09/09/09 UPDATE: Check out this video of potential effects of the problems with the Howard Hanson Dam, made using Depiction!

On Tuesday, February 10, 2009 I went to a public meeting in Auburn, Washington concerning the increased risk of flooding in the city. The Howard Hanson Dam, a flood control dam 30 miles upstream on the Green River, was weakened by the flood event in January.  The United States Army Corps of Engineers (USACOE) which maintains the dam, protected the communities downstream by not releasing the excess drainage from the Green River Basin. This created a record-level level pool behind the dam.

When the USACOE could finally lower the level of the reservoir, they found two “depressions” in the dam. They’re a different geologic phenomenon than sinkholes, but I think the concept of sinkholes helps me envision what happened.  The integrity of the dam is not compromised, but the capacity of the dam is reduced. Therefore, millions of gallons of excess water will go downstream into the Green River floodplain during future flood events.

What might this mean for people downstream? Click here to read more.