Johnston is a privately-owned dam located in Littleton, Colorado, along the Lilley Gulch river. Completed in 1974, this earth dam stands at a height of 11 feet with a hydraulic height of 17 feet, serving primarily for irrigation purposes. With a storage capacity of 1134 acre-feet and a surface area of 82 acres, Johnston plays a crucial role in water resource management in the region.

Maintained by the Colorado Department of Water Resources, Johnston has a significant hazard potential but is currently assessed to be in satisfactory condition as of February 2020. The dam has a moderate risk level, with regular inspections conducted every two years to ensure its safety and functionality. Despite its age, Johnston continues to provide vital water resources for irrigation and recreational activities in the area.

With its uncontrolled spillway and a maximum discharge of 3650 cubic feet per second, Johnston remains an important infrastructure for water management in Jefferson County, Colorado. As climate change continues to impact water resources, the maintenance and regulation of dams like Johnston are essential to ensure the sustainable use of water for agricultural and recreational purposes in the region.