Table 35. (Continued) Island Well Enidrik Enidrik DDS1 ODS1 11-07-78 04-20-79 3.9 18 Nam Nam CTS1 CTS] 11-12-78 04-25-79 14 2 Nam NOTE: Date Salinity ppt CTS] 02-28-81 137¢5 90s, 239+240p,y pci/- pCi/L fFCI/L -5.3 -— -- 140 130 94 26 -- --- 140 250 16 -- 29 Dash indicates no data available. In general, the radionuclide concentrations in the groundwater lens reflect the average radionuclide concentrations in the soil above it. Eneu Island has a tremendous freshwater lens, the quality and volume of which is exceptional (Peterson and Underwood, 1987). On Eneu Island, the !3/cs, 90sr, and 239+240py concentrations in the ground water are low and in all cases below the EPA guidance of 8 pCi/L for 90sr, 91 pCi/L for !37Cs, and 15 pCi/L for transuranic radionuclides for drinking water (based on 2 L/d intake and a 4 mrem/y limit) (40 CFR 141.15). On the other hand, the 9Sr concentration for Bikini Island generally exceeds the EPA guideline. However, in most cases, Bikini Island ground water is so saline that it is nonpotable. The salinities in the ground water on Bikini and Eneu Islands have increased since 1975; this observation will be dealt with in more detail in the Discussion section of this report. The radionuclide concentrations are very low in the collected rainwater (cistern water), which is the major source of fresh water for the island residents. All the measured concentrations from 1975 to 1984 are well below Current EPA guidelines for drinking water. In 1978, when the people radionuclide concentrations in were relocated cistern from Bikini water increased as Atoll, a the result of vegetation that grew around the cisterns at heights well above the top of the cisterns. Consequently, considerable vegetation containing !37Cs started falling in openings in the top of the cisterns and accumulating in the bottom. 57