Costich Dam
Costich Dam is an earth dam located in Lincoln County, Montana, built in 1956. It carries a High hazard potential classification and has a satisfactory condition assessment.
About Costich Dam
The primary purpose of Costich Dam is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Glen Lake Irrigation District (local government). It impounds the Tr-tobacco River Offstream near Eureka.
The dam stands 29 feet tall and stretches 215 feet across, creates a reservoir covering 44 acres, has a maximum storage capacity of 570 acre-feet, and collects water from a drainage area of 0 square miles. Completed in 1956, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 06/22/2020.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Montana dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Montana |
| County | Lincoln |
| Nearest City | Eureka |
| River/Stream | Tr-tobacco River Offstream |
| Coordinates | 48.89136, -115.02316 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 29 ft |
| Dam Height | 29 ft |
| Dam Length | 215 ft |
| Year Completed | 1956 (70 years old) |
Storage & Hydraulics
| NID Storage | 570 acre-ft |
| Max Storage | 570 acre-ft |
| Normal Storage | 470 acre-ft |
| Surface Area | 44 acres |
| Drainage Area | 0 sq mi |
| Max Discharge | 82 cfs |
| Spillway Type | None |
Ownership & Safety
| Purpose | Irrigation |
| Owner | GLEN LAKE IRRIGATION DISTRICT |
| Owner Type | Local Government |
| Hazard Classification | High |
| Condition Assessment | Satisfactory |
| Last Inspection | 06/22/2020 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | MT01025 |
| Federal ID | MT01025 |
| More Info | State Dam Safety Program |