| James J. Lenihan Dam | |
| Name Official: | Lexington Dam |
| Dam Crosses: | Los Gatos Creek |
| Res Name: | Lexington Reservoir |
| Location: | Santa Cruz Mountains Santa Clara County, California |
| Dam Length: | 810feet |
| Dam Height: | 208feet |
| Dam Width Base: | 40feet |
| Res Capacity Total: | 21430acre.ft |
| Res Catchment: | 27.7sqmi |
| Res Surface: | 450acres |
| Coordinates: | 37.202°N -121.988°W |
James J. Lenihan Dam is an earthen structure across the Los Gatos Creek creating the Lexington Reservoir in the Santa Cruz Mountains of Santa Clara County, California south of Los Gatos. The name was changed from Lexington Dam in 1996 for the retirement of James J. Lenihan, the Santa Clara Valley Water District's longest-serving director.