Marine Construction on Loch Lomond Inlet/Outlet Replacement Project at Newell Creek Dam, Ben Lomond, CA-Paper

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The City of Santa Cruz replaced the deteriorated inlet/outlet works at Newell Creek Dam, its primary water-storage facility, while keeping the reservoir operational. The $70 million project addressed aging infrastructure and dam-safety requirements, with construction taking place underwater at depths of up to 145 feet and under strict environmental controls.<br /><br />The marine subcontractor’s work included installing a 1,550-foot turbidity curtain, dredging about 25,000 cubic yards of rock and sediment, and constructing three inlet foundations, shafts, debris walls, and inlet assemblies. Crews also installed supports and roughly 600 feet of vent line along the reservoir floor. Work relied on barges, divers, remotely operated vehicles, multi-beam sonar, and specialized drilling and placement equipment. On-site precasting and a launchway enabled large foundation units to be moved into position despite the remote location and variable water levels.<br /><br />The team addressed underwater visibility, precision, access, and alignment challenges through continuous surveys, diver communications, and carefully engineered installation systems. Contractor-proposed design adjustments—including revised vent-line supports and routing—reduced dredging and support requirements and helped resolve final fit-up issues.<br /><br />The project began amid a major wildfire and the COVID-19 pandemic. The authors credit structured partnering, open communication, and collaboration between the owner, designers, and contractors with resolving problems and improving project value. The work was completed on schedule and within budget, with no claims or lost-time injuries.

Keywords

Santa Cruz

Newell Creek Dam

water-storage facility

inlet/outlet works

dam safety

underwater construction

turbidity curtain

dredging

marine subcontractor

project collaboration