Colorado-Big Thompson Project

The Colorado-Big Thompson Project (C-BT) is a major water diversion project in Northern Colorado, designed to provide water for agricultural, municipal, and industrial use. Spanning across the continental divide, it collects and distributes water from the Colorado River's headwaters on the Western Slope to the arid Eastern Slope. The project includes a series of reservoirs, tunnels, pipelines, and powerplants that collectively move water across the divide. Key features include the Alva B. Adams Tunnel, which runs beneath Rocky Mountain National Park, and Lake Granby, one of the main storage reservoirs. The C-BT not only supports local agriculture but also provides recreation opportunities such as fishing and boating. Its historical significance dates back to the 1930s when it was developed in response to water shortages and growing demand in the region. Today, the project supports over 1 million residents and irrigates hundreds of thousands of acres.