Duncan dam
Duncan
Duncan, also known as Twilight Lake, is a local government-owned water resource in Durango, Colorado. Managed by DAVIS ENGINEERING SERVICE, INC., this dam was completed in 1978 and serves multiple purposes including fish and wildlife pond, recreation, and other uses. With a height of 31 feet and a length of 180 feet, Duncan has a storage capacity of 78 acre-feet and covers a surface area of 7 acres, drawing water from Purgatory Creek-OS.
This earth dam, with an uncontrolled spillway and a slide gate outlet, poses a significant hazard potential but has been assessed to be in satisfactory condition as of July 2019. The dam is inspected every two years, with the last inspection conducted in July 2019. Despite its moderate risk level, Duncan remains a crucial water resource for the local community, supporting various recreational activities and providing habitat for fish and wildlife. Located just 30 miles from Durango, Duncan plays a vital role in water management and conservation efforts in La Plata County.
With state regulation, permitting, inspection, and enforcement in place, Duncan is a well-maintained and regulated water resource. The dam's emergency action plan status, inundation maps, and risk management measures are currently not available, but the dam is equipped with necessary safety features like a spillway and outlet gates to ensure the protection of downstream areas. As a key component of the local water infrastructure, Duncan continues to be a focal point for water resource and climate enthusiasts interested in sustainable water management practices.
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 Duncan -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Animas River Above Tacoma | 1,160 cfs | → |
| Animas River Below Silverton | 590 cfs | → |
| Dolores River Below Rico | 298 cfs | → |
| Mineral Creek At Silverton | 205 cfs | → |
| Animas River At Silverton | 306 cfs | → |
| Cement Creek At Silverton | 53 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Duncan.
Boat launches
Campgrounds
- Purgatory
- Sig Creek Campground
- Sig Creek
- Haviland Lake Campground
- Haviland Lake
- Chris Park Group Campground
Fishing spots
- Haviland Lake
- Andrews Lake Swa
- Elbert Creek
- Lemon Reservoir
- Sheep Corrals Fishing Site
- Vallecito Reservoir
Paddle runs
- South Mineral Creek
- Animas River
- Mineral Creek
- Confluence With Rincon La Vaca And North Fork To Northern Line Of Granite Peak Ranch
- Rincon La Osa--Headwaters To Confluence With Los Pinos
- Lake Creek--Headwaters To Confluence With Los Pinos
More reservoirs
Track Duncan 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 Duncan
Where does the data for Duncan 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 Duncan.