Newell Creek Dam (NCD) is a 195-foot-high earth-fill dam constructed in 1961 impounding Loch Lomond Reservoir. The dam is operated by the Santa Cruz Water Department and regulated by the California Department of Water Resources Division of Safety of Dams (DSOD).
Loch Lomond Reservoir is the City of Santa Cruz's only surface water storage facility and a critical component of the City’s permitted drinking water system. The existing NCD inlet/outlet works consist of a 24-inch sloping intake pipe on the dam face with five inlets and hydraulic system to operate the valves at each inlet; a 36-inch conduit under the dam; a 30-inch conduit connecting the 24-inch intake pipe and 36-inch conduit; and release facilities at the dam toe including the connection to the Newell Creek Pipeline (NCP) and the valves for making emergency and beneficial releases to Newell Creek.  

Identified deficiencies indicate the existing NCD inlet/outlet works is approaching the end of its useful design life. Future failure of the existing inlet/outlet works would eliminate the City’s ability to provide drinking water to its customers during dry summer months when other sources cannot meet demand and during winter when other sources are too turbid due to storm runoff.

The NCD I/O Project will replace the aging NCD inlet/outlet works in a new location. The proposed improvements will furthermore improve the City’s overall operational efficiency, improve system performance, and provide for long-term reliable storage for the City’s drinking water supply. 

Project Objectives

  • Protect the City's water supply system by addressing existing deficiencies.
  • Establish long-term reliable storage of drinking water supply.
  • Meet DSOD drawdown requirements.
  • Improve overall operational efficiency and system performance.
  • Improve inspection and maintenance access.
  • Implement a cost-effective project, including operation/maintenance costs.
  • Maintain uninterrupted beneficial flow releases during construction.

Project Components

  • Three new inlets that control and convey flows.
  • New outlet structure with valves and controls to provide for energy dissipation for water releases to the Newell Creek Pipeline (NCP) or beneficial releases to Newell Creek.
  • New dam seepage collection and monitoring system.
  • 10-14 foot diameter tunnel with 48-inch and 10-inch inlet/outlet pipelines.
  • Replacement of approximately 2,000 linear-foot segment of the NCP.
  • New intake control building on dam crest.
  • Access road improvements including a new culvert crossing at spillway plunge pool.
  • Decommissioning the existing inlet/outlet works.

Thanks for Building!

Alliant would like to say #thanksforbuilding to Obayashi who continues to contribute to the development of our nation's safety, infrastructure, facilities and economy. Obayashi’s North American Civil Group, located in Burlingame, CA, manages heavy civil construction projects; tunnels, bridges, dams, highway, and other infrastructure works throughout the United States and Canada.


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