prensa-1265--md
News

FlatironDragados to construct Howard A. Hanson Dam Additional Water Storage

Mar 11, 2026·1 min read
FULL NEWS

FlatironDragados and joint venture partner Aecon have finalized a $691 million contract with the U.S. Army Corps of Engineers, Seattle District, to deliver the Howard A. Hanson Dam Additional Water Storage Fish Passage Facility in Ravensdale, Washington.

Employing the Integrated Design and Construction method developed by USACE, this collaborative approach brings together the designer of record and contractors from the early design phase through construction. The model improves coordination, helps mitigate risk and enhances cost and schedule certainty — supporting early alignment among project stakeholders and more informed decision-making throughout the project.

Following successful completion of the collaborative design phase, the project now is advancing into construction to deliver enhanced fish passage, ecosystem restoration, water supply reliability and flood risk reduction.

Located about 35 miles southeast of downtown Seattle, the project will improve passage for juvenile out-migrating salmon in the Green River. The facility will allow salmon to bypass the existing dam, supporting conservation of key species while maintaining flood risk management for the region. The facility will include a fixed multiport collector, steep slope bypass, deceleration tunnel and outfall stilling basin structures. This project enhances environmental resiliency in the Pacific Northwest.

Construction is expected to begin in the second quarter of 2026.

You may like...