Main dam
Main
Main, also known as Big Osner, is a private water resource located in Jefferson County, Colorado. Built in 1908 for irrigation purposes, this Earth-type dam stands at a height of 45 feet and has a storage capacity of 1320 acre-feet. With a spillway width of 60 feet and a maximum discharge of 700 cubic feet per second, Main plays a crucial role in managing water flow and storage in the region.
The dam is state-regulated by the Colorado Department of Water Resources, ensuring that it is regularly inspected, maintained, and enforced for safety and compliance. Despite its high hazard potential, Main has been assessed as satisfactory in condition, with a moderate risk level of 3. Additionally, the dam has a history of being updated and meeting regulatory guidelines, showcasing a commitment to responsible water management and risk mitigation in the face of changing climate patterns and water resource challenges.
Located in Lakewood, Main serves not only for irrigation but also for recreational purposes, highlighting its multi-functional role in the community. With its historical significance and essential contribution to water supply and management, Main stands as a testament to the importance of sustainable water resource practices in the face of climate variability and increasing water demands.
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 Main -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Bear Creek Above Bear Creek Lake Near Morrison | 4 cfs | → |
| Bear Creek At Morrison | 16 cfs | → |
| Bear Creek At Mouth | 8 cfs | → |
| South Platte River At Englewood | 32 cfs | → |
| South Platte River Below Union Ave | 23 cfs | → |
| Cherry Creek At Denver | 39 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Main.
Boat launches
- Fisherman's Trail Lakewood
- C-470 Trail Lakewood
- West Quincy Avenue Denver
- West 69th Avenue 4700, Westminster
- Chatfield Lake North Boat Ramp
- Ralston Creek Trail Arvada
Campgrounds
- Bear Creek Lake Park
- Clear Creek Rv Park
- Gennessee Ropes Camp Spot
- Chatfield State Park
- Standley Lake
- Tipi Village
Fishing spots
- Main Reservoir
- East Reservoir
- Smith Reservoir (Lakewood)
- Kendrick Reservoir
- Cottonwood Park Lake (Kipling & Jewell)
- Union Square Ponds
Track Main 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 Main
Where does the data for Main 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 Main.