Environmental Radiation Data (ERD) is compiled and published quarterly (five months after the quarter being monitored). The report includes data from the Environmental Radiation Ambient Monitoring System (ERAMS) and similar networks operated by contributing states. The ERAMS monitors environmental media for radioactive contaminants in air, precipitation, surface water, drinking water, and milk samples collected by state and local agencies throughout the United States. Specific radiochemical analyses include gross alpha, gross beta, gamma, tritium, 14C, 85Kr, 131I, 89-90Sr, 226Ra, 238-239Pu, and 234-235-238U. All data and associated 2 sigma counting errors are reported in standard units. Precision and accuracy of the data are ensured by duplicate analyses and participation in internal and external quality assurance programs.