$691M Howard A. Hanson Dam Overhaul to Expand Water Storage, Aid Salmon

Why It Matters

By simultaneously boosting water storage and restoring salmon migration routes, the project strengthens flood protection for thousands of homes and supports a keystone species vital to the Pacific Northwest economy and culture.

Key Takeaways

• $691M contract awarded to Flatiron‑Dragados‑Aecon JV
• Fish passage facility adds vertical ports for juvenile salmon migration
• Expanded storage improves flood control and water supply for thousands
• Project supports Puget Sound salmon recovery and regional economic growth
• Integrated design‑build model speeds delivery and reduces project risk

Pulse Analysis

The Howard A. Hanson Dam, operating since 1961, has long served as the primary flood‑control barrier for the Green River Valley. As climate variability intensifies, the region’s demand for reliable water storage has grown, prompting the U.S. Army Corps of Engineers to invest heavily in expanding the dam’s capacity. The additional storage will smooth seasonal runoff, ensuring a steady supply for Tacoma’s drinking water and for agricultural users while preserving the dam’s ability to blunt peak flood events that threaten thousands of downstream properties.

Ecologically, the dam’s original design fragmented salmon migration routes, contributing to the steep decline of Pacific salmon runs that underpin both commercial fisheries and Indigenous cultural practices. The new fish‑passage facility employs a multi‑port collector, steep‑slope bypass channel, and deceleration tunnel to mimic natural river conditions, dramatically reducing stress and mortality for juvenile salmon. Restoring access to roughly half of the upstream habitat is expected to boost spawning success, reinforcing broader Puget Sound recovery efforts and delivering measurable benefits to the regional ecosystem.

From a business perspective, the project showcases a modern integrated design‑build approach that brings engineers, designers, and contractors together early, cutting schedule risk and fostering innovation. For Aecon and its partners, the contract represents a strategic foothold in North America’s aging dam infrastructure market, where similar upgrades are increasingly sought to meet climate‑resilient standards. The $691 million investment signals federal commitment to infrastructure that balances public safety, water security, and environmental stewardship, setting a precedent for future multi‑benefit projects across the United States.