Flatiron, also known as Afterbay, is a federal-owned dam located in Larimer County, Colorado. Constructed in 1953 by the Bureau of Reclamation, this earth dam stands at a height of 86 feet, with a primary purpose of hydroelectric generation and irrigation. With a storage capacity of 1,136 acre-feet, Flatiron serves as a crucial water resource for the region.

Situated on Dry Creek-Tr and Chimney Hollow Creek, Flatiron plays a key role in managing water flow and storage in the area. The dam has a surface area of 381,500 square feet and drains an area of 7.42 square miles. Despite its high hazard potential, with a risk assessment rating of 2, Flatiron is regulated and inspected by the Bureau of Reclamation to ensure its structural integrity and safety.

For water resource and climate enthusiasts, Flatiron represents a significant infrastructure for water management in Colorado. With its hydroelectric capabilities and role in irrigation, this dam serves as a vital component of the region's water supply system. As a federally-owned and regulated structure, Flatiron plays a crucial role in safeguarding the surrounding communities from water-related risks and emergencies.