Rainbow Lake, also known as Mt Yale Reservoir, is a private water resource located in Chaffee County, Colorado, near the city of Buena Vista. Built in 1965, this rockfill dam stands at a height of 23 feet and has a storage capacity of 196 acre-feet, primarily serving recreational purposes such as fishing and wildlife preservation. With a surface area of 19 acres and a drainage area of 32 square miles, Rainbow Lake is fed by the Middle Cottonwood River and boasts a maximum discharge of 1730 cubic feet per second.

Despite its low hazard potential and satisfactory condition assessment, Rainbow Lake is subject to state regulation and inspection by the Colorado Division of Water Resources. The reservoir's uncontrolled spillway, with a width of 61 feet, ensures the safe release of excess water during periods of high flow. Its emergency action plan status and risk assessment indicate a moderate level of risk, with measures in place to mitigate potential hazards. While the dam has not been significantly modified since its construction, regular inspections every six years help to ensure its continued safety and reliability for the surrounding community and ecosystem. Overall, Rainbow Lake stands as a vital water source and recreational haven in the heart of Colorado's scenic landscape.