Left Hand Valley dam
Left Hand Valley
Located in Boulder, Colorado, the Left Hand Valley dam, designed by Damon Runyan, stands as a critical infrastructure for irrigation purposes along Dry Creek. Completed in 1952, this private-owned Earth type dam boasts a height of 54 feet and a hydraulic height of 45 feet, with a storage capacity of 2814 acre-feet. Its spillway, with a width of 192 feet, serves as an uncontrolled outlet for excess water to prevent overflow.
With a high hazard potential and a satisfactory condition assessment, the Left Hand Valley dam is under state regulation and inspection by the Colorado Division of Water Resources. Despite its age, the dam continues to meet safety guidelines and poses a moderate risk (3) according to the latest risk assessment. The dam's emergency action plan was last revised in 2003, and it remains a crucial structure for water resource management and climate resilience in the region, serving as a lifeline for agricultural irrigation in the area.
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 Left Hand Valley -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Left Hand Creek Near Boulder | 36 cfs | → |
| Boulder Cr At North 75th St Nr Boulder | 37 cfs | → |
| Fourmile Creek At Orodell | 2 cfs | → |
| Left Hand Creek At Hover Road Near Longmont | 1 cfs | → |
| Boulder Creek Near Orodell | 63 cfs | → |
| St. Vrain Creek At Lyons | 89 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Left Hand Valley.
Boat launches
- Lagerman Trail Boulder County
- Miramonte Road Boulder County
- Standley Lake Trail Westminster
- Ralston Creek Trail Arvada
- West 69th Avenue 4700, Westminster
- Brighton
Campgrounds
Fishing spots
- Boulder Reservoir
- Coot Lake
- Wonderland Lake
- Maxwell Lake
- Lagerman Reservoir
- Walden Ponds - Ricky Weiser Wetland
Track Left Hand Valley 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 Left Hand Valley
Where does the data for Left Hand Valley 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 High 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 Left Hand Valley.