Water Sampling

The ESER program samples precipitation, surface water, and drinking water. Monthly composite precipitation samples are collected from Idaho Falls and the Central Facilities Area (CFA) on the INEEL. Weekly precipitation samples are collected from the Experimental Field Station (EFS) on the INEEL. Surface and/or drinking water are sampled twice each year at 19 locations around the INEEL. This occurs during the second and fourth quarters. The results of the second quarter sampling are reported here.

Precipitation Sampling

Precipitation samples are gathered when sufficient precipitation occurs to allow for the collection of the minimum sample volume of approximately 20 mL. Samples are taken of a monthly composite from Idaho Falls and CFA, and weekly from the EFS. Precipitation samples are analyzed for tritium. Storm events in the second quarter of 2002 produced only minimal precipitation yielding a total of five samples – two from the EFS and CFA, and one from Idaho Falls.

No tritium was measured above the sample’s 2s value in any of the samples collected during the second quarter 2002. Data for all second quarter 2002 precipitation samples collected by the ESER Program are listed in Table C-6 (Appendix C).

Drinking Water

Fourteen drinking water samples and one duplicate were collected from selected taps throughout southeast Idaho (Figure 11 below). Samples were analyzed for gross alpha, gross beta, and tritium (3H). None of the water samples exceeded their respective 2s value for gross alpha.

Figure 11. Drinking and Surface Water Sampling Locations.

Of the fifteen water samples collected all but four (Arco, Atomic City, Carey, and Howe) exceeded their 2s value for gross beta (Table 2). The EPA Safe Drinking Water Act (SDWA) limits gross beta in drinking water based on an annual exposure of 4 mrem/yr. Since data are reported from the laboratory as a concentration (i.e., pCi/L) a screening concentration of 50 pCi/L is used to meet this level (Appendix B-1). The maximum concentration of gross beta detected was from Minidoka and was lower than the SDWA screening value. Levels of gross beta observed in drinking water are not unusual given the basaltic terrain (USGS 1991). All values are similar to those recorded in previous years, and are well below the levels outlined for drinking water protection (Appendix B-1). All drinking water sample results may be found in Appendix C,
Table C-7.

Table 2. Drinking water tritium and gross beta results greater than (>) 2s.

	Sample Results^a		Limits for Comparison^a
Location	Result ± 2s	MDC	SDWA	DOE DCG
Tritium
Aberdeen	349.90 ± 71.54	128.46	20,000	2 x 10⁶
Howe	316.54 ± 71.08	128.46	20,000	2 x 10⁶
Gross Beta
Aberdeen	2.80 ± 2.05	3.24	15	100
Duplicate	4.54 ± 2.02	3.01	15	100
Fort Hall	3.67 ± 2.09	3.25	15	100
Idaho Falls	3.58 ± 1.82	2.73	15	100
Minidoka	2.20 ± 1.92	3.09	15	100
Monteview	8.74 ± 2.52	3.50	15	100
Moreland	7.25 ± 2.46	3.49	15	100
Mud Lake	3.38 ± 1.61	2.41	15	100
Roberts	4.28 ± 1.82	2.69	15	100
Shoshone	1.98 ± 1.89	3.04	15	100
Tabor	4.71 ± 1.93	2.83	15	100
a. All values shown are in picocuries per liter (pCi/L).

Only the Howe and Aberdeen samples exceeded their 2s values for tritium. The SDWA limits tritium in drinking water to 2 x 10⁴ pCi/L (Appendix B-1). The concentration of tritium detected in these samples was many times lower than the SDWA limit. The measured levels were also within the range of natural tritium that exists in the Snake River Plain Aquifer and throughout the world. Low levels of tritium exist in the environment at all times. The major natural source of tritium is cosmic ray reactions in the upper atmosphere. From 1978 to 2001 the EPA, as part of its ERAMS, measured tritium from -9.00 x 10¹to 1.00 x 10³ pCi/L in drinking water samples across the United States (EPA, 2002).

Surface Water

Five surface water samples and one duplicate sample were collected from locations throughout southeast Idaho and analyzed for tritium, gross alpha, and gross beta. None of the samples were greater than their respective 2s values for either tritium or gross alpha activity.
Three of the five surface water samples were greater than their associated 2s values for gross beta (Table 3). Even at reported levels, the gross beta values are lower than the SDWA screening value of 15 pCi/L and the DCG values (Appendix B-1).

Table 3. Surface water gross beta results greater than (>) 2s.

The presence of gross alpha and gross beta in surface water (particularly the springs) is typically related to dissolution of naturally occurring radionuclides (i.e., uranium, radium, potassium) by groundwater as it flows through the surrounding basalts (USGS, 1991). Levels of gross alpha and gross beta in all samples are similar to results from recent years. All gross alpha and gross beta results can be found in Appendix C, Table C-7.

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