Antilon Lake Dam dam
Antilon Lake Dam
Antilon Lake Dam, located in Manson, Washington, is a public utility dam primarily used for recreation purposes. Completed in 1913, this earth dam stands at a hydraulic height of 62 feet, with a structural height and NID height also at 62 feet. The dam has a length of 300 feet and a storage capacity of 2475 acre-feet, providing ample space for recreational activities on its 118-acre surface area.
Managed by the Washington Department of Ecology, Antilon Lake Dam is state-regulated and inspected regularly to ensure its safety and satisfactory condition. With a high hazard potential, the dam is equipped with emergency action plans to mitigate any risk of failure. The last inspection in November 2018 deemed the dam to be in satisfactory condition, with an inspection frequency of every 5 years. In case of an emergency, the dam is equipped with updated emergency contacts and guidelines to meet safety standards.
The dam's location along Tr-Johnson Creek in Chelan County, Washington, makes it a vital water resource for the region. With a maximum discharge of 360 cubic feet per second, the dam plays a crucial role in managing water flow and storage in the area. As a popular spot for outdoor enthusiasts, Antilon Lake Dam serves as a recreational oasis while also serving as a critical infrastructure for water resource management in the region.
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 Antilon Lake Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| Methow River Near Pateros | 783 cfs | → |
| Chelan River At Chelan | 186 cfs | → |
| Entiat River Near Ardenvoir | 186 cfs | → |
| Mad River At Ardenvoir | 26 cfs | → |
| Entiat River Near Entiat | 219 cfs | → |
| Chiwawa River Near Plain | 265 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Antilon Lake Dam.
Boat launches
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Campgrounds
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Fishing spots
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River runs
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About Antilon Lake Dam
Where does the data for Antilon Lake Dam 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 below 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.
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.