Island Lake is a concrete dam located in Boulder County, Colorado, built in 1890. It carries a Low hazard potential classification and has a fair condition assessment.
Dam profile
NID height · 23 ft23 ft tall and 600 ft long. Height is drawn to scale against a two-story house, about 25 ft; the profile is a generic concrete gravity section and the water level is illustrative.
About Island Lake
The primary purpose of Island Lake is water supply. The dam stores water for municipal, industrial, or agricultural use, helping ensure a reliable supply for the surrounding area. The dam is owned by City of Boulder (clark, Kevin) (local government). It impounds the North Boulder Creek-tr near Boulder.
The dam stands 23 feet tall and stretches 600 feet across, creates a reservoir covering 35 acres, has a maximum storage capacity of 386 acre-feet, and collects water from a drainage area of 5 square miles. Completed in 1890, the structure is over a century old.
This dam has a low hazard potential classification, meaning that failure would cause minimal damage, limited primarily to the dam owner's property, with no expected loss of life. Its condition is rated fair — the dam has minor deficiencies that are being addressed or do not pose an immediate safety threat. The most recent inspection on record was 09/06/2017.
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Location
| State | Colorado |
| County | Boulder |
| Nearest City | Boulder |
| River/Stream | North Boulder Creek-tr |
| Coordinates | 40.02948, -105.59130 |
Physical Characteristics
| Dam Type | Concrete |
| NID Height | 23 ft |
| Dam Height | 18 ft |
| Dam Length | 600 ft |
| Year Completed | 1890 (136 years old) |
Storage & Hydraulics
| NID Storage | 386 acre-ft |
| Max Storage | 386 acre-ft |
| Normal Storage | 334 acre-ft |
| Surface Area | 35 acres |
| Drainage Area | 5 sq mi |
| Max Discharge | 400 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Water Supply |
| Owner | City of Boulder (clark, Kevin) |
| Owner Type | Local Government |
| Hazard Classification | Low |
| Condition Assessment | Fair |
| Last Inspection | 09/06/2017 |
| Emergency Action Plan | Not Required |
Identifiers
| NID ID | CO00228 |
| Federal ID | CO00228 |
| More Info | State Dam Safety Program |