Mariano

BIG THOMPSON RIVER-TR· Larimer, Colorado· Built 1889· Earth· 30 ft tall

High Hazard Irrigation Fish And Wildlife Pond Recreation Private

Key Takeaway

Mariano is classified as high hazard in Colorado. It was completed in 1889 and is 137 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	30 ft (taller than 65.6% in CO)
Dam Length	1,420 ft
Dam Type	Earth
Max Storage	7.7K acre-ft
Normal Storage	5.6K acre-ft

Surface Area	374 acres
Drainage Area	2 sq mi
Max Discharge	1,640 cfs
Year Completed	1889 (137 years old)
NID ID	CO00166

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: July 11, 2022

State Regulated: Yes

Regulatory Agency: DWR

Ownership

CONSOLIDATED HOME SUPPLY DITCH & RES. CO (DAVE SCH

Private

Nearby Dams

Cattail #1

Larimer, CO

Low Hazard 10 ft

George Rist

Larimer, CO

Significant Hazard 17 ft

Cattail Pond

Larimer, CO

Low Hazard 7 ft

Lon Hagler

Larimer, CO

High Hazard 60 ft

South Side

Larimer, CO

Significant Hazard 31 ft

Rist - Benson

Larimer, CO

High Hazard 15 ft

Ryan Gulch

Larimer, CO

Significant Hazard 36 ft

Lone Tree

Larimer, CO

Significant Hazard 29 ft

Frequently Asked Questions

What is the hazard classification of Mariano?

Mariano 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 Mariano?

Mariano is owned by CONSOLIDATED HOME SUPPLY DITCH & RES. CO (DAVE SCH (Private). The owner is responsible for maintenance, inspections, and compliance with dam safety regulations.

When was Mariano built?

Mariano was completed in 1889, making it 137 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 Mariano?

Mariano serves the following purposes: Irrigation, Fish And Wildlife Pond, Recreation. Many dams in the U.S. are multi-purpose, supporting flood control, water supply, recreation, and other uses.

How tall is Mariano?

Mariano 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 Mariano last inspected?

Mariano was last inspected on July 11, 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.