The revamped mouth of Bear Creek survived its first big test last week when it withstood the highest flows seen in the upper Rogue River in two years without unraveling.

The revamped mouth of Bear Creek survived its first big test last week when it withstood the highest flows seen in the upper Rogue River in two years without unraveling.

The $507,000 restoration project, which followed last fall's removal of Gold Ray Dam, held its own despite surging flows in both Bear Creek and the Rogue, with strategically placed boulders, root-wads and logs helping absorb the torrent's energy and curb erosion.

"It's awesome," said John Vial, Jackson County's roads and parks manager, who is overseeing the effort. "The structures are doing exactly what they're supposed to. We knew that was going to be a good test."

The soft banks of lower Bear Creek and the Rogue near the creek mouth contained some of the least-stable features of the new-look Rogue after the dam came out about a half-mile downstream.

Bear Creek's lower 1,000 feet were all underwater when the dam was in place, because the surface of the former Gold Ray Reservoir was higher than the creek mouth. That changed in August, when the 106-year-old dam was removed and the slack water drained, leaving an area ripe for erosion.

Armed with a NOAA Fisheries grant, contractors designed and built a reconstituted creek mouth meant to use natural materials to strengthen the bed and banks there.

The lower creek stretch was rechanneled and deepened, with decades of sandy material excavated and placed along the Rogue bank just downstream of the mouth.

Boulders, rocks and logs were structured to absorb the rushing water's energy during freshets, robbing it of its capacity to erode the banks and power its way along unwanted paths toward nearby gravel pits.

The first real test came Sunday, when last week's warm rain on mid-elevation snow swelled the Rogue and Bear Creek to levels not seen since 2009.

The Rogue peaked at flows of about 18,000 cubic feet per second near Bear Creek's mouth, while the creek itself churned at about 2,000 cfs — or 12 times the flow recorded Friday afternoon in downtown Medford, records show.

Both were considered two-year events, or the type of storm expected every other year, said Scott Wright, whose Corvallis-based River Design Group constructed the new-look creek mouth.

The high flows washed away much of the fine sediment laid against the Rogue bank downstream of the creek, "but we knew that was going to be washed away anyway," Wright said.

The structures, however, remain. The flows scoured a hole in front of Bear Creek, but the banks remained intact, even though willows and other flora planted there have yet to sprout their dirt-holding roots.

"The first winter is the hardest because it's so bare," Wright said. "It's relying just on the rocks and timbers. When some vegetation gets established, it'll only get better."

Reach reporter Mark Freeman at 541-776-4470, or e-mail at mfreeman@mailtribune.com.