 Ongoing efforts in the Baltic Sea (Denmark, Sweden, Germany, Poland) and Long Island Sound and Puget Sound in the U.S. are currently examining nutrient uptake, cost-effectiveness, and potential environmental impacts of mussel farming as a means to mitigate excess nutrients and complement traditional wastewater treatment programs.In the United States and Canada, areas home to the most diverse freshwater mussel fauna in the world, there are 297 known freshwater mussel taxa.Of the 297 known species, 213 (71.7%) taxa are listed as endangered, threatened, of special concern.