Lake Lancelot Dam
Lake Lancelot Dam is an earth dam located in Peoria County, Illinois, built in 1971. It carries a High hazard potential classification.
About Lake Lancelot Dam
The primary purpose of Lake Lancelot Dam is recreation. The dam creates a reservoir used for recreational activities such as fishing, boating, and swimming. The dam is owned by Camelot Round Table Association (private). It impounds the Trib West Branch Lamarsh Creek near Mapleton-offstream.
The dam stands 54 feet tall and stretches 750 feet across, creates a reservoir covering 48 acres, has a maximum storage capacity of 1,271 acre-feet, and collects water from a drainage area of 2 square miles. Completed in 1971, the structure is well into its service life at over 50 years old.
This dam carries a high hazard potential classification, which means that a failure or uncontrolled release of water would likely cause loss of human life. This classification reflects the consequences of failure, not the likelihood — it indicates that people live or work in the area downstream. An emergency action plan is in place for this dam. The most recent inspection on record was 02/27/2026.
At 54 feet, this dam is taller than 94% of dams nationwide.
Living Downstream
If you live or work downstream of this dam, consider taking these steps: learn your local evacuation routes, check whether your county emergency management office has a dam failure inundation map, and sign up for local emergency alerts. The Illinois dam safety program can provide more specific information about emergency planning for this structure.
Search for dams near your address to see all dams in your area with hazard classifications and safety data.
Location
| State | Illinois |
| County | Peoria |
| Nearest City | Mapleton-offstream |
| River/Stream | Trib West Branch Lamarsh Creek |
| Coordinates | 40.62858, -89.74175 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 54 ft |
| Dam Height | 54 ft |
| Dam Length | 750 ft |
| Year Completed | 1971 (55 years old) |
Storage & Hydraulics
| NID Storage | 1,271 acre-ft |
| Max Storage | 1,271 acre-ft |
| Normal Storage | 654 acre-ft |
| Surface Area | 48 acres |
| Drainage Area | 2 sq mi |
| Max Discharge | 2,315 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Recreation |
| Owner | CAMELOT ROUND TABLE ASSOCIATION |
| Owner Type | Private |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 02/27/2026 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | IL01147 |
| Federal ID | IL01147 |
| More Info | State Dam Safety Program |