Towns Below Dam Haven’t Planned For Flooding Evacuation Plans Needed In Case Grand Coulee Fails, Federal Officials Say

None of the more than two dozen communities and counties downstream from Grand Coulee Dam, including Richland, Kennewick and Pasco, have emergency evacuation plans in case it breaks, federal officials say.

Grand Coulee and the other 13 Bureau of Reclamation Dams in Washington state are considered safe, but Bureau officials are concerned towns below the dams may not be adequately prepared if one failed.

Only 3 percent of the communities in the Northwest have plans that deal specifically with the collapse of a dam, compared with 10 percent nationwide, the Bureau found in a study.

Almost half have generic emergency plans, but the Bureau believes that may not be good enough. “What we learned was very unsettling,” said Reclamation Commissioner Dan Beard. “We want to make sure that communities establish these plans because they’re extremely important.”

Beard said the Bureau will make available $1.4 million to help the communities to develop such plans. The money wouldn’t come in the form of grants, but in the time and expertise of Bureau staff.

The plans would include what areas would be inundated, which evacuation procedures should be followed and who should be called.

Beard said the dams were in “excellent repair and are eminently safe. However, the volume of water in many reservoirs demands that localities take prudent steps to prepare for any eventuality.”

Of the Bureau of Reclamation dams in Washington state, Grand Coulee is by far the largest. According to Bureau estimates, the flood wave from a collapse of Grand Coulee would back-up the Okanogan River as far as Omak in three and a half hours, reach Wenatchee on the Columbia in 10 hours and the Tri-Cities in about 24 hours.

While that may seem like plenty of time, the Bureau said if Grand Coulee were to collapse, all downstream dams would immediately start spilling water to make a “hole” in their reservoirs in an effort to lessen the chances of another dam failing.

Most of the dams, with their spillways open, can release 1 million cubic feet of water a second, which, according to the Bureau, would produce a “very severe flood in itself.”