Mulligan, also known as Red Deer, is a private dam located in Weld County, Colorado, specifically in the city of Platteville. Completed in 1878 for recreational purposes, this earth dam stands at a height of 10 feet and stretches 700 feet in length. It has a storage capacity of 84 acre-feet, with a normal storage level of 51 acre-feet and a surface area of 13 acres.

Despite its age, Mulligan's hazard potential is rated as low, with a moderate risk assessment of 3. The dam is state-regulated and inspected, meeting all necessary permitting and enforcement requirements. The spillway, although uncontrolled, has a width of 100 feet to manage potential floods effectively. Interestingly, the dam has not been modified in recent years, highlighting its enduring structural integrity and safety standards.

Overall, Mulligan represents a historic and well-maintained water resource in Colorado, providing vital recreational opportunities while ensuring public safety and environmental protection. Its location along the St. Vrain Creek-OS adds to the scenic beauty of the area, making it a valuable asset for both water enthusiasts and climate conservationists to appreciate and enjoy.