Two new groundwater well sites, FWR 5 and FWR 6, were established on Eneu Island during January 1977. The groundwater at these locations has low salinities and is of acceptable chemical quality but 9°Sr concentrations at FWR 5 exceeds the recommended EPA guideline of 8 pCi/1?. FWR 4 is the main skimming well supplying groundwater for use on Eneu at the present time. The groundwater from this well is chemically acceptable for household and drinking purposes. The concentrations of 137Cs, 9%Sr and 233+24°Py in the water, however, have been variable since 1975 and during January 1977, the 9°Sr concentration was found to exceed the recommended EPA guideline of 8.pCi/1. The radionuclide concentrations in the groundwater at FWR 4 do not appear to change systematically. 137Cs concentrations decreased between 6/75 and 1/77, while 2°Sr and 239t240py concentrations increased. Between 1/77 and 11/77, both 137Cs and 239*2*9py essentially doubled in concentration. We are attempting to correlate these changes in concentration with fresh water recharge from rainfall, groundwater residence times and other hydrological: features. The two cisterns attached to the old mess hall are presently the only aboveground storage facilities for rainwater on Eneu Island. The water in the cisterns is, of course, chemically acceptable for drinking and contains levels of '37Cs and 2°Sr lower than cisterns water samples collected from ° Bikini Island. The 99Sr concentration in the Eneu cistern water is similar to the average levels reported for New York tap water (0.30 pCi/1) during 1977 (Environmental Measurements Laboratory Report, EML-339, April 1978). wee LO124Bb —