The US Army Corps of Engineers lawfully updated its plan to manage the Allatoona Lake dam and reservoir project in Georgia, a federal judge ruled.

The Corps has significant discretion in balancing competing project purposes at its various reservoirs, Judge Emmet G. Sullivan of the US District Court for the District of Columbia said.

In 2015, the agency amended its “Master Manual,” which is used to govern the operation and management of water resources, to account for changes in hydrology and the increased demand for recreation and environmental conservation at the Allatoona Lake dam near Atlanta. It altered the hydropower …