Lake Wilhelm (Pa-475) dam
Lake Wilhelm (Pa-475)
Lake Wilhelm (Pa-475) in Mercer, Pennsylvania, is a state-regulated reservoir designed by the USDA NRCS for flood risk reduction along Sandy Creek. Completed in 1969, this earth dam stands at 50 feet in height and spans 500 feet in length, with a storage capacity of 66,400 acre-feet and a surface area of 1680 acres. The primary purpose of Lake Wilhelm is flood risk reduction, with secondary benefits including recreation opportunities for the surrounding community.
Managed by the Pennsylvania Department of Environmental Protection, Lake Wilhelm has a high hazard potential but is currently in satisfactory condition, as assessed during the last inspection in September 2020. The reservoir boasts a drainage area of 56.5 square miles and is a vital resource for water supply and flood control in the region. With its strategic location and effective design, Lake Wilhelm serves as a key component of the local water resource infrastructure, ensuring the safety and well-being of nearby residents during extreme weather events.
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 Lake Wilhelm (Pa-475) -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| French Creek At Utica | 1,670 cfs | → |
| Allegheny River At Franklin | 10,200 cfs | → |
| Little Shenango River At Greenville | 116 cfs | → |
| Shenango River Near Transfer | 438 cfs | → |
| French Creek At Meadville | 1,310 cfs | → |
| Shenango River At Sharpsville | 480 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Wilhelm (Pa-475).
Track Lake Wilhelm (Pa-475) 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 Lake Wilhelm (Pa-475)
Where does the data for Lake Wilhelm (Pa-475) 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 Lake Wilhelm (Pa-475).