Oligarchy #1

Oligarchy #1 is an earth dam located in Boulder County, Colorado, built in 1889. It carries a Significant hazard potential classification and has a satisfactory condition assessment.

About Oligarchy #1

The primary purpose of Oligarchy #1 is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Oligarchy Reservoir Company (tipton, President, Ne (private). It impounds the St. Vrain Creek-os near Longmont.

The dam stands 33 feet tall and stretches 1,040 feet across, creates a reservoir covering 97 acres, and has a maximum storage capacity of 2,161 acre-feet. Completed in 1889, the structure is over a century old.

This dam has a significant hazard potential classification, meaning that a failure could cause significant economic damage — flooding roads, bridges, or property downstream — but is not expected to result in loss of life. Its condition is rated satisfactory, indicating no existing or potential dam safety deficiencies are recognized. An emergency action plan is in place for this dam. The most recent inspection on record was 06/10/2022.

At 33 feet, this dam is taller than 78% of dams nationwide.

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Significant HazardSatisfactory ConditionEmergency Action Plan: Yes

Location

StateColorado
CountyBoulder
Nearest CityLongmont
River/StreamSt. Vrain Creek-os
Coordinates40.19836, -105.19178

Physical Characteristics

Dam TypeEarth
NID Height33 ft
Dam Height29 ft
Dam Length1,040 ft
Year Completed1889 (137 years old)

Storage & Hydraulics

NID Storage2,161 acre-ft
Max Storage2,161 acre-ft
Normal Storage1,737 acre-ft
Surface Area97 acres
Max Discharge1,580 cfs
Spillway TypeUncontrolled

Ownership & Safety

PurposeIrrigation
OwnerOLIGARCHY RESERVOIR COMPANY (TIPTON, PRESIDENT, NE
Owner TypePrivate
Hazard ClassificationSignificant
Condition AssessmentSatisfactory
Last Inspection06/10/2022
Emergency Action PlanYes

Identifiers

NID IDCO01236
Federal IDCO01236
More InfoState Dam Safety Program

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