Know the risks are real from flooding in the Green River Valley

KING County's pre-emptive declaration of a flooding emergency in the Green River Valley properly anticipates the vulnerability of 35,000 residents downstream from Howard Hanson Dam.

Individual citizens, property owners and businesses, as well as all levels of government, must plan for and expect the worst. Be thinking about evacuation routes and buy flood insurance. Sound alarming? Good.

Information is power. Officials need to be aggressively working to get the multilingual word out about the flooding hazards this rainy season. People in Auburn, Renton, Kent, Tukwila and unincorporated areas need to pay attention.

The U.S. Army Corps of Engineers bluntly assesses the flood risk to lives and property downstream from the federally owned and operated dam at roughly 1-in-3. The dam itself is sound, according to the Corps. Record rains in January 2009 damaged the structural integrity of the pile of rocks and debris — not bedrock — that form the dam's right abutment.

Work to seal leaks and improve drainage is targeted to be finished before Nov. 1. Weather experts warned officials that two of the heaviest weeks of rain before spring are the last two weeks of November.

The Corps' strategy is to release water earlier to avoid a larger pool behind the dam. Heavy rains mean releasing more water, and those increased flows may exceed levee capacities downstream. Here is the spooky part. Weather forecasts will factor into those releases, and the spigots could be opened and the torrents arrive when it is not raining.

King County government, with nimble work by County Executive Kurt Triplett, is borrowing money to build protection and start relocating government functions, from elections to criminal justice. The plan is for interest-only loans until federal money arrives, as it should.

This is a problem inflicted on the Green River Valley by a federal facility. Washington's congressional delegation is uniting in a bipartisan effort to secure financial aid. Current rules are perversely written to be activated after the devastation. Infinitely cheaper and fundamentally more humane preparatory work is not covered.

County estimates of potential financial damage run to $4 billion and hundreds of buildings destroyed or damaged. Contingency planning looks to 5,000 evacuees.

The Corps' mission is get the Green River Valley through this event, and then find a fix that does not leave King County wringing its hands every time it rains. Local government is duty bound to ensure the word gets out. There is no excuse for the shame of Katrina to be repeated here.