The full report has not been released.
But dam owner Great River Hydro and officials at the Federal Energy Regulatory Commission are classifying the problem as minor.
“The incident involved a relatively small bulkhead, with the only impact a slight loss of water, and there was no danger to the public,” said Craig Cano, a commission spokesman. “A new bulkhead is being constructed, and we consider this work routine maintenance.”
Great River Hydro LLC, a subsidiary of Boston-based ArcLight Capital Partners, in April completed a $1.07 billion acquisition of 13 hydroelectric stations formerly owned by TransCanada.
The stations are on the Connecticut and Deerfield rivers and include the Vernon dam, which is more than a century old and stretches 956 feet across the Connecticut.
Great River is seeking to renew the Vernon station’s federal license.
Separate from that process, Great River in early June notified the federal commission that a wooden bulkhead had failed in Vernon.
FERC has released a short letter written by a Great River administrator. But the incident report is not available to the public because it has been labeled “critical energy infrastructure information.”
Federal law defines that as “specific engineering, vulnerability or detailed design information” that “could be useful to a person in planning an attack on critical infrastructure.” Such information is exempt from the Freedom of Information Act.
Great River’s John Ragonese, the company’s FERC license manager, said hydro station owners generally are required to report any structural repairs to the federal agency. It’s not an indication of a serious issue, he said.
“This is simply a case where we identified that a wooden cover had essentially broken,” Ragonese said.
He added that the issue is “in no way endangering the dam. … It’s just something that needs to be fixed.”