Risk-Informed Decision-Making at Union Valley Dam

Union Valley Dam, a 453-foot-high earthfill embankment owned by the Sacramento Municipal Utility District (SMUD), plays a vital role in water management and hydroelectric power east of Sacramento, California. As part of the Federal Energy Regulatory Commission (FERC) 10-year comprehensive review process, SMUD completed a comprehensive assessment in 2023. This analysis identified top risk contributors, each carrying significant uncertainty due to limitations in available data. SMUD needed a transparent, defensible strategy to prioritize risk reduction efforts while navigating uncertainty, regulatory complexity, and public safety.

GFT is leading a targeted risk assessment using FERC’s risk-informed decision-making (RIDM) framework, an approach that integrates quantitative risk data with expert judgment, operational context, and uncertainty analysis. Unlike purely risk-based decision-making, which ranks hazards numerically, RIDM balances risk data, engineering experience, uncertainty analysis, and practical design thresholds to guide decisions that make the dam as safe as realistically and economically possible.

In collaboration with FERC, the California Division of Safety of Dams, the U.S. Army Corps of Engineers, Sacramento Area Flood Control Agency, and the Bureau of Reclamation, our team is evaluating all credible potential failure modes and developing a suite of actionable risk reduction measures. These include structural modifications, emergency planning enhancements, and further analytical studies. We will combine these into implementable risk reduction alternatives, giving SMUD a strategic path forward to reducing uncertainty, enhancing dam safety, and aligning with regional standards.

The project demonstrates how RIDM empowers dam owners to make clear, community-minded decisions that withstand technical, regulatory, and public scrutiny, supporting both resilience and transparency.