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Painted Rocks Dam. We need to act now.

by Dallas Erickson

To whom it may concern:

I am not writing this as a representative of the Red Cross but as the Disaster Chair for Ravalli County I have some concerns about the county’s readiness for disasters here in the valley in several respects.  To mitigate of the seriousness of potential disasters it will take the cooperation of the community as a whole.

One of my major concerns is that this county has more “high hazard” dams than any other county in the state.  High hazard does not speak to the condition of the dams but refers to property damage and lives that could be lost in case of a failure.

Two dams that would likely have significant property damage and loss of life would be Como Dam and Painted Rocks Dam.  It is our hope that the powers that control these dams conduct due diligence to do everything possible to reduce the risk of dam failure and install warning devices to save lives.  There has been public discussion and discourse about Como dam which is regulated by the Bureau of Reclamation. Such a discourse occurred last year which was fruitful and a good beginning. However, there are several things that can be done to mitigate the number of lives lost if there was a failure of that dam.  The Painted Rocks dam is of greater concern for several reasons including the design of the dam and the lack of public discussion on the Emergency Action Plan (EAP) and lack of a plan that would save lives in a dam failure.

To effectively prepare for any dam failure one has to plan for a total inundation of the dam.  From that standpoint, in the present EAP, multiple lives, possibly thousands, would be lost in any event that happened when no one was standing at the dam as an “observer” as the Emergency Action Plan (EAP) states. Even a serious leak in the dam could cause total failure in minutes.

Here are my major concerns about Painted Rocks Dam (Some apply to Como):

  • The EAP only works if someone is physically at the Dam when an “event” happens such as a breach of the dam, compromise of the dam because of seepage, or any disaster such as an earthquake or extreme weather such as occurred in Colorado recently.  The EAP starts with an “observer”.
  • If the dam was inundated it would within minutes take out the people in the campgrounds below the dam and destroy any possible communications systems and the residents and agencies in the West Fork Valley that are anywhere near the West Fork.
  • According to the EAP it would arrive in Darby with in the worst case scenario in 2.3 hours at a height of over 25 feet (as measured in the center of the river).  In clear dry weather it would arrive in 4.7 hours with a height of over 21 feet.

(PMFB stands for Probable Maximum Flood Breach and CWB stands for Clear Weather Breach)

  • According to the EAP it would arrive in Hamilton, worst case, in 5 hours at a height of over 25 feet and would rise to 43 feet.  In clear dry weather a breach would arrive at the North end of Hamilton in 8 hours at a height of 20 feet.
  • According to the calculations an inundation would cover all of Hamilton to the East of the Fair Grounds.
  • Remember this would not just be water but debris from houses, trees, cars, rocks and other materials that would add to the destructive power of the wave of water.
  • Further down it would even hit Corvallis.
  • It would skirt Stevensville wiping out the sewer system.  It would not touch the town of Florence or Lolo but would do major damage to housing developments in those areas on the East side and near the river on both sides.  Best estimate is that it would wipe out all the bridges on the river isolating the East and West side and leaving the East side without direct access to Missoula.
  • Remember that the Hamilton Hospital and medical facilities would be underwater as would the 911 center and the Sheriff’s Office.  The Rocky Mountain lab would be directly in the path of the flood as well.
  • If Painted Rocks became compromised at midnight (when there likely would be no “observers” and if there was what is the likelihood that they would have communications) the resulting flood could wipe out Darby and Hamilton before there was any warning at all.

Taking into account the potential for horrendous loss of life and destruction of property in the valley in the case of an inundation of the Painted Rocks Reservoir what can be done to mitigate these damages?

In the opinion of many, the Painted Rocks dam (and the Como Lake Dam) should have several redundant systems that notify a live person (such as at the 911 Center) if the earth at the dam moves or if the water in the West Fork raises a certain amount in a limited time frame.  This should be the minimum protection of our valley.  These redundant systems could contact several departments and people.  A plan then needs to be put together on how to notify the residents which would overwhelm the existing first responders.  Remember this resulting flood would cover the heaviest populated areas of the valley.

When I hike I carry a SPOT.  If I need help I push a button and a satellite is signaled and 911 is called.  The SPOT costs me $100 for the unit and about $100 per year for access to the satellite.  I know the systems would have to be much more complicated and expensive than a SPOT but their signal would be isolated from any outside power requirements and would be self-contained and would communicate through satellites.

What price can we put on lives that would be lost if action isn’t taken now?  Sure the dams haven’t failed yet but the Painted Rocks Dam is getting old and just last year we saw in the news where 7 inches of 12 inches of concrete had been eaten away by the force of the water.  Were the remaining 5 inches keeping the dam intact?

There is no need to panic, of course, but it is time to act.  The powers that be need to protect the citizens of our valley from these potential disasters.  Those who own the dam and those who regulate it need to do something now.  Let us start the discussion so we can all be assured that everything necessary will be done to warn us of impending disaster.

The County Commission Contact numbers are found at: and the main number listed here:

215 S 4th Street
Suite A
Hamilton, MT 59840

Phone: 406-375-6500

You can email all the commissioners at:

You can contact the Department of Natural Resources and Conservation at:

DNRC Water Resources Division
1424 Ninth Avenue
PO Box 201601
Helena Montana 59620-1601

(406) 444-6601

Their website is:

The link below has more information on the dams in Montana which are regulated by the agency.

One of my favorite sayings is: Remember the formula: A + P = R (Apathy + Procrastination = Regret).  If the worst was to happen I pray that we are prepared and that will only happen if the people speak out.

Thank you.
Dallas D. Erickson