Thayer No. 1

GREYBULL RIVER, OFF CARTER MTN· Park, Wyoming· Built 1935· Earth· 13 ft tall

Low Hazard Irrigation Private

Key Takeaway

Thayer No. 1 is classified as low hazard in Wyoming. It was completed in 1935 and is 91 years old. Its primary use is irrigation.

Physical Details

Dam Height	13 ft (taller than 7.6% in WY)
Dam Length	120 ft
Dam Type	Earth
Max Storage	69 acre-ft
Normal Storage	69 acre-ft

Surface Area	17 acres
Drainage Area	0 sq mi
Max Discharge	0 cfs
Year Completed	1935 (91 years old)
NID ID	WY01909

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

Last Inspection: September 19, 2019

State Regulated: Yes

Regulatory Agency: SEO

Ownership

HOODOO LAND HOLDINGS, LLC

Private

Nearby Dams

Thomas

Park, WY

Low Hazard 56 ft

Frequently Asked Questions

What is the hazard classification of Thayer No. 1?

Thayer No. 1 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 Thayer No. 1?

Thayer No. 1 is owned by HOODOO LAND HOLDINGS, LLC (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Thayer No. 1 built?

Thayer No. 1 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 Thayer No. 1?

Thayer No. 1 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 Thayer No. 1?

Thayer No. 1 has a dam height of 13 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 Thayer No. 1 last inspected?

Thayer No. 1 was last inspected on September 19, 2019. 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.