| Dayton Hollow Dam | |
| Coordinates: | 46.2308°N -96.1175°W |
| Purpose: | Hydro Power Fish & Wildlife Pond |
| Status: | In use |
| Construction Began: | 1907 |
| Opening: | 1909 |
| Owner: | Otter Tail Power Company |
| Dam Type: | G |
| Dam Crosses: | Otter Tail River |
| Dam Height Foundation: | NaN41 |
| Dam Length: | NaN256 |
| Spillway Count: | 1 |
| Spillway Type: | 7 controlled sluice gates |
| Spillway Capacity: | NaN2000 |
| Res Name: | Dayton Hollow Reservoir |
| Res Capacity Total: | NaN5000 |
| Res Catchment: | NaN1810 |
| Res Elevation: | NaN1073[1] |
| Plant Type: | C |
| Plant Hydraulic Head: | NaN36 |
| Plant Turbines: | 3 |
| Plant Capacity: | 1.0 MW |
| Extra: | NIDID# MN00196 |
Dayton Hollow Dam is a hydroelectric gravity dam on the Otter Tail River in Otter Tail County, Minnesota in the United States. It is located 5 miles southwest of the city of Fergus Falls. Completed in 1909, it is the first power plant built by the Otter Tail Power Company and is one of five dams on the river. Together, they produce about 3.5 megawatts of power.
Shortly after becoming operational, Dayton Hollow Dam narrowly avoided destruction. The city-owned Fergus Falls City Light Station, several miles upstream, abruptly failed in the early hours of September 24, 1909. Three other dams between the disaster site and Dayton Hollow were swept away and a fourth (Central / Wright) was badly damaged. Otter Tail Power Company president Vernon Wright received enough advance warning to reach his dam by 6:15am and open the spillway. The only flood recorded in the history of the river was due to this disaster.
The license for the hydroelectric plant expires on November 30, 2021. In June 2016 the company filed a pre-application with the Federal Energy Regulatory Commission to re-license the station with no changes to existing facilities or operations. The process will take 5 years.