Hallenbeck #1, also known as Purdy Mesa, is a vital water resource infrastructure located in Mesa, Colorado. This earth dam was completed in 1970 and serves multiple purposes, including water supply and recreation. With a height of 41 feet and a storage capacity of 1155 acre-feet, Hallenbeck #1 plays a crucial role in managing water resources in the region.

Owned by a local government entity, Hallenbeck #1 is regulated by the Colorado Department of Water Resources and undergoes regular inspections to ensure its structural integrity. The dam has a spillway width of 30 feet and is equipped with slide and uncontrolled gates for water release. Despite being classified as having a high hazard potential, the dam is assessed to be in fair condition as of April 2020, with a moderate risk rating.

Situated on the Kahnah Creek-TR river system and managed by the Omaha District of the US Army Corps of Engineers, Hallenbeck #1 stands as a significant piece of infrastructure for water supply and management in the Whitewater area. With its strategic location and functionality, this dam continues to play a vital role in the overall water resource management efforts in Colorado.