North America has the world’s most diverse freshwater mussel fauna with approximately 300 species, but it is one of the most rapidly declining animal groups on the continent. The Nature Conservancy recognizes 55 percent of North America's mussel species as extinct or imperiled compared to only seven percent of the continent's mammal and bird species. In 2002, the Zoo began a lease on a 32-acre riverfront property for the purpose of establishing a facility dedicated to research and propagation of freshwater mussels. Since its start, the program has released thousands of juvenile mussels into Darby and Leading Creek waterways. This past year the facility raised $185,000 in grant money towards these and other efforts involving mussel conservation.