Johnston dam
Johnston
Johnston is a privately-owned dam located in Littleton, Colorado, along the Lilley Gulch river. Completed in 1974, this earth dam stands at a height of 11 feet with a hydraulic height of 17 feet, serving primarily for irrigation purposes. With a storage capacity of 1134 acre-feet and a surface area of 82 acres, Johnston plays a crucial role in water resource management in the region.
Maintained by the Colorado Department of Water Resources, Johnston has a significant hazard potential but is currently assessed to be in satisfactory condition as of February 2020. The dam has a moderate risk level, with regular inspections conducted every two years to ensure its safety and functionality. Despite its age, Johnston continues to provide vital water resources for irrigation and recreational activities in the area.
With its uncontrolled spillway and a maximum discharge of 3650 cubic feet per second, Johnston remains an important infrastructure for water management in Jefferson County, Colorado. As climate change continues to impact water resources, the maintenance and regulation of dams like Johnston are essential to ensure the sustainable use of water for agricultural and recreational purposes in the region.
Dam data reference
Condition Assessment
- Satisfactory
- No existing or potential dam safety deficiencies are recognized. Acceptable performance is expected under all loading conditions (static, hydrologic, seismic) in accordance with the minimum applicable state or federal regulatory criteria or tolerable risk guidelines.
- Fair
- No existing dam safety deficiencies are recognized for normal operating conditions. Rare or extreme hydrologic and/or seismic events may result in a dam safety deficiency. Risk may be in the range to take further action.
- Poor
- A dam safety deficiency is recognized for normal operating conditions which may realistically occur. Remedial action is necessary. POOR may also be used when uncertainties exist as to critical analysis parameters which identify a potential dam safety deficiency.
- Unsatisfactory
- A dam safety deficiency is recognized that requires immediate or emergency remedial action for problem resolution.
- Not Rated
- The dam has not been inspected, is not under state or federal jurisdiction, or has been inspected but, for whatever reason, has not been rated.
Hazard Potential Classification
- High
- Dams assigned the high hazard potential classification are those where failure or mis-operation will probably cause loss of human life.
- Significant
- Dams assigned the significant hazard potential classification are those dams where failure or mis-operation results in no probable loss of human life but can cause economic loss, environmental damage, disruption of lifeline facilities, or impact other concerns. Significant hazard potential classification dams are often located in predominantly rural or agricultural areas but could be in areas with population and significant infrastructure.
- Low
- Dams assigned the low hazard potential classification are those where failure or mis-operation results in no probable loss of human life and low economic and/or environmental losses. Losses are principally limited to the owner's property.
- Undetermined
- Dams for which a downstream hazard potential has not been designated or is not provided.
Plan around the weather
Same NOAA / yr.no feed Snoflo's iOS app uses. Watch the precipitation column on the meteogram -- rain on the basin upstream typically lifts inflow 24-72 hours later.
Next 5 days, hour by hour
Temperature line with weather symbols on top, snow + rain accumulation as columns, humidity as a dotted line.
5-day forecast table
Every 3 hours, broken out across temperature, snow, rain, humidity, and wind. Each cell is colour-coded relative to the column min/max.
| Time | Condition | Temp (°F) | Snow (in) | Rain (in) | Humidity (%) | Wind (mps) | Wind dir |
|---|---|---|---|---|---|---|---|
| Loading detailed forecast… | |||||||
15-day temperature & precipitation
Daily temperatures, snow, and rain projected over the next two weeks.
Nearby streamflow gauges
USGS streamgauges around Johnston -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| South Platte River Below Union Ave | 24 cfs | → |
| Bear Creek At Mouth | 8 cfs | → |
| Bear Creek Above Bear Creek Lake Near Morrison | 5 cfs | → |
| South Platte River At Englewood | 32 cfs | → |
| Bear Creek At Morrison | 18 cfs | → |
| Plum Creek At Titan Rd Nr Louviers | 18 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Johnston.
⚓ Boat launches
- West Quincy Avenue Denver
- Chatfield Lake North Boat Ramp
- Fisherman's Trail Lakewood
- C-470 Trail Lakewood
- Cherry Creek Park Road Centennial
- Fairway Drive Evergreen
⛺ Campgrounds
- Chatfield State Park
- Bear Creek Lake Park
- Idylease Campground
- Clear Creek Rv Park
- Chief Ouray Group Site
- Cherokee Group Site
🎣 Fishing spots
More fishing →Track Johnston in the Snoflo app
Save this dam as a favorite and get the local NOAA / yr.no forecast plus regional flow context wherever you are.
About Johnston
Where does the data for Johnston come from?
Structural and regulatory data come from the U.S. Army Corps of Engineers' National Inventory of Dams (NID). Weather forecast comes from NOAA / yr.no -- the same feed Snoflo's iOS app uses.
How often is the report updated?
NID structural data refreshes annually as the Corps publishes updated assessments. The weather forecast refreshes throughout the day.
What does the Significant hazard rating mean?
The Corps of Engineers' hazard potential classification grades probable consequences if the dam fails: High = probable loss of human life; Significant = no probable loss of human life but possible economic loss / environmental damage; Low = no probable loss of human life, only minor economic / environmental losses. See the Dam Data Reference card above for the full definitions.
What's "% of normal"?
The current storage value compared to the historical average storage on this calendar day. 100% = right on average; values above 100% mean above-normal storage (wet year); values below mean below-normal (dry year or drought).
Can I get alerts when storage crosses a threshold?
Yes -- alerts are managed in the Snoflo iOS app. Favorite this dam, set a threshold, and you'll get a push the moment conditions cross.
Other water bodies near here
Snoflo-tracked reservoirs and dams within driving distance of Johnston.