Groups urged to come together, carefully mitigate river system | Hildreth
February 24, 2010 · Updated 4:39 PM
While I agree on the need to repair and, in some cases, replace levees along the Green River, I want to expand on the issue to discuss proper mitigation work that is needed on many rivers in King County.
The White River, which flows from the Mud Mountain Dam down through Auburn, Pacific and Sumner, has issues that are just as critical. But unlike the Green River to its north, it is not the lack of maintenance on the levees that is leading to the problems, it is a lack of measures to control or mitigate for the large amounts of debris that wash down from upstream every year.
Whether it’s a glacial melt on Mount Rainier or the impacts of development and storm water upstream, left unchecked we will see more frequent flooding as we saw a year ago in Pacific. As this debris continues to settle and build up, we can expect to see flooding of not only homes but of commercial and industrial lands in Sumner. This too could result in billion dollar impacts on our regional and state economies.
On the night of Jan. 8, 2009, more than 100 homes and businesses outside the 100- and 500-year flood plains were inundated with water because of a large of amount of debris dramatically and rapidly reducing capacity in the river. Less than three months prior, studies showed the capacity of the White River in Pacific was over 10,000 cubic feet per second (cfs). A USGS study last summer showed this had been reduced to 5,100 cfs, basically cutting the capacity of the river in half. Additionally, logs and other debris had built up in certain locations that could further choke off this river in the future.
These logs are not fish habitat, but remain out of the water until the next flood comes. There are, however, ways to mitigate for these problems.
King County currently has plans to create levee setbacks on both sides of the river that should restore some capacity. I wish to thank them for their hard work on these projects and pledge the cities full cooperation in making them happen. But, by themselves, these projects soon will lose effectiveness as gravel and other debris continue to build up. As one of these setbacks will create some exceptional fish habitat, I personally would find it a shame if it were only effective for a few years.
Now, no one wants to return to the days of wholesale dredging of the rivers, not caring what impact you are having on fish or other wildlife. In fact, what I propose could not only restore and maintain capacity without dredging, it also could further expand habitat and work with Mother Nature to enhance one of the most diverse areas in the county.
My proposal of engineered and select removal of debris on gravel bars and outside the normal course of the river would work in step with other projects to ensure they remain viable over the long term. This could be done at select locations up and down the White and other rivers and help control the rapid sedimentation that has resulted in this problem.
I call on all stakeholders for our river systems to start working together – from the Army Corps of Engineers, national and state fisheries and EPAs to the Tribal nations and environmental groups who wish for a healthy river system. We should not be standing in opposition to each other in protecting these valuable resources.
We need to work together, respecting each other’s concerns but keeping the focus on making progress. If together we were to work on better river management as a concept by itself, we would not then be playing catchup to fix crumbling levees or to mitigate for buildup in our rivers.
Pacific Mayor Richard Hildreth can be reached at firstname.lastname@example.org.