Baker Rock also produces asphalt from a plant near Beaverton and a second one in Dayton.
Oregon Mainline is an asphalt paving contractor with reach into California, Idaho and Washington. It operates two portable asphalt plants and three paving crews.
Knife River CEO David C. Barney says: "Oregon overall and the Portland area specifically have been strategic growth markets for us for many years, generating strong earnings and overall returns. As the Portland metro area continues to grow, so has the demand for construction aggregates, which have become more scarce in recent years through depleting resources and increased land development. Acquiring this excellent aggregate resource helps replenish our reserves near the heart of the growth and positions us for continued success in an area we know very well.
"Additionally, Oregon Mainline provides greater reach for our paving operations in the Northwest," Barney said. "We are excited about bringing 230 employees from Baker Rock and Oregon Mainline to our team and look forward to the value they add in this important market."
MDU CEO David L. Goodin says: "With Knife River's history of success in Portland and the growth anticipated there, we believe this is the right deal at the right time. Aggregates close to this market are only going to become harder to find, so acting now to secure this long-term resource will benefit Knife River and MDU Resources today and for many years to come."