Mosquito Flat

CHALLIS CREEK SALMON RIVER· Custer, Idaho· Built 1950· 58 ft tall
Significant Hazard Other Private

Key Takeaway

Mosquito Flat is classified as significant hazard in Idaho. It was completed in 1950 and is 76 years old. Its primary use is other. Significant hazard means failure could cause economic or environmental damage. Learn more.

Physical Details

Dam Height 58 ft (taller than 82.8% in ID)
Dam Length450 ft
Normal Storage793 acre-ft
Surface Area46 acres
Drainage Area16 sq mi
Max Discharge4,360 cfs
Year Completed1950 (76 years old)
Year Modified2009
NID IDID00139

Safety Information

Significant Hazard

No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities.

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

Emergency Action Plan: Yes
Last Inspection: August 31, 2017
State Regulated: Yes
Regulatory Agency: IDWR

Ownership

Private

Nearby Dams

Frequently Asked Questions

What is the hazard classification of Mosquito Flat?

Mosquito Flat is classified as Significant Hazard. No probable loss of human life, but can cause economic loss, environmental damage, or disruption of lifeline facilities. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Mosquito Flat?

Mosquito Flat is owned by information not available (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Mosquito Flat built?

Mosquito Flat was completed in 1950, making it 76 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 Mosquito Flat?

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

How tall is Mosquito Flat?

Mosquito Flat has a dam height of 58 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.

When was Mosquito Flat last inspected?

Mosquito Flat was last inspected on August 31, 2017. Inspection dates indicate when a formal review occurred, not the results of that inspection.

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.