Blackmer #1 is a privately owned irrigation dam located in Arapahoe County, Colorado, along the South Platte River. Built in 1936, this earth dam stands at a height of 12 feet and has a hydraulic height of 8 feet, with a length of 488 feet. The dam serves primarily for irrigation purposes, with a storage capacity of 69 acre-feet and a normal storage of 37 acre-feet.

Despite being classified as having a low hazard potential, Blackmer #1 underwent a satisfactory condition assessment in 2016. The dam features an uncontrolled spillway with a width of 67 feet and has a maximum discharge of 2000 cubic feet per second. While the risk assessment for the dam is moderate, there are no specific risk management measures or emergency action plans in place as of the last inspection date in 2016.

For water resource and climate enthusiasts, Blackmer #1 offers an intriguing case study of an early 20th-century irrigation structure in Colorado. Its location on the South Platte River and its role in water management make it a significant piece of the region's hydrological landscape. As discussions around dam safety and risk management continue, Blackmer #1 serves as a reminder of the importance of maintaining and monitoring critical infrastructure in the face of changing environmental conditions.