Archive for June 20th, 2008

June 20, 2008

Flood Issues are Drowning Us

by Steve Dana

Now that the county has denied the application from Snohomish to expand their UGA to the north, they have pretty much closed down that city.  In previous actions the county council decided that development south of the city across the Snohomish river would be discouraged.  The flood plain regulations currently in place prohibit new commercial activity in that area along with denying existing businesses the opportunity to improve their situation.

Snohomish worked with Snohomish County to develop the Urban Growth Boundary in the beginning because both governments recognized that in spite of the fact that there is periodic flooding, the area was still urban and they would expect additional development.  Including the sawmill, the airport and the surrounding lands in the UGA makes good sense.  Those are important businesses in our economy and they have long history in our community.  We need to recognize the fact that in spite of periodic flooding, both have continued to invest in rebuilding whenever there was an event.

The politics of flood plain regulations has swung back and forth so many times I have doubts about the science.  Common sense tells me that the railroad tracks create a barrier to flood waters on both the north and the east sides of the airport.  In my mind that says that in the event that the water came over the dike anywhere in the vicinity of the airport, the airport would not impede the flow since the water wants to flow west.  There would be some pooling of standing water, but not floodway flow.

We did have a catastrophic dike failure in 1990 that allowed floodwater to ravage the area around Batt Slough.  That event did fill the valley with water.  But after the tub was full, we just had a big lake.  There was infrastructure damage along Springhetti Road and the south margin of Airport Road when the dike failed and the flow swept through the area.  There is no doubt that when a dike fails, there is significant damage. 

If however, there is predictable overtopping of a dike, there is more controlled flooding that is aimed to areas where there are less impacts to improvements.  The diking districts plan for overtopping by designating places for controlled flooding.  Certainly it does not prevent damage, it just tries to control it.

The dike along our river has been built to protect from most flood events.  It does its job pretty well.  Periodically, a significant event reminds us that it is not perfect.  The question we have to ask ourselves is “Because our dike is not perfect, do we abandon the valley?”  Are we suggesting that all places that have periodic flooding should be abandoned for human use? 

In the Mississippi River drainage area, we are seeing catastrophic flooding this month.  Dikes protect developed land along all those rivers.  If our logic is to remove the dikes and let the water flow where it may in all the places where there is periodic flooding, we might run into a little resistance in the heartland.  The federal government is pouring billions into the protection of the lower Mississippi valley.  They must not agree that we should abandon low areas along rivers that flood now and then.

Officials from both the city and the county have sent mixed messages to property owners on the south side of the river.  The map shows they are designated for URBAN GROWTH by being included inside the boundary.  The lengthy debates since 1994 have not answered any of the questions.  We are more confused than ever.  

For the city’s part, they are no better.  On the one hand they talk about the things the south siders can’t do, then propose some of those same land uses on the north side of the river.  The city built up the protective berm around the sewage treatment plant as they should have.  That berm elevation is a couple feet above the 100 year flood level.  That act alone prevented the river from flowing freely in places where it had done so for all of history.  That was “Flood Way” in that during a flood event, the water flowed with river velocity right through that site prior to the improvements.

The city built their maintenance facility on the river bank many years ago.  Some years the river flooded and the water came up into the buildings and did damage to the equipment and buildings there.  The city did not abandon the site because of periodic flooding, it did what anyone would do.  It filled the site to raise the elevation above flood levels.  It makes perfect sense.  If it floods, fill.

When the Snohomish Iron Works wanted to build a dike to prevent flooding in their shop, that was not an option available for them.  When the Seattle Snohomish Mill wanted to build a dike to keep flood waters out of the mill yard, they couldn’t either.

It is clear that the politics of flood plain regulation need more work.

Now comes the “Rails to Trails” organization suggesting that the rail line from Snohomish to Bellevue could be a component in the east side transportation corridor.  Imagine the troubles that project will face if the north terminus and staging for that deal lands at Harvey Field.  What compromises will that force?

These issues are complex.  I have not done them justice in this space.  The debate will rage until we clarify what our priorities are in this area.

The critical area regulations will be up for review before too long.

There is no doubt that we will have thoughts along the way.