The Sites Reservoir Project, located in Northern California, is under development as one of the largest water supply projects to date in California, with an expected cost of over $6 billion. 

Proponents say that this project's development to improve California's water supply system and provide an increased amount of water to assist with drought caused by climate change is critical.

The project will be created by constructing a new off-stream reservoir in Colusa County, California, just to the West of Maxwell, California. 

This off-stream reservoir will provide the capability of storing excess river flows (primarily from the Sacramento River) during wet years to use during times of drought or excess demands on California's water supply. When completed, the storage volume of the Sites Reservoir will be approximately 1.5 million acre-feet, which will make the Sites Reservoir one of the largest water storage projects built in California in almost 50 years.

Further announcements about the development of the Sites Reservoir were made when Barnard Construction Company was selected to execute a pre-construction planning contract with the project owners. 

The "Construction Manager At Risk" model was chosen for the execution of the contract, reflecting the desire of the project owners to include early involvement from the contractor to develop a better understanding of project cost factors, schedule considerations, and constructability for a project of this scale and level of technical complexity.

California's water agencies and agriculture districts have historically placed importance on increasing their water storage capacity in order to deal with changing and increasing climate volatility that results in cycles of flooding followed by prolonged droughts. New studies show how Sites Reservoir will become a key element in California's long-term water solutions by increasing reliability to urban consumers, agricultural producers, and the required environmental flows.

For contractors, engineers, and manufacturers, this is a very rare multi-year mega project that includes several dams, embankments, roads, pumping systems, and other civil works. The last estimate placed Northern California's reservoir initiative at $6.2 billion, confirming the magnitude of public support for the overall construction of these facilities.

The construction of Sites Reservoir is going to add to California's overall water supply and ultimately California's financial commitment to numerous principal capital projects. State officials are projecting $180 billion of infrastructure expenditures for building projects that are either transportation, water, or public works-based throughout California. Thereby indicating a present and future need for the development of large civil construction projects.