MWH provided construction management services for the L.L. Anderson Dam Spillway Modification Project, an award-winning, heavy civil infrastructure project located within the Tahoe National Forest. The project increased spillway discharge capacity to safely pass the updated Probable Maximum Flood (PMF) without overtopping the dam, protecting downstream communities and critical water and hydropower infrastructure.

The team successfully completed this complex, high-altitude project on schedule and within budget despite severe weather, remote access, and stringent regulatory oversight by FERC and the California Department of Safety of Dams.

Key improvements included precision rock excavation and controlled blasting, construction of a new reinforced concrete spillway control structure with twin 36.5-foot-wide radial gates, extensive shotcrete and rock-bolting for erosion control, seepage cutoff grouting, and a raised dam crest with new parapet walls.

MWH’s proactive partnering, advanced cost and schedule controls, and robust safety and quality management programs resulted in zero recordable incidents, no claims, and completion 10 days ahead of schedule. The project earned recognition as the ASCE California Construction Project of the Year and the CMAA Northern California Project Achievement Award for its innovation, technical excellence, and public safety benefits.

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