Al Longman learned that his home sits next door to a “high-hazard” dam only when the state delivered legal papers claiming he should be on the hook for maintaining it.
“I didn’t know it was a dam,” Longman said of the tree-covered earthen embankment that supports Lake Forrest Drive beside his driveway. “I didn’t honestly know there was a lake across the street.”
Three years later, the city of Sandy Springs has taken the lead on assessing and upgrading Lake Forrest Dam, and Longman said he has been ruled out as a co-owner. Along the way, he saw a map of the dam-failure flood zone that did not include his house, but showed about 20 homes downstream at risk—“a lot of houses [whose owners] would be totally unaware” of the dam, he said.
Finding out whether you live or work in the flood zone of one of Georgia’s 474 “high-hazard” dams is surprisingly difficult, acknowledges Tom Woosley, head of the state Safe Dams Program.
There are 11 such dams in the Brookhaven, Buckhead, Dunwoody and Sandy Springs areas. Two of them—Sandy Springs’ Lake Forrest and Tera Lake dams—are in a condition that concerns state inspectors. “High-hazard” is a classification that means if the dam fails, the flood likely would kill people. It does not represent a judgment about the condition of the dam.
How do those people at risk learn about the existence of the dams, which are often privately owned and hidden within housing developments?
“There’s not a straight answer on that,” Woosley said. “Most people have no idea” they are in a high-hazard dam’s flood zone, he said.
Woosley’s agency inspects dams regularly, but its files can be hard to access and difficult to use and they rarely include a flood map. Federal guidelines call for owners of high-hazard dams to notify people downstream and have an emergency response plan for imminent failures. But Georgia currently requires that only for new dams, not existing ones.
The lack of such records is largely due to funding and staffing of the Safe Dams Program, said Woosley. The budget increased last year, but the program still has only 11 inspectors for more than 4,200 total dams statewide. “If we required them all [to have emergency plans on file], there’s not enough engineers to get [the necessary work] done and probably not staff time to get it done,” said Woosley.
Standard flood insurance requirements are not a reliable guide, either, said Woosley. The volume of water pouring out of a broken dam can exceed the so-called 100-year flood zone that triggers federally required flood insurance.
“The dam failure flood zone is different from the 100-year flood zone,” Woosley said. “In general, a dam failure would be bigger…People may not live in a 100-year flood zone, but may still be living in a dam break [flood] zone.”
Dan King, who runs the New York State-based website FloodBroker.com specializing in flood insurance, agreed that insurance requirements would not necessarily alert a homeowner about a dam. “[Housing lenders] probably don’t care about that…If it’s less risky, then they don’t care,” King said.
The Safe Dams Program’s own high-hazard dam list is a spreadsheet that locates the dams only by map coordinates within counties. Inspection reports are available only in paper files that must be viewed by appointment at a downtown Atlanta office building. They typically lack information on the endangered properties that triggered the high-hazard classification.
“There’s not a complete picture” in state files about which properties would be flooded, Woosley said, even though Safe Dams has software that could model the disaster. That’s because it only takes one endangered occupied building to trigger the high-hazard classification, and due to staffing, Safe Dams usually stops its analysis there.
Finding that first building can be simple. “Some, you stand on the dam and you’re looking over the roof of a house,” Woosley said.
But Lake Northridge in Sandy Springs is an example of a dam’s potentially nasty surprise. Woosley said that Safe Dams determined that if the Lake Northridge dam failed, the “flood wave” would cross the Chattahoochee River and hit a house on the other side.
Georgia’s Safe Dams Program is working on a rule change to require plans for all high-hazard dams, Woosley said. But in the meantime, his best advice on figuring out whether you live in a dam flood zone is to look for blue dots on a map. “Certainly, if you’ve got a lake here in Georgia, then there’s a dam holding it in,” he said.
Editor’s note: This is one of a series of articles Reporter Newspapers is publishing about dams in our communities. Previous installments have looked at the location and condition of the 11 local high-hazard dams and the costs of maintaining high-hazard dams.