The global coverage of freshwater resources within protected areas is poorly known due to a shortage of geographically-explicit data.  Some have suggested that the protected status of 12% of the Earth’s land surface likely protects an equivalent fraction of freshwater resources, but this claim is largely untested.  Coarse analyses relying on modeled freshwater habitat types have revealed gaps in protection, but corresponding  species distribution data are lacking.  We use well-developed databases for the State of Michigan to test the hypothesis that existing reserve networks, most which were designed to conserve terrestrial habitats and species, also offer adequate protection of aquatic resources.  Terrestrial protected areas included State and National Forests, State and National Parks, National Wildlife Refuges, and holdings of The Nature Conservancy and other land trusts.  Freshwater protected areas included waters covered by wild and scenic river statutes.  To evaluate coverage of aquatic resources within terrestrial reserves, we used databases on fish and mussel species richness, aquatic fauna of special concern, priority aquatic habitats, and ground water recharge zones.  Our analyses show that terrestrial reserves often protect important freshwater resources where aquatic considerations played a role in site selection.  However, there is poor correspondence in many areas, especially in heavily-settled parts of southern Michigan.