Isabel

TR. OF FIRESTEEL CREEK· Dewey, South Dakota· Built 1935· Earth· 30 ft tall

High Hazard Recreation State Government

Key Takeaway

Isabel is classified as high hazard in South Dakota. It was completed in 1935 and is 91 years old. Its primary use is recreation. 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	30 ft (taller than 85.2% in SD)
Dam Length	1,200 ft
Dam Type	Earth
Max Storage	2.4K acre-ft
Normal Storage	537 acre-ft

Surface Area	115 acres
Drainage Area	10 sq mi
Max Discharge	11,621 cfs
Year Completed	1935 (91 years old)
Year Modified	1997
NID ID	SD00014

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: November 10, 2021

State Regulated: Yes

Regulatory Agency: DANR

Ownership

GF&P

State Government

Nearby Dams

John Meginess

Dewey, SD

Low Hazard 25 ft

R. Clark No.3

Dewey, SD

Low Hazard 11 ft

R. Clark No.2

Dewey, SD

Low Hazard 12 ft

R. Clark No.1

Dewey, SD

Low Hazard 19 ft

Bill Lindskou

Corson, SD

Low Hazard 19 ft

G&J Heck No.2

Dewey, SD

Low Hazard 25 ft

G&J Heck No.1

Dewey, SD

Low Hazard 15 ft

D. Woddell

Dewey, SD

Low Hazard 24 ft

Frequently Asked Questions

What is the hazard classification of Isabel?

Isabel 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 Isabel?

Isabel is owned by GF&P (State Government). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Isabel built?

Isabel was completed in 1935, making it 91 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 Isabel?

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

How tall is Isabel?

Isabel has a dam height of 30 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 Isabel last inspected?

Isabel was last inspected on November 10, 2021. 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.