SHADY COVE — Nicholas Broussard knows that living seven miles downstream of Lost Creek dam means that there is an ever-so-slight chance the dam could fail in an earthquake, inundating his home and most of Shady Cove.
Sure, the Rogue River would rise nearly 100 feet in three hours in Shady Cove, but at 10,000 to 1 that it could happen in any given year, the retired physician isn't ready to head for the hills just yet.
"I don't think it's a possibility, but if it did I don't know what the hell I could do about it," Broussard says. "I spent 30 years in the military. I know how to be prepared.
"But anytime the ground shakes, that's scary," he says.
Broussard says catastrophic dam failure doesn't keep him up at night, but it did get him to attend a Monday meeting with the U.S. Army Corps of Engineers to learn just what the upper Rogue Valley would look like in a worst-case scenario of dam failure.
About 100 lowlanders pre-registered for Monday sessions at the Shady Cove library to see the Corps' new not-for-publication "inundation maps" that outline when and where water would work its way down the Rogue under two different dam-breaching scenarios.
Data, some of which is controlled by the Department of Homeland Security, helped create what Corps dam-safety manager Matt Craig says details the consequences of dam failure, but not the risk of events that could trigger a failure.
The intent is to show riverside residents whether their land and lives would be at risk of inundation should the nearly 40-year-old Lost Creek dam fail, give emergency-management responders information on who is at risk and prime the pump to get residents prepared.
Should the Corps sense a dam-failure coming, officials would telephone 911 and set in motion a series of alerts to warn people to get to high ground.
"It's your responsibility to make sure your family, your pets and your property are protected," says Jackson County Emergency Manager Sara Rubrecht, who intends to use the Corps data to create a system to notify everyone in the inundation zone should that call from the Corps occur.
The updated maps include the two dam-failure scenarios — a so-called "sunny day" failure with a full spring pool and normal river flows, and a worst-case scenario of failure during a massive storm when downstream water levels are already high.
Draft maps for a sunny-day failure calculate that Shady Cove residents would see a rise in the water in two hours and that level would peak at 92 feet above normal flows an hour later.
In the worst-case flood scenario, it would take about an hour for flows to show up at Shady Cove and they would peak at 97 feet above normal river level two hours later.
Similarly, the worst-case-scenario inundation would actually push water into portions of Central Point, according to the maps. Four hours after failure, water would start to reach Central Point and peak three hours later at almost 49 feet higher, stretching past Scenic Avenue west of town and into the Jackson County Expo to the east, but downtown would be spared, according to the Corps maps.
That same maximum inundation would see water showing up in Gold Hill five hours after the dam failure and peaking three hours later at 28 feet above normal river levels, according to the Corps maps. Water would reach into about half of the downtown and residences immediately to the north, the maps show.
Like most in attendance, Shady Cove residents Paul and Joyce Chapman worry how quickly they would be notified should a large earthquake shake the dam into pieces.
"I need to know how long I have to evacuate, to get my family out of the area," Paul Chapman says. "We don't want to move, but we do want to be able to get away."
Jim Buck, the Corps' Rogue Basin operations manager, says the water would not come in a wall, but build up and peak in towns like Shady Cove before ebbing. But if you feel the ground shake, "head to high ground," Buck told the crowd.
Sharon Erwin, who lives in the Cole Rivers Hatchery residences immediately downstream of the dam, saw on the maps just what she expected.
"We live there," Erwin says. "We've got two minutes. We're screwed."
A similar series of small-group meetings is planned from 3 to 8:30 p.m. tonight at the Anne Basker Memorial Auditorium in Grants Pass. To reserve a spot in one of those sessions, visit http://ow.ly/Svbdj.