Lake Mendota Dam dam
Lake Mendota Dam
Lake Mendota Dam, located in Mendota, Illinois, serves as a crucial structure for the management of Mendota Creek. Built in 1890, this Earth-type dam stands at a height of 17 feet and stretches over 2430 feet in length, providing a storage capacity of 246 acre-feet. While primarily designed for recreational purposes, the dam also plays a key role in regulating water flow and ensuring flood control in the area.
With a high hazard potential and a very high risk assessment rating, Lake Mendota Dam is closely monitored and inspected by the Illinois Department of Natural Resources. Despite its age, the dam has not undergone any recent modifications, and its condition assessment is currently listed as not available. The dam's controlled spillway and other controlled outlet gates help manage water levels and ensure the safety of the surrounding community in the event of an emergency.
As a significant landmark in LaSalle County, Illinois, Lake Mendota Dam stands as a testament to the engineering feats of the past and the ongoing importance of water resource management in the face of changing climate patterns. Its role in recreation, flood control, and water regulation underscores the critical need for continued monitoring and maintenance to ensure the safety and resilience of this vital infrastructure for years to come.
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 Mendota Dam -- inflows here typically show up in storage 24-72 hours later.
| Streamgauge | Discharge | View |
|---|---|---|
| East Bureau Creek Near Bureau | 2 cfs | → |
| Fox River At Dayton | 1,700 cfs | → |
| Big Bureau Creek At Princeton | 50 cfs | → |
| Vermilion River Near Leonore | 487 cfs | → |
| Illinois River At Marseilles | 5,340 cfs | → |
| South Branch Kishwaukee River At Dekalb | 35 cfs | → |
Make a day of it
Boat launches, lakeside camping, fishing access, and other reservoirs near Lake Mendota Dam.
Boat launches
- Il 89 Spring Valley
- Ed Hand Highway 95, Deer Park
- Tomahawk Trail Dekalb County
- Il 71 Lasalle County
- Courtney Street Ottawa
- Calumet Street Ottawa
Campgrounds
- Starved Rock State Park
- Horseback Campground @ Matthiessen State Park
- Lake De Pue City Park
- Green River State Wildlife Area
- Illini State Park
- Illini State Park Campground
Track Lake Mendota Dam 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 Mendota Dam
Where does the data for Lake Mendota 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 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 Mendota Dam.