Lon Hagler is a privately owned dam located in Larimer County, Colorado, along the Big Thompson River. Constructed in 1967 by the USDA NRCS, this earth dam stands at a height of 60 feet and has a storage capacity of 6,275 acre-feet. The primary purpose of Lon Hagler is irrigation, but it also serves recreational purposes, covering a surface area of 201 acres.

Managed by the Colorado Department of Water Resources, Lon Hagler is regulated and inspected regularly to ensure its safety and compliance with state regulations. The dam has a high hazard potential and is classified as satisfactory in terms of condition assessment. Despite its age, Lon Hagler has undergone no significant modifications over the years, indicating its structural stability.

With a spillway width of 30 feet and a maximum discharge capacity of 920 cubic feet per second, Lon Hagler plays a crucial role in water resource management in the region. The dam's location in Loveland, Colorado, under the jurisdiction of the Omaha District, highlights its significance in providing irrigation water and recreational opportunities while ensuring public safety and environmental protection.