Somerville-Mccullah, also known as Somerville #1, is a vital irrigation structure located in Mesa County, Colorado. Built in 1972, this earth dam stands at a height of 42 feet and serves multiple purposes including fire protection, stock, small fish pond, irrigation, and water supply. With a storage capacity of 1364 acre-feet, the dam covers a surface area of 75 acres and has a maximum discharge of 900 cubic feet per second.

Managed by the local government and regulated by the Colorado Division of Water Resources, Somerville-Mccullah plays a crucial role in water resource management in the region. Despite being rated as having a high hazard potential, the dam's condition is assessed as fair, with regular inspections conducted to ensure its safety and functionality. The spillway, outlet gates, and uncontrolled spillway type are designed to handle emergency situations, showcasing the dam's preparedness for unforeseen events.

Situated along the Whitewater Creek in Grand Junction, Somerville-Mccullah is a significant infrastructure that not only supports agricultural activities but also contributes to the overall water supply in the area. Its risk assessment is moderate, indicating the need for continued monitoring and risk management measures to safeguard it against potential threats. As a key component of the local water management system, this dam remains a critical asset for the community and a focal point for water resource and climate enthusiasts.