Sunday, September 20, 2009


So this is what happens when you put things aside - the mainstream media gets hold of a story before you get around to talking about it.

I've been meaning to post about the Hanson Dam situation. Sacnoth has been doing a good job keeping up with it, but then, living in the Green River Valley, he has a vested interest in the entire situation.

Here's the story. The Green River flows out of the Cascade, north through the valley to the sound. Once it was joined by the White River near Auburn, but after a flood, that river changed its banks and now flows towards Tacoma. And it was once joined by the Black River, which disappeared when the level of Lake Washington dropped with the Montlake Cut. So it does not have the force it once did.

However, it does have a lot of force, and I've seen pictures of the early days when the local farms and racetrack was inundated by floodwater. In the early 60s, the Howard Hanson dam was installed upstream of the valley to regulate the floodwaters, and in addition, the river itself was dredged and banked with a series of levies, changing its flow from a ever-changing meander to its present course.

And in the wake of that control development spread through the valley floor, including the huge mall (still called by the locals Southcenter, though it is really now officially Westfield) and a lot of light industrial and residential growth.

Which is all well and good as long as the dam does its job. However, after the flooding of last year, the dam began to leak. Waters usually held back have found other paths, and the integrity of the dam is threatened. As a result, the dam will pass along water that it would normally hold back, or else risk failing. And that excess water passes downstream to the developed valley.

The current plan is to inject a grout curtain to stem the leakage, but this is at best a patch, and the results of the patch won't be known until the rains come again. So everyone downstream is getting a little nervous.

And they are looking towards the levees. There have been a couple failures in the past few years creating localized flooding, but the idea that there will be a systematic flood is making all the valley residents very concerned. In the wake of Katrina everyone started looking at their infrastructure, and a lot of levees came up, pardon the pun, short. Here's an article from USA Today that noted levees that were in such bad shape that, if they failed, the Army Corps of Engineers would provide funding to rehabilitate them. A lot of them listed in Renton are for the Cedar River (which is another valley, and I suppose a discussion for another time) but there are candidates on the Green as well. And mind you, these are just the ones that are so bad that the Army Corps doesn't want to deal with them. Not included are those that will be overtopped during a major flood.

All this puts local politicians in a bind - spend the money for levee improvements and get castigated if the floods don't come, or holding tight and being villains if Kent and Renton go underwater. I am in favor of the improvements (and the eventual replacement of the Hanson dam - no one seems to be talking about it, but its not like its going to get better over time). In the meantime, those on the valley floor should be thinking about flood insurance and go-bags, at least until we know the patch is holding and that the levees are up to snuff.

The local media has picked up on all this, and noted that the new Kent courthouse is ready to move at a nonce and the King County Elections Offices have already relocated. However, there is this large MALL right where the Black River used to flow into the Green which has just completed major renovations (and is not going anywhere), along with the new US Mint building and, oh, the Olympic Pipeline Hub nearby as well. Not to mention companies that range from Wizards of the Coast to biotech startups throughout the valley floor. So yes, the dam is the first line of defense, and the levees are the second, but should all watery hell break loose, this could be a major disaster.

But for the moment - flood insurance and go-bags.

More later,