WDNR Says Dredging Will Restore Health of Gruber’s Grove Bay


WDNR Says Dredging Will Restore Health of Gruber’s Grove Bay

The Wisconsin Department of Natural Resources (WDNR) has issued a letter to the U.S. Army at Badger Army Ammunition Plant which supports dredging mercury-contaminated sediments that remain in Gruber’s Grove Bay on Lake Wisconsin. The January 23 letter says that additional dredging would restore the environmental health of the bay and achieve compliance with the Clean Water Act.

Despite two previous dredging actions by the Army, sediment sampling found mercury concentrations up to 9 parts per million (ppm), far above the cleanup goal of only 0.36 ppm. “In reviewing the dredging data it appears that much of the material dredged in 2006 was the higher density native materials that were located below the mercury-contaminated sediment,” WDNR wrote.

The WDNR believes that more modern dredging equipment and techniques will assure success this time. “We have successfully used dredging equipment to remove low density contaminated sediment on the Fox River, Sheboygan River and other sites,” WDNR said.

Citizens for Safe Water Around Badger (CSWAB), a group that for decades has pushed for bay cleanup, is pleased with the WDNR letter and with support from legislators including U.S. Senator Tammy Baldwin. “For more than 75 years, mercury contamination from Badger has poisoned fish and aquatic life in Lake Wisconsin,” said Executive Director Laura Olah.  “Safe removal of contaminated sediments will protect human health from ongoing exposures.”

During active production years, Badger Army Ammunition Plant discharged wastewater to Gruber’s Grove Bay of Lake Wisconsin resulting in the contamination of lake bottom sediments. In addition to mercury, sediment contaminants include lead, copper, arsenic, ammonia, nitroglycerine, PCBs and methylmercury – the most toxic form of mercury. Mercury is a highly toxic element and there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies.