Portland, Ore. - Blue River Dam is a heavy collection of rock, 270 feet high and more than 1,200 feet long. It, along with Cougar Dam, another massive rock-fill structure, work in coordination to provide flood risk management along the McKenzie River, a tributary of the Willamette River.

This year, Blue River Dam turns 50-years-old, and marks the 50th commemoration of the completion of the entire system of U.S. Army Corps of Engineers' 13 dams in Oregon's Willamette Valley, which has been systematically protecting people, infrastructure and a way-of-life since 1969.

Flood control was the main driver behind the multiple purpose development of the Willamette River Basin after World War II. The Flood Control Act of 1938 outlined the basic development, and prompted the construction of the Willamette Valley Project's first two dams: Fern Ridge and Cottage Grove. Additional Flood Control acts resulted in the construction of a total of 13 dams and reservoirs that make up the Willamette Valley Project.

The great flood in December 1964 put these projects to the test. The end result was flood prevention benefits amounting to $514 million (about $4.2 billion today), over twice the cost of the projects completed at the time.

"It's interesting to think about how settlement patterns have changed in the Valley," said Cameron Bishop, Willamette Valley Project environmental specialist. "We're occupying areas where we normally wouldn't because of the lessened risk from floods. It's a strange tension," he said.

Portland District owns and operates Blue River Dam and the 12 others within the Willamette system. The District estimates that the system reduces the impacts of flooding enough to save the state of Oregon, its taxpayers and the roughly 70% of the state's residents who live in the valley more than one billion dollars on an annual basis.

Even with the annual savings and an estimated savings of $26 billion dollars since 1994 from the reduction of floods and flood severity, the system has presented challenges. For one, many of the high-head dams block fish passage to Endangered Species Act-threatened species. Additionally, when the Corps built the structures, some lands were inundated with water, resulting in the government relocating homes and towns. These reservoirs also change water temperatures, which can have multiple impacts, some to fish and wildlife, others to water supply and quality.

"Our system has allowed Willamette Valley residents to live with less disruption from flooding because we can take the peaks off of flooding events," said Dustin Bengtson, Willamette Valley Project deputy operations project manager. "But people have to realize that there are trade-offs and our agency has to balance those competing needs."

As one can conclude by the amount of money saved throughout the system's history, even with the challenges it represents, the Willamette Valley Project has had an immense impact on communities downstream of the dams for the past 50 years.

Learn more about the Willamette Valley Project at: https://www.nwp.usace.army.mil/Locations/Willamette-Valley/