Island Lake, located in Boulder, Colorado, is a concrete gravity dam completed in 1890 primarily for water supply purposes. The dam stands at 18 feet high with a hydraulic height of 23 feet, providing storage for up to 386 acre-feet of water. With a surface area of 35 acres and a drainage area of 5 square miles, the dam regulates the flow of the North Boulder Creek-TR.

Managed by local government authorities and regulated by the Colorado Department of Water Resources, Island Lake has a low hazard potential with a satisfactory condition assessment as of September 2017. The spillway, which is uncontrolled, has a width of 135 feet to release excess water in case of overflow. The dam is inspected every 6 years to ensure its structural integrity and safety for the surrounding community.

Despite its age, Island Lake continues to play a crucial role in water resource management in the region, serving as a reliable source of water supply and contributing to the overall water infrastructure in Boulder County. Climate and water resource enthusiasts will appreciate the historical significance and engineering marvel of this structure, which has been effectively maintained to mitigate potential risks and ensure the safety of the community it serves.