Duke Energy said the gauge by which it tracks lake levels apparently went on the blink about three weeks ago. It was recalibrated and will be replaced. Residents of Gar Creek Cove, on the lake's Mecklenburg side, knew something was wrong.
Boats that in past years glided in and out of the cove at an elevation of 96 feet - Duke's target for this time of year - were mired in mud lately.
"Seems to me that two feet of water is 'missing,'" a resident wrote to the Observer. Duke at first said visual inspections found nothing awry. Further investigation found the broken gauge Monday, spokeswoman Marilyn Lineberger said.
Duke said it doesn't know how far off the gauge was. Lineberger said the lake is believed to have fallen somewhere below the target, but higher than the minimum level - a difference of 1.7 feet. The mechanical gauge, mounted at the lake's dam, apparently went wrong when Duke drew down Mountain Island on April 21 for several days of work at the Riverbend power plant on the western shore. Duke's Web site, apparently in error, shows levels consistently above the target since April 25, as Duke refilled the lake.
Charlotte-Mecklenburg Utilities reported no problems drawing water from the lake, its chief water source.
There's no indication that gauges at other lakes are broken, Lineberger said.