Mayor Nancy Backus got the go-ahead from the City Council Monday night to negotiate the purchase of three parcels of land crucial to the Mill Creek Wetland 5K restoration project west of State Route 167 and south of 15th Street Northwest.

Auburn and the Seattle District of the Army Corps of Engineers have agreed to work together to rehabilitate that portion of the creek that lies mostly inside the second phase of the Auburn Environmental Park. The project’s purpose is to substantially reduce flood hazards and create better conditions for fish and wildlife by providing 17.5 acre-feet of additional flood storage within the floodplain.

The smallest parcel the City looks to buy, for an access easement, is .05 acres on the north end of the project, owned by Orchard Industrial.

“The guy keeps the property, while we and the U.S. Army Corps of Engineers get an easement to fix the stream,” City Councilman John Holman said Tuesday.

The second calls for the outright acquisition of three parcels owned by Willis and Carolyn Calhoun, totaling 7.13 acres. The third is 1.5 acres owned by the Washington State Department of Transportation, which it has declared surplus. Auburn already owns the rest of the land it needs there.

The origins of the creek’s problems date to an undertaking more than 100 years ago, when valley farmers straightened the original creek bed, turning into a ditch. As a straight ditch, it drains but then backs up along a course that continues in a pipe underneath 15th Street Northwest to the Green River. The upshot is that formerly rich salmon habitat that once held floodwater from the swollen Green River backs up, and the water has nowhere to go except into that ditch.

The construction of State Route 167 in 1970 added to the drainage area’s woes, making it even more prone to floods, which endanger developments like Emerald Downs and traffic corridors such as SR 167 and West Valley Highway.

City officials expect the restoration project to enhance the ecosystem functions of the creek by creating more complex stream habitat, establishing native vegetation in the riparian areas and improving fish passage.

“When the Green floods, the water will also have a place to back up so it doesn’t flow over the West Valley Highway. This’ll give us more retention space,” Holman said. “The beauty of this deal is that our partner, the Army Corps of Engineers, will pay us 75 to 80 percent of the cost of the project, including the land acquisition, plus they will pay us 80 percent of the cost of the property we already own there. So it ends up costing the City zip, but not until the deal’s done. We’ll have to come up with $5 million up front, but when it’s all done in a couple of years, we get the money back.

“Everybody wins, including the little salmon and the five families of beaver that have made their dams on the thing,” Holman added.