Perchlorate is highly soluble and chemically stable in water, which makes groundwater-contaminated plumes difficult to remediate by conventional treatment methods. To address the environmental impact of perchlorate, SERDP and ESTCP have funded work to improve the remediation of perchlorate-contaminated groundwater, evaluate the sources of perchlorate, assess alternatives to perchlorate as a long term solution, and study the toxicology of perchlorate to ecological receptors.