The amine salt of the compound endothall, 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid, has been used as a herbicide (HYDROTHOL) against submersed weeds in aquatic environments for a number of years, and its effects on aquatic systems are well understood. It has recently been found to be effective against zebra mussels, and a formulation has been registered as EVAC for molluscicidal use.