A joint venture led by FlatironDragados, alongside Canada-based Aecon, has secured a $691 million contract to deliver a major water infrastructure upgrade in Washington state. The project, commissioned by the U.S. Army Corps of Engineers (USACE), will focus on enhancing water storage capacity and enabling fish passage at the Howard A. Hanson Dam.
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Located roughly 35 miles southeast of Seattle in Ravensdale, the project marks a significant step forward in improving regional water reliability, environmental restoration, and flood protection along the Green River watershed.
The project will utilize USACE’s integrated design and construction (IDaC) approach, which brings designers and contractors together early in the process to streamline execution and reduce risk. This collaborative model has already guided the project through its design phase and will continue into construction.
“In partnership with Aecon, we worked closely with USACE, Tacoma Public Utilities and other stakeholders throughout the collaborative design phase,” said FlatironDragados COO Richard Grabinski. “As we advance to construction, we will continue that approach through the IDaC delivery model that will enable ongoing coordination, proactive risk mitigation and safe, efficient project delivery for the Green River watershed.”
With the design phase now complete, the project is moving into construction, where teams will begin building infrastructure aimed at balancing ecological needs with water management priorities.
The scope of the project includes constructing a sophisticated fish passage system that will allow juvenile salmon to safely bypass the dam—an essential step in restoring access to upstream habitats. Key components will include a multiport collector, bypass channels, a deceleration tunnel, and an outfall basin.
Beyond environmental improvements, the project is expected to significantly expand water storage capacity, ensuring long-term supply for residential and economic growth in the region.
“This project significantly expands our water storage, ensuring a reliable supply for thousands of homes and supporting the future economic growth of the region, while also providing salmon access to nearly half of the Green River habitat above the dam,” said USACE Seattle District Commander Col. Kathryn Sanborn.
Construction is scheduled to begin in the second quarter of 2026, with the project playing a dual role in infrastructure modernization and environmental stewardship. By integrating flood risk reduction with ecosystem restoration, the initiative reflects a growing trend in U.S. infrastructure toward multi-benefit projects.
The Howard A. Hanson Dam has long been a critical asset for flood control in the region. However, evolving environmental standards and population growth have increased the need for upgrades that address both sustainability and resilience.
This contract also reinforces FlatironDragados’ and Aecon’s presence in large-scale water infrastructure projects across North America. Their collaboration on this project highlights the increasing reliance on joint ventures to tackle technically complex and capital-intensive developments.
As climate variability continues to impact water systems across the western United States, projects like this one are expected to play a key role in securing water resources while preserving natural ecosystems for future generations.
Originally reported by Zachary Phillips, Editor in Construction Dive.
