Dam safety

Dam Safety in Minnesota, an on-line brochure

State Dam Safety Program Overview | Program Components | Responsibility and Liability of Dam Owners

Importance of dam safety

Dams provide many benefits and are an important part of our civil works infrastructure. They are built for a variety of reasons, including maintenance of lake levels, flood control, power production, and water supply. Dams fail due to inadequate design, improper operation, inadequate maintenance, or unusually large floods. Dam failure can result in the quick release of all the water in the reservoir; the rapid and unexpected flooding downstream can cause loss of life and significant property damages.

State Dam Safety Program Overview

Minnesota's Dam Safety Program was created in 1978 in response to the federal Dam Safety Act. A series of major dam failures killed scores of people in the 1970's and prompted Congress to pass the act to improve dam safety nationally.

Minnesota's program includes enabling legislation, agency rules for construction and operation, creation of a dam database, permitting requirements, regular inspections, repair of state-owned dams, and cost-share grants for dam repairs by local units of government.

The Dam Safety Program regulates the repair, operation, design, construction, and removal of dams. Both privately and publicly owned dams are regulated. The program sets minimum standards for dams regarding safety, design, construction, and operation. These standards are implemented through inspections, permitting, and correcting deficiencies.

Program Components

Enabling Legislation. Minnesota Statutes, Section 103G.515 authorizes the DNR commissioner to inspect dams and issue orders directing dam owners to make necessary repairs. The same section directs the commissioner to adopt rules governing dam safety.

Agency Rules. Minnesota Rules, parts 6115.0300 through 6115.0520 govern the state Dam Safety Program. The rules define which dams are subject to state jurisdiction, and establishes three dam hazard classes.

State dam safety regulations apply only to structures that pose a potential threat to public safety or property. The potential for damage downstream if a dam fails increases as the height of the dam and the volume of impounded water increases. State dam safety rules do not apply to dams that are so low or retain so little water as to not pose a threat to public safety or property.

Dams 6 feet high or less, regardless of the quantity of water they impound, and dams that impound 15 acre-feet of water or less, regardless of their height, are exempt from state dam safety rules. Dams that are less than 25 feet high and impound less than 50 acre-feet are also exempt from state dam safety rules unless there is a potential for loss of life due to failure or misoperation. Figure 1 shows these criteria in a graphical form.

Dam Database. In cooperation with the Federal Emergency Management Agency and the Association of State Dam Safety Officials, the DNR Division of Waters maintains Minnesota's component of the National Dam Inventory (NATDAM). NATDAM presently includes information only on those dams meeting the threshold of state dam safety rules. About 900 dams are currently listed in the system. NATDAM can store information on dam name, location, purpose, hazard classification, structural condition, and about 30 other data elements.

Permits. Permits are required to perform major maintenance, modify dam operation, reconstruct a dam, remove a dam, transfer dam ownership, or build a new dam. Plans for construction must be completed by a professional engineer experienced in dam engineering.

Permit Guidelines for Dams

Inspections. Dams designated as High Hazard are inspected annually and lower hazard dams are inspected less frequently by DNR dam safety engineers.

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, and private dam owners. Dams being built or having major repair also require state inspection. High hazard dams have emergency action plans, which need to be monitored and revised as necessary on a periodic basis. Some dams have instrumentation to warn of internal changes that may indicate a deterioration of their structural integrity, and these dams need to be checked on a regular basis.

Repairs and Removals. The DNR repairs and maintains state-owned dams. Minnesota Statutes, Section 103G.511 authorizes a state dam safety cost-share program. The DNR commissioner may make grants to local units of government for dam repair, reconstruction, or removal. Funding for repair or removal is provided by the legislature through state bonding appropriations.

Some older dams no longer provide sufficient benefits to compensate for their environmental damages, public safety hazards, and repair/maintenance costs. In these cases, the state provides grants only for their removal.

Responsibility and Liability of Dam Owners

Maintenance and Operation. Dam owners have a clear responsibility to properly maintain, repair, and operate their dams. Existing dams may also have to be improved to meet current dam safety criteria. If development downstream raises the hazard associated with a potential failure, the owner may be required to bring the dam into compliance with a higher standard commensurate with the new conditions.

Liability from Failure or Misoperation. The owner of a dam could be found liable for damages incurred from a failure or misoperation. Compliance with state standards may not protect the owner. Damages from failures can be very significant.

Environmental and Other Concerns. Construction and operation of dams can have varied impacts upstream, downstream, and to surrounding lands. Losses suffered by other parties can become liabilities to a dam owner. These impacts could include:

raising or lowering of ground water levels that affect wells or crops,
increased downstream flooding caused by improper operation,
drowning of anglers or swimmers because of improper operation,
damage to a fishery because of improper operation,
channel degradation because of interruption of sediment transport, and
water quality degradation because of reservoir siltation and stagnant water conditions.

Additional Information

For further information about the Minnesota Dam Safety Program or for a copy of the brochure with this information, you may contact the DNR Waters regional office staff in your area or contact the Dam Safety Program staff in St. Paul.