Updated Maps Show Potential Aftermath of Lane County Dam Failure
On March 19, 2014, the U.S. Army Corps of Engineers let about 300 residents of Eugene and surrounding cities view updated maps showing the possible aftermath of a catastrophic failure of any one of Lane County’s nine major dams—Blue River, Cottage Grove, Cougar, Dexter, Fall Creek, Fern Ridge, Hills Creek, and Lookout Point. Additional viewings/meetings on the matter are scheduled for April in Springfield and Cottage Grove; Westfir residents took part in a similar meeting on March 18.
Officials from the Corps stress that a dam failure in highly unlikely. The maps are intended to be used as tools for local emergency managers to assist them in drafting response plans should such a remote possibility come to pass. In one possible scenario, the failure of Hills Creek Dam finds parts of Eugene’s University of Oregon campus under seventeen feet of water roughly fourteen hours after the dam bursts.
The maps specify areas that would be flooded, water levels at the start and the peak of flooding, and the time between the start of flooding and peak levels after a dam failed. Hospitals, police and fire stations, and schools are also identified.
Flood plains are mapped in two variations: “sunny day failures,” where both reservoir levels and in and out flow are normal, and worst-case scenarios where reservoir and flow levels are much higher than usual.
Map viewing sessions were not open to members of the public—the Corps of Engineers arranged viewings for residents who had asked in advance to see the maps. Public interest in the maps grew considerably after the Eugene Register-Guard reported that the Corps had updated them, the first update to the maps in over 30 years.
While future public viewing sessions are being considered, Corps officials say the maps will not be released publicly because of federal security requirements, as well as the complexity and one-sidedness of the maps.
Technological advancements have made it possible for the Corps to develop more detailed and accurate maps, according to the Portland district’s dam safety program manager, Matthew Craig. The Portland district was one of the first in the United States to receive the newly-updated maps.
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