Cottage Grove Dam
Cottage Grove Dam is an earth dam located in Lane County, Oregon, built in 1942. It carries a High hazard potential classification.
About Cottage Grove Dam
The primary purpose of Cottage Grove Dam is flood risk reduction. The dam is designed to control downstream flooding by temporarily storing excess water during storms and releasing it at a controlled rate. The dam is owned by Usace - Portland District (federal). It impounds the Coast Fork Willamette River near Cottage Grove.
The dam stands 103 feet tall and stretches 2,110 feet across, creates a reservoir covering 1,158 acres, has a maximum storage capacity of 50,000 acre-feet, and collects water from a drainage area of 104 square miles. Completed in 1942, the structure is well-established, with more than 75 years of service.
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 04/19/2022.
At 103 feet, this dam is taller than 98% of all dams in the United States.
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 Oregon 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 | Oregon |
| County | Lane |
| Nearest City | Cottage Grove |
| River/Stream | Coast Fork Willamette River |
| Coordinates | 43.71638, -123.05375 |
Physical Characteristics
| Dam Type | Earth |
| NID Height | 103 ft |
| Dam Height | 81 ft |
| Dam Length | 2,110 ft |
| Year Completed | 1942 (84 years old) |
Storage & Hydraulics
| NID Storage | 50,000 acre-ft |
| Max Storage | 50,000 acre-ft |
| Normal Storage | 33,000 acre-ft |
| Surface Area | 1,158 acres |
| Drainage Area | 104 sq mi |
| Max Discharge | 40,800 cfs |
| Spillway Type | Uncontrolled |
Ownership & Safety
| Purpose | Flood Risk Reduction |
| Owner | USACE - Portland District |
| Owner Type | Federal |
| Hazard Classification | High |
| Condition Assessment | Not Available |
| Last Inspection | 04/19/2022 |
| Emergency Action Plan | Yes |
Identifiers
| NID ID | OR00005 |
| Federal ID | OR00005 |
| More Info | State Dam Safety Program |