The Free Press, Mankato, MN

January 30, 2013

Authorities issue warnings about retention ponds, aerated water

By Dan Nienaber
Free Press Staff Writer

— After Mankato Public Works employees noticed one of the city’s retention ponds had been shoveled off for an ice rink and decorated with a Christmas tree, they realized it was probably time to send a warning out to residents.

The city has surrounded many of its storm water ponds with parks and trails, making them a nice place to watch birds or toss rocks on a nice summer day. But  Public Works Director Mark Knoff wants residents to know those ponds shouldn’t be used for winter recreation.

Water from streets and sump pumps are flowing into the ponds, so the water under the ice is moving and often has salt and other chemicals in it. That means the ice is inconsistent and especially dangerous at inlets and outlets. That includes large ponds such as Lake Dorothy and the Lions Park pond.

“Although city staff work to make storm water ponds an aesthetic asset, they have a functional purpose and are not safe for recreational use,” Knoff said in a news release. “Our goal is to keep the public safe by providing information about how storm water ponds are used and why it’s important to not go on them.”

The pond with the tree, where people had been obviously skating, is near the intersection of Augusta and St. Andrew’s drives, said Mary Fralish, Public Works deputy director. She said there are 57 storm water ponds in the city. They are not marked as having unsafe ice.

Brown County officials also are putting out a warning for areas of county lakes that are marked as dangerous. After an incident where a car went through the ice on Lake Hanska last week, Sheriff Rich Hoffmann is reminding people not to drive in areas with warning signs for aeration systems.

Mankato Fire Deputy Director Jeff Bengtson offered reminders for anyone going out on a lake this winter. He suggested taking a rope, some type of floatation device or even a life jacket. He also said anyone on the ice should carry a pair of ice picks, preferably connected by a string that can be draped around the neck, that can be used to pull yourself out of the water if you break through the ice.

Bengtson and other firefighters use the picks, which can be purchased at sporting goods stores, when they practice ice rescues.

“They work incredibly well,” he said. “It’s very easy to pull yourself out of the ice with these picks and they could save your life. You lose dexterity almost immediately in that water. Your muscles contract.”