The Freeborn County Environmental Services Department put up sign poles this weekend warning of thin ice around aerators in Albert Lea Lake.

Monday, January 07, 2002

The Freeborn County Environmental Services Department put up sign poles this weekend warning of thin ice around aerators in Albert Lea Lake.

The 30 poles were placed on the ice to the west of the I-35 bridge. Two 250-foot long, underwater tubes connected to air compressors will be activated this week, which will create open water above.

The signs standing at 75-foot intervals enclose the 350-foot wide and 500-foot long ice surface.

Three employees from the Environmental Services Department and a USDA officer opened holes on an eight-inch layer of ice and placed the poles.

The aerators laid last fall by the department are expected to prevent lower oxygen levels in the lake. The lack of oxygen during winter when the lake is covered with ice and snow could invite a massive fish kill.

The device will help decomposition of bottom sediments by providing oxygen to bacteria living in the water. The sediments are considered to be one of a major cause affecting the water quality, according to the Environmental Health Coordinator Richard Hoffman.

The open water created by the aerators will also help the lake bottom to receive sunshine during the icy season, which will encourage photosynthesis for water vegetation and increase the oxygen level.

The Environmental Services Department will monitor the oxygen level throughout the winter and also measure the thickness of the sediment layer at the end of the season to assess the effect of the device.