Rehmer, also known as Arrowhead, is a privately owned irrigation dam located in La Salle, Weld County, Colorado. Completed in 1957, this earth dam stands at a height of 23 feet and has a structural height of 28 feet, with a length of 313 feet. The dam serves the primary purpose of irrigation, with a storage capacity of 45 acre-feet and a maximum discharge of 788 cubic feet per second.

Situated on the Big Thompson River, Rehmer is regulated by the Colorado Division of Water Resources and is subject to state permitting, inspection, and enforcement. Despite being classified as having a low hazard potential, the dam is rated as satisfactory in condition assessment and has a moderate risk level. The spillway type is uncontrolled, with a width of 45 feet, and the dam has a surface area of 5 acres. The last inspection was conducted in January 2017, with an inspection frequency of every 6 years.

Overall, Rehmer serves as a vital component of the irrigation infrastructure in the region, providing water resources for agricultural purposes. With its strategic location on the Big Thompson River, this dam plays a crucial role in water management and conservation efforts in Weld County, Colorado. The satisfactory condition assessment and moderate risk level reflect the ongoing maintenance and monitoring efforts to ensure the safety and functionality of the structure for the surrounding area.