I have been following the issue of controlling floods in the Chehalis Basin. There is a lot of information out there and certainly two sides to the issue. I would like to respond specifically to Mill Creek Dam in Cosmopolis.

The current Mill Creek Dam replaced a 1930s era dam that catastrophically failed in November 2008. The new dam has been billed and funded as a flood control dam and yet it provides little to no flood control benefit. By their own records, the reservoir pond would fill in less than an hour during even a modest flood. A 100-year-flood would crest the dam in 22 minutes and continue downstream at full force. Given the likelihood of increasing flood events we have been told to expect several 100-year-floods in any given 100-year period. Indeed we have already seen this happening.

Not only does Mill Creek Dam not provide flood control, it is highly likely to provide warmer water into the lower creek, harming juvenile salmonids rearing there. Storing water in the pond during the summer will provide a large surface area for solar heating. Compounding this warming will be the water trapped in the pools below the dam that won’t be mixed with flow through water from the fish ladder when the pond is filled. There is plenty of evidence that warming water impairs salmon and trout production.

Mill Creek Park is a great community gathering space. The pond is a beautiful centerpiece in the summer when it is filled. However, spending Chehalis River Basin Flood Control Authority dollars on a project that clearly doesn’t offer meaningful flood control is a waste of taxpayer dollars and calls into question all projects funded by the authority. If this is the kind of work we can expect from the Chehalis Basin Partnership and Flood Authority, we need to question everything they say about the benefits of a dam on the upper Chehalis River or any other flood control projects.

Jon Harwood

Aberdeen