IDNR: Gate failure on Upper Dam repaired, water levels coming back to normal

Shaw Local

ROCK FALLS – The IDNR and the Rock Falls Electric Department quickly identified and repaired a mechanical failure at the Rock River’s Upper Dam that caused gates to open and sent water levels above the dam plummeting up to a foot.

Those levels should be back to normal by Tuesday, Jayette Bolinsk, the Illinois Department of Natural Resources director of communications, said in an email sent around 12:30 p.m. Monday.

According to the email:

A disconnect switch in the transformer that supplies power to the dam control building failed around 3 a.m., causing a power outage. The back-up generator kicked in, and ran for about three hours before it overheated for some unknown reason and shut down.

The ensuing power failure caused the compressors that supply air to the dam to stop operating, allowing the gates to open.

The city repaired the transformer disconnect switch around 10:30 a.m., restoring the power and getting operations back to normal.

“Gates are being raised, and over the next several hours will return to their normal operating elevation, and upstream water levels should return to normal over the next 24 hours,” Bolinski said in the email.

Until then, the Rock River upstream of the dam will be 6 inches to a foot lower than normal.

The Hennepin Canal also was affected.

“The [dam] controls water elevation in the Hennepin Canal. The pool upstream of the dam has dropped about 12 inches since the back-up generator failed.

“This will directly affect the canal, and it would be expected that water elevations in the canal will be 8 inches to 12 inches lower than normal. Water levels in the canal will return to normal over the next 24 hours as the dam gates are returned to normal operating elevations,” the email said.

Oppold Marina in Sterling is closed to most boat launches, depending on the type and size of the boat, until the river level normalizes, Park District Executive Director Larry Schultd said.

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