Lake Ann, also known as Dinkle Lake, is a private reservoir located in Pitkin County, Colorado, near the city of El Jebel. The dam, completed in 1912 and designed by BOND Engineering, stands at a height of 40 feet and serves primarily for irrigation purposes. With a storage capacity of 562 acre-feet, the reservoir covers an area of 20 acres and is fed by the West Sopris Creek.

Despite its age, Lake Ann has been regularly inspected and maintained by the Colorado Department of Water Resources (DWR), with a fair condition assessment as of July 2020. The dam's spillway, an uncontrolled type with a width of 40 feet, has a high hazard potential but is considered to have a moderate risk level. The reservoir's emergency action plan (EAP) was last revised in December 2015, and the facility is equipped with a slide (sluice gate) outlet gate for water release.

Lake Ann offers not only essential irrigation functions but also recreational opportunities for the local community. With its picturesque location and historical significance, this reservoir serves as a vital water resource in the region while maintaining a balance between water management and environmental preservation.