Ashton

Henrys Fork, Snake River· Fremont, Idaho· Built 1917· Earth· 65 ft tall

High Hazard Irrigation Recreation Hydroelectric Water Supply Private

Key Takeaway

Ashton is classified as high hazard in Idaho. It was completed in 1917 and is 109 years old. Its primary use is irrigation. High hazard means loss of life is likely if the dam fails — it does not indicate the dam's current condition. Learn more.

Physical Details

Dam Height	65 ft (taller than 85.9% in ID)
Dam Length	252 ft
Dam Type	Earth
Max Storage	9.9K acre-ft
Normal Storage	9.8K acre-ft

Surface Area	404 acres
Drainage Area	1,040 sq mi
Max Discharge	46,100 cfs
Year Completed	1917 (109 years old)
NID ID	ID00178

Safety Information

High Hazard

Loss of human life is likely if the dam fails.

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

Emergency Action Plan: Yes

Last Inspection: October 20, 2022

State Regulated: Yes

Regulatory Agency: IDWR

Ownership

PacifiCorp

Private

Nearby Dams

Egbert Dam

Fremont, ID

Low Hazard 15 ft

Seeley Lower

Fremont, ID

Low Hazard 14 ft

Henrys Fork Ranch

Fremont, ID

Low Hazard 23 ft

Mikesell Upper

Fremont, ID

Low Hazard 16 ft

Cross Cut Diversion

Fremont, ID

Low Hazard 18 ft

Arcadia Lower

Fremont, ID

Low Hazard 23 ft

Arcadia Upper

Fremont, ID

Low Hazard 21 ft

Egin Canal Diversion

Fremont, ID

Low Hazard 7 ft

Frequently Asked Questions

What is the hazard classification of Ashton?

Ashton is classified as High Hazard. Loss of human life is likely if the dam fails. This classification refers to the potential downstream consequences of a failure, not the dam's current structural condition.

Who owns and operates Ashton?

Ashton is owned by PacifiCorp (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Ashton built?

Ashton was completed in 1917, making it 109 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 Ashton?

Ashton serves the following purposes: Irrigation, Recreation, Hydroelectric, Water Supply. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Ashton?

Ashton has a dam height of 65 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 Ashton last inspected?

Ashton was last inspected on October 20, 2022. 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.