Rattlesnake Reservoir

TWELVEMILE CREEK-OFFSTREAM· Yellowstone, Montana· Built 1909· Earth· 14 ft tall
Low Hazard Irrigation Private

Key Takeaway

Rattlesnake Reservoir is classified as low hazard in Montana. It was completed in 1909 and is 117 years old. Its primary use is irrigation.

Physical Details

Dam Height 14 ft (taller than 15.6% in MT)
Dam Length4,752 ft
Dam TypeEarth
Max Storage715 acre-ft
Normal Storage715 acre-ft
Surface Area179 acres
Year Completed1909 (117 years old)
NID IDMT02427

Safety Information

Low Hazard

No probable loss of human life and low economic/environmental losses expected.

Hazard potential describes downstream consequences of failure, not the dam's current condition. What does this mean?

Emergency Action Plan: No
State Regulated: Yes
Regulatory Agency: DNRC

Ownership

BILLINGS BENCH WATER ASS'N

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Rattlesnake Reservoir?

Rattlesnake Reservoir is classified as Low Hazard. No probable loss of human life and low economic/environmental losses expected. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Rattlesnake Reservoir?

Rattlesnake Reservoir is owned by BILLINGS BENCH WATER ASS'N (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Rattlesnake Reservoir built?

Rattlesnake Reservoir was completed in 1909, making it 117 years old. Many U.S. dams were built between the 1930s and 1970s during a period of major infrastructure investment.

What is the primary purpose of Rattlesnake Reservoir?

Rattlesnake Reservoir serves the following purposes: Irrigation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Rattlesnake Reservoir?

Rattlesnake Reservoir has a dam height of 14 ft. Dam height is measured from the natural streambed at the downstream toe to the top of the dam, and may differ from the visible height.

Data from the National Inventory of Dams (NID) maintained by the US Army Corps of Engineers. Dam conditions may have changed since the last update. This site is not affiliated with USACE. Do not use for emergency planning — contact your local dam safety program.