Sinlahekin Dam No 3 dam
Sinlahekin Dam No 3
Sinlahekin Dam No 3, also known as Conners Lake, is a state-owned structure located in Loomis, Washington, along the Sinlahekin Creek. Built in 1950 by URS-Woodward Clyde, this earth dam stands at a hydraulic height of 24 feet and a structural height of 22 feet, with a length of 285 feet. The dam serves primarily for recreational purposes, providing a storage capacity of 593 acre-feet and a surface area of 211 acres.
The dam is regulated by the Washington Department of Ecology and undergoes regular inspections, with the last assessment conducted in 2016. Despite its high hazard potential, the condition of Sinlahekin Dam No 3 is deemed satisfactory. Emergency action plans are in place but may require updates to meet current guidelines. The dam's risk assessment and management measures are currently unspecified, highlighting the importance of ongoing monitoring and maintenance to ensure its safety and functionality for water resource and climate enthusiasts in the region.
Overall, Sinlahekin Dam No 3 plays a vital role in providing recreational opportunities while also serving as a crucial infrastructure for water management in Okanogan County, Washington. Its historical significance, coupled with its ongoing regulatory oversight and maintenance efforts, underscore the importance of sustainable practices in safeguarding water resources and addressing climate-related challenges 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 Sinlahekin Dam No 3 -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Okanogan River Near Tonasket | 5,120 cfs | → |
| Similkameen River Near Nighthawk | 4,950 cfs | → |
| Okanogan River At Oroville | 164 cfs | → |
| Andrews Creek Near Mazama | 107 cfs | → |
| Omak Creek Near Omak | 3 cfs | → |
| Methow River At Winthrop | 2,740 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Sinlahekin Dam No 3.
Boat launches
- Windy Flat Road Okanogan County
- Split Rock
- Loomis-Oroville Road 1667, Loomis
- Loomis-Oroville Road 322, Tonasket
- Sinlahekin Road Okanogan County
- South Fish Lake Road, Okanogan
Campgrounds
- Conners Lake - Wdfw
- Conners Lake
- Forde Lake - Wdfw
- Forde Lake
- Sinlahekin Wildlife Area
- Sinlahekin Creek - Wdfw
Track Sinlahekin Dam No 3 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 Sinlahekin Dam No 3
Where does the data for Sinlahekin Dam No 3 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 Sinlahekin Dam No 3.