Johnston
Johnston is an earth dam located in Jefferson County, Colorado, built in 1974. It carries a Significant hazard potential classification and has a satisfactory condition assessment.
About Johnston
The primary purpose of Johnston is irrigation. The dam stores and diverts water for agricultural irrigation, supporting farming operations in the surrounding area. The dam is owned by Foothills Park & Recreation District (insley, Coli (private). It impounds the Lilley Gulch near Littleton.
The dam stands 17 feet tall and stretches 1,530 feet across, creates a reservoir covering 82 acres, and has a maximum storage capacity of 1,134 acre-feet. Completed in 1974, the structure is well into its service life at over 50 years 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 03/23/2022.
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Location
| State | Colorado |
| County | Jefferson |
| Nearest City | Littleton |
| River/Stream | Lilley Gulch |
| Coordinates | 39.60307, -105.08411 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 17 ft |
| Dam Height | 11 ft |
| Dam Length | 1,530 ft |
| Year Completed | 1974 (52 years old) |
Storage & Hydraulics
| NID Storage | 1,134 acre-ft |
| Max Storage | 1,134 acre-ft |
| Normal Storage | 547 acre-ft |
| Surface Area | 82 acres |
| Max Discharge | 3,650 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Irrigation |
| Owner | FOOTHILLS PARK & RECREATION DISTRICT (INSLEY, COLI |
| Owner Type | Private |
| Hazard Classification | Significant |
| Condition Assessment | Satisfactory |
| Last Inspection | 03/23/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | CO01827 |
| Federal ID | CO01827 |
| More Info | State Dam Safety Program |