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High Risk Dams in Montana

Montana has 38 high hazard dams with a condition assessment of poor or unsatisfactory. These are dams where failure would probably cause loss of human life and where recognized safety deficiencies have been identified.

Of the 190 high hazard dams in Montana, 38 (20%) have concerning condition ratings — 30 rated poor and 8 rated unsatisfactory.

Condition scale, best to worst
  1. Satisfactory No existing or potential safety deficiencies recognized; acceptable performance expected under all loading conditions.
  2. Fair No deficiencies under normal operating conditions; a rare flood or earthquake could create one.
  3. Poor A safety deficiency is recognized under normal operating conditions; remedial action is necessary.
  4. Unsatisfactory Worst rating. The dam is considered unsafe; a deficiency requires immediate or emergency remedial action.

"Not rated" means no assessment is on file in the National Inventory of Dams.

DamCountyHeight (ft)ConditionLast inspectedPurposeYear
Kootenai Dvlpmnt Impoundment DamLincoln151Poor10/25/20241 yr agoOther1980
West Fork Bitterroot (painted Rocks)Ravalli143Poor06/18/20242 yrs agoIrrigation1940
Newlan Creek DamMeagher131Poor06/17/20215 yrs agoIrrigation1977
HubbartFlathead130Poor08/17/20215 yrs agoIrrigation1923
Willow Creek DamMadison105Poor07/02/20242 yrs agoIrrigation1938
CooneyCarbon102Poor11/20/20241 yr agoIrrigation1937
CrowLake99Poor09/01/20224 yrs agoIrrigation1933
Lower Willow Creek DamGranite96Poor09/09/20215 yrs agoIrrigation1962
Cataract Creek DamMadison80Unsatisfactory10/13/20232 yrs agoIrrigation1959
PetroliaPetroleum76Poor04/26/20233 yrs agoIrrigation1951
Black LakeMissoula75Unsatisfactory10/05/20206 yrs agoRecreation1967
Three Mile Reservoir (l.&c.)Lewis and Clark70Poor10/20/20214 yrs agoIrrigation1926
Delmoe Lake DamJefferson60Poor10/16/20232 yrs agoIrrigation1914
Tabor SouthLake60Poor10/06/20206 yrs agoRecreation1930
PowellPowell52Poor06/13/20242 yrs agoIrrigation1981
JockoMissoula51Poor10/05/20206 yrs agoIrrigation1937
Martinsdale, East DamWheatland49Poor10/10/20241 yr agoIrrigation1939
Depression Detention DamCarbon42Poor07/09/20206 yrs agoFlood Risk Reduction1968
Black EagleCascade41Poor07/19/20224 yrs agoHydroelectric1891
Upper Dry ForkSanders40Unsatisfactory10/28/20205 yrs agoIrrigation1940
Cottonwood Dam (park)Park39Poor05/01/20242 yrs agoIrrigation1953
Jordan DamPark38PoorNot reportedIrrigation1961
Jackson (madison)Madison34Poor08/03/201511 yrs agoIrrigation1959
Jackson LakeMeagher32Unsatisfactory04/08/20206 yrs agoIrrigation1936
Eureka Reservoir DamTeton32Poor10/04/20233 yrs agoIrrigation1936
High LakeRavalli30PoorNot reportedIrrigation1938
Lower Glasston DamSweet Grass30Poor07/10/20215 yrs agoIrrigation1912
Kicking HorseLake30Unsatisfactory09/26/20224 yrs agoIrrigation1930
Hell RoaringLake30Unsatisfactory10/23/200718 yrs agoHydroelectric1916
Storm Lake DamDeer Lodge29Poor09/16/20242 yrs agoIrrigation1898
Boot Lake DamBeaverhead27Poor09/18/20242 yrs agoIrrigation1912
Upper Glasston West DamSweet Grass22Poor07/10/20215 yrs agoIrrigation1912
Bigfork Diversion DamFlathead22Poor06/04/20251 yr agoHydroelectric1910
Upper Glasston North DamSweet Grass20Poor07/10/20215 yrs agoIrrigation1912
Melstone Detention DamMusselshell19Unsatisfactory07/20/20206 yrs agoFire Protection, Stock, Or Small Fish Pond2003
Pear Lake DamBeaverhead19Poor09/18/20242 yrs agoIrrigation1904
Glen LakeLincoln14Poor06/22/20206 yrs agoIrrigation1950
Pablo North DikeLake5Unsatisfactory10/02/20206 yrs agoIrrigation1912

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