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DNRC Headquarters
1539 Eleventh Ave. Helena, MT 59601
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Hazard Classifications


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To build a new dam or alter an existing dam with an impoundment capacity of 50 acre feet or more, you must apply to the DNRC Dam Safety Program for a hazard classification.

So What is a Hazard Classification?

The determination of hazard involves an evaluation of the area downstream from the dam that would be flooded if the dam fails. If the flood would be likely to cause a loss of life, the dam or reservoir is classified as a high-hazard structure. The hazard classification is based on the potential loss of life downstream and is not an assessment of the safety of the structure.

What is Needed to Apply for A Hazard Classification?

The owner of a dam first needs to make an estimate of the impoundment capacity at the maximum normal operating pool, which is usually to the crest of the principal or emergency spillway. If the impoundment capacity is 50 acre-feet or more, a hazard classification is needed.

Application for Determination of Hazard Classification of Dams and Reservoirs - $125 Fee

Send this application to your Regional Engineer

What if My Dam Stores Under 50 Acre Feet?