Howard Hanson Dam Danger

After a huge rainstorm last January the Howard Hanson Reservoir on the upper Green River received more water than engineers desired, causing the Corp of Engineers to classify the dam as unsafe. The worry is not that the dam itself may fail, but instead it is because of the abutment on the right side of the dam has begun seeping water (again) and failure of the abutment could be catastrophic.

A similar problem happened with the Teton Dam Disaster, only it resulted in severe flooding and loss of life from the abutment failure.

In the meantime, less water is being stored behind the dam while repairs are being made. If there is another heavy rainstorm however, before the reservoir's repairs are completed, the Corp of Engineers advised they may have to release a large amount of water downstream. This water might flow over the downstream levees, flooding schools, businesses, and homes in Kent, Renton, Auburn and Tukwila. One of the worst case scenarios is possible flooding of the water sewage treatment plant in Kent downstream.

Contractors are working very hard to fix the leak while the Corps of Engineers designs a more permanent fix — like a concrete wall to seal the abutment once and for all, to the cost of many millions of dollars.


There is a high chance of a major flood this fall or winter. Local cities and both King and Pierce counties are hurrying to move critical infrastructure out of the flood plain and are currently doing lots of sandbagging to beef up the levees, and are notifying businesses and the thousands of residents downstream to prepare for the worst.

Keith Ervin, a Seattle Times Staff Reporter, wrote an article entitled, Rush to finish barrier at Howard Hanson Dam before heavy rains on October 5, 2009. He reports that, "Seepage through a dam or abutment isn't necessarily a problem. But if dirt and rock begin to wash away — as may have happened in January — the result could be catastrophic. Failure of the dam would send a wall of water careening toward homes, schools, warehouses and factories. Six cities would flood, from Pacific to Renton, with peak depths of some 20 feet in downtown Auburn."

So, if you live in the lower areas of these cities, seriously consider making preparations for that 'just in case' scenario of flooding evacuation. At a minimum, 1. Go out and purchase home and or business flood insurance, (if it is still available), 2. Purchase a NOAA weather alert radio, and keep it turned on, and 3. Sign up to be on the flood alert phone notification list.

Remember, time will always be short if a failure does occur. Preparation is the only viable answer to protecting life and property.