odd-numbered year, the DNR submits a priority list of dams in need of repair, reconstruction, or removal to the legislature.
Some older dams no longer provide sufficient benefits to compensate for their public safety hazards, environmental damages, or repair and maintenance costs. In these cases, the state may provide up to 100% grants for removal.
Among the initiatives of the Ecological and Water Resources Division is stream restoration. Removal or modification of dams and restoration of stream function and stability are designed to eliminate safety hazards and improve property values, fish and wildlife habitat, water quality, water availability and recreational value.
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:
If you have questions about a particular dam or want further information about the Minnesota Dam Safety Program or a print-ready version of this brochure, contact the Dam Safety Program staff in St. Paul.