Lower Chinns dam
Lower Chinns
Lower Chinns is a private-owned earth dam located in Idaho Springs, Colorado, along the Fall River. Built in 1934, this dam serves primarily for irrigation purposes, but also supports recreation and water supply activities. Standing at a height of 18 feet with a hydraulic height of 13 feet, Lower Chinns has a storage capacity of 170 acre-feet and covers a surface area of 12 acres.
Despite its age, Lower Chinns is in satisfactory condition according to a recent assessment in July 2020, with a high hazard potential due to its location and design. The dam has a spillway width of 37 feet and a maximum discharge capacity of 560 cubic feet per second. While the risk assessment deems it moderate, appropriate risk management measures are in place to ensure the safety of the surrounding areas in case of emergencies. Managed by the Colorado Department of Water Resources, Lower Chinns plays a crucial role in the water resource management of Clear Creek County, demonstrating the intersection of infrastructure, climate resilience, and environmental stewardship.
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 Lower Chinns -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Fraser River At Upper Sta | 22 cfs | → |
| West Fork Clear Creek Abv Mouth Nr Empire | 49 cfs | → |
| Berthoud Pass Ditch At Berthoud Pass | -999 cfs | → |
| Clear Creek Abv West Fork Clear Creek Nr Empire Co | 66 cfs | → |
| Clear Creek Near Lawson | 111 cfs | → |
| Moffat Water Tunnel At East Portal | 204 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lower Chinns.
Boat launches
- Miramonte Road Boulder County
- Fairway Drive Evergreen
- Cr 6 Grand County
- Ralston Creek Trail Arvada
- Willow Creek Boating Site
- Us 34 Grand County
Campgrounds
- Robbers Roost
- Robbers Roost Campground
- Empire City Rv Parking
- Midland Group Campground
- Jim Creek Campground
- Georgetown Lake
Fishing spots
Paddle runs
- Upper South Boulder Creek
- Upper Clear Creek
- Lower Snake
- Tunnel 1 To Golden Whitewater Park
- Silverthorne Town Run
More reservoirs
Track Lower Chinns 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 Lower Chinns
Where does the data for Lower Chinns 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 Lower Chinns.