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Past Tolt floodplain project untested, but working well for fish

This King County video still shows baby salmon swimming in the Tolt River, where a 2009 river project improved habitat. - Courtesy photo
This King County video still shows baby salmon swimming in the Tolt River, where a 2009 river project improved habitat.
— image credit: Courtesy photo

Since the fall of 2009 when King County completed a levee removal project in Tolt Mac-Donald Park, Carnation, the Tolt River hasn’t seen significant flooding. It’s a good thing for the surrounding area, but not a true test of the project, which is similar to the Upper Carlson Floodplain Restoration project underway near Fall City.

“We’re trying to reconnect floodplains, and restore the natural processes of the river,” said Snoqualmie River Basin Supervisor Clint Loper, who worked on the Tolt Floodplain Restoration project, but only a flood can push the river out of its channel. The Tolt’s record high flow, 13,8000 cubic feet per second, occurred in January 2009, when the project was less than half done; since then, the highest flow was 7,100 cfs, still a flood, but not significant enough to shift the river, even temporarily.

In terms of the project goals, though, Loper considers it a success. The half-mile levee was removed and set back 800 feet to improve salmon habitat, maintain the level of flood protection and to enhance the recreational use of that stretch of the river. Logjams were installed in the floodplain to slow the rush of floodwaters, invasive plants were replaced with natives, and a new paved trail was built along the new levee in the $6 million project.

“In all the events so far, there have been no problems with the features that were built,” he said.

Plus, with the levee gone and the river able to flow and erode the bank, “it can begin to create more much complex and diverse edge habitat,” said Loper. “The length of that edge is much longer than it used to be,” he said, and the young fish access to slow water is better, too.

The fish in a recent video, online at http://vimeo.com/93543245, seem content.

Flood protection is unchanged or better, since the setback levee is the same height as the levee that was removed, and people are enjoying the river in new ways, since the project was completed.

“I’ve heard very good reaction from the local community, in terms of having this basically new trail system with these beautiful new views into areas that used to be in accessible,” said Loper.

The Tolt Floodplain Restoration project also received a Puget Sound Champions award from the Puget Sound Partnership Jan. 7, 2013, for the salmon habitat restoration accomplished.

 

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