High Hazard Dams in Montana – Know the Rules

High Hazard Dams in Montana - Know the Rules

Do kids still venture out like they used to?  Do they explore the outdoors with a passion, waiting for the first signs of spring to head out and discover what the Big Sky of Montana can offer?  If so, are the warnings that I received as a youngster still echoed by parents of today?

via GIPHY

Growing up ranching, we were told some very specific things when we were turned loose to fend for ourselves during the days.  One of those dealt with stock dams dotted across properties.  Instructed to never play around them, the lesson continued as I moved into town and the larger concrete dams came into play.  Never play around them.  And there was a good reason that parents or teachers or elders told us this.

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How Many Real Dams Are in the State of Montana

While Montana is home to over 64,000 reservoirs, 3,259 are actual dams by definition from the National Dam Inventory Criteria.  Of those, there are 3 different definitions and classifications of them.

Hazard classification for dams in Montana are as follows:

1. High Hazard Dams - those that have a chance of loss of life should they fail
2. Significant Hazard Dams - those that have a chance of loss of property damage
3. Low Hazard Dams - those that have low damage potential in failure

For our state, 197 of those dams are listed as high hazard, 201 as significant and nearly 2,900 are considered low hazard.

The Number One Problem Facing Dams in Montana

With so many dams around the state, there has to be some failures eventually.  Those failures are related to one thing in those dams.  The pipes.  Many dams were built during the period between 1940 and 1960.  During that time, many pipes were of corrugated metal.

Corrugated metal pipes will slowly corrode over time. In recent years, many dam failures have been caused by failure of CMP outlets. Failure usually occurs catastrophically and with little warning.

Most of the high hazard dams in Montana have rehabilitated their aging outlets, but owners of many small low hazard dams are not aware of the need to inspect and if necessary, repair or replace their outlets, as inspections are not required.