Officials in California are moving forward with plans to construct the 1.5-million-acre-ft Sites Reservoir in the Sacramento Valley. The Sites Project Authority, which is leading the project, issued a request for qualifications Jan. 9 for a construction manager at-risk for the estimated $3-billion reservoir and roads package.

The project scope includes construction of two main dams, the Sites Dam on Stone Corral Creek and Golden Gate Dam on Funks Creek, which would each be about 270 ft high, with bases about 1,300 ft wide, records show. It also includes seven saddle dams and three dikes, ranging from 6 ft to 107 ft in height. 

Additionally, the contractor would be responsible for building a concrete overflow spillway on the north side of the reservoir rim; an inlet/outlet works with a 32,00 linear ft, 24.5-ft excavated dia tunnel that would connect to downstream infrastructure to be built via a separate construction package; a diversion outlet with a 14.5-ft interior dia steel-lined tunnel running 1,320 linear ft. The scope also includes construction of two bridges, one 1,900 ft long and the other 2,700 ft long, plus widening a combined 7.2 miles of road.

Responses to the RFQ are due by March 10. The Sites Project Authority aims to select a shortlisted firm for an initial preconstruction services contract in the fall, for work to start next year. The authority anticipates construction completion by the end of 2032. 

Separately, the authority also issued a request for proposals seeking a construction office lead. Responses to the RFP are due Feb. 3. 

The reservoir will add storage capacity to improve water reliability and resiliency of water infrastructure and to better capture water from storms in line with future climate projections as the West becomes drier. Water will be drawn from the reservoir during periods of drought.

While the plan calls for construction of dams, the reservoir would be off-stream, and no rivers would be impeded. The reservoir would be fed by rain and stormwater from the Sacramento River at the existing Red Bluff Pumping Plant and Hamilton City Pump Station only during high flows.

“As one of the largest water infrastructure projects currently under development in California, Sites is a significant opportunity to enhance water reliability for the benefit of our communities, farms and environment,” said Fritz Durst, chair of the Sites Project Authority board of directors, in a statement. 

The authority was formed in 2010 to lead development of the reservoir project. Another 30 local, state and federal agencies are also participating. 

Located about 65 miles northwest of Sacramento, the filled reservoir would measure about 13 miles long north-south, 4 miles wide east-west and 260 ft deep. It would be California’s eighth-largest reservoir, capable of holding enough water to serve 7.5 million people for a year, according to the authority.