For more than 7 years, CSWAB has led a steadfast and determined campaign for the complete cleanup of toxic muck in Gruber’s Grove Bay and on November 26, the WDNR announced the completion of the project.

“The river system is better off because Gruber’s Grove Bay is an important asset to not only residents living on the bay but to others using Lake Wisconsin,” said Hank Kuehling, a hydrogeologist with the WDNR.

More than 60,000 cubic yards of sediment harboring mercury, methyl mercury, lead and copper were removed over the past four months from the 17-acre project area in the bay.  The contamination was caused by the discharge of as much as 25 million gallons of wastewater per day directly into the bay from 1942 to 1976.

The Army’s contractor began dredging the bay in July 2006 and finished in early November. The sediment was pumped with water from the bay into 42 geo-membrane tubes placed on a plastic liner on BAAP land where it will be covered with a final soil cap next year, the WDNR said.

The bay was dredged once before, in 2001, and 90,000 cubic yards of contaminated sediment was removed and de-watered.  After the project was complete, sampling conducted by WDNR staff found that mercury (and other metals) were still present in sediments throughout the bay at levels above the clean-up goal.

WDNR staff estimate that the mass of contaminants taken out of the bay, based on the 150,000 cubic yards of sediment removed by the two dredging operations, totals 500 pounds of mercury, 12,000 pounds of copper, 16,000 pounds of zinc, and 36,000 pounds of lead.

The cleanup of the bay is a great success that speaks to the importance of community involvement.  CSWAB will be following up on the project, including pressing for water column testing and urging the WDNR to go back in a few years to see if the aquatic life cycle in Gruber’s Grove Bay has recovered.  CSWAB will continue to advocate for cleanup of mercury contamination that likely moved outside the bay and was not part of these cleanup efforts.

Thank you to everyone that helped make this success possible!