Nearly 90 percent of dams in Boone County unregulated
The Missouri Department of Natural Resources monitors just 17 of Boone County’s 127 dams, leaving the safety of the other 110 structures up to either local governments or private land owners.
The data come from DNR’s dam inventory and Boone County’s hazard mitigation plan. The report says that 34 of the 110 unregulated dams are considered a high risk – a designation the state gives to dams that, if they broke, could damage one or more homes and have a “probable loss of human life.”
DNR only inspects dams that are greater than 35 feet high, as required by state law. It inspects “high-risk” dams every two to three years, and inspects dams considered severe or low risks every five years.
The data, however, are based on information the state gathered in the 1970s and 1980s.
“Unfortunately, it is dated,” Boone County hazard mitigation specialist Jordan Wright said. “And that is a problem with aging infrastructure nationwide, and it’s a nationwide problem, not just a local problem.”
Wright said the best the county can do to ensure the safety of the unregulated dams is to try and work with the dam owners. The county sends letters to the owners it knows of, encouraging them to fill out an emergency action plan should the dam fail.
“We let them know the risk with a possible failure and the consequences of not doing upkeep or not being prepared for an emergency,” Wright said.
Few dams have burst in recent history. The county estimates that there is a 7.7 percent chance that a dam fails in Columbia or the county – the two locations where dams recently failed.
Cleanup after a dam failure can be costly. A destroyed dam drained the 17-acre Moon Valley Lake in east Columbia in 2008, costing the city $400,000 to remove the sediment that ran into the Hominy Branch Creek. The Federal Emergency Management Agency reimbursed the county at least $440,000 for a dam leak at Finger Lakes State Park.
Wright said that the Boone County Office of Emergency Management would serve as a coordinating agency for first responders should a dam break and cause significant damage.
The reliability of the state’s inventory is “a major looming issue” due to its age, according to Boone County’s 2015 hazard mitigation report. The county and state lack knowledge about the current condition and ownership of many of the dams because of the inventory’s age, the report said.
The county even added a dam near Hartsburg to its list of high-risk dams after someone brought its existence to the attention of the hazard planning committee. The McNew Lake dam sits uphill of the village, but village officials assured the county that the dam is a minimal risk for failure, according to the report.
