PG&E is rebuilding the spillway on a 95-year-old dam in the Sierra foothills, and Granite Construction has the $50 million job. The Tiger Creek Regulator Dam sits near Pioneer in Amador County, part of the utility’s Mokelumne River hydroelectric system, and the work covers a full replacement of the crest structure and chute.
Project Scope
Tiger Creek Regulator is a slab-and-buttress dam, originally constructed in 1931. The type is efficient with concrete and unforgiving about spillway performance: water leaving the crest has to be controlled cleanly or it undercuts the structure it’s supposed to protect. Replacing a crest structure and chute on a dam of that age means demolition against a live water-control asset, staged diversion, and new concrete that has to tie into 1930s work whose as-builts are, generously, incomplete.
Access is the other half of the problem. Foothill hydro sites are reached by narrow service roads, and haul routes for concrete, rebar and demolition spoil constrain both crew size and pour sequencing. Work windows on Sierra hydro projects are typically driven by the runoff calendar rather than the calendar year.
Granite self-performs heavy civil concrete work, which is the reason this scope suits it. The contract lands as the firm reports a record $7.4 billion backlog and leans further into water infrastructure.
Why It Matters
Dam safety spending has become one of the more reliable heavy-civil markets in the West, and utilities own a large share of the aging inventory. California has more than 1,200 jurisdictional dams, and a meaningful portion of the hydro fleet predates 1950. Regulators have tightened spillway standards considerably since the 2017 Oroville failure, when a hole opened in the main concrete chute and forced 188,000 people to evacuate. Every spillway of a certain vintage has been re-examined against that event.
The economics are straightforward for a utility: a spillway rebuild is a fraction of what a decommissioning or a failure costs, and it preserves generation. Expect more of these. The bid list is short, though. There are only so many contractors with the concrete self-perform capacity and the appetite for remote foothill logistics, which keeps pricing firmer here than in flatland civil work.
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Project Team & Details
| Owner / Client | Pacific Gas and Electric Company |
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| General Contractor | Granite Construction |
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| Status | Planned |
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| Funding Source | Private |
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