Surface Water

Snake River Canyon

Five surface water samples and one duplicate sample were collected from locations throughout southeast Idaho and analyzed for tritium, gross alpha, and gross beta.   

Results for tritium analyses showed that only one sample (Idaho Falls) was above its 2s and MDC.  At the reported level, the tritium result is 83 times smaller than the SDWA limit, and 333 times smaller than the DCG value.

Analytical results for gross alpha showed that the samples from Bliss and Buhl exceeded their 2s and MDC values (Table 6).  At reported levels, the gross alpha values are between 13.6 and 16.5 times lower than the SDWA limit and between 27.3 to 33.0 times lower than the DCG value.

TABLE 6.        Surface water results > 2s and > MDC. 

Sample Results

Values for Comparison

 

Result (pCi/L) ± 2s

MDC (pCi/L)

SDWA (pCi/L)

DCG (pCi/L)

 Location

Gross Alpha

Buhl

1.10 ± 0.90

0.57

15

30

Bliss

0.91 ± 0.89

0.57

15

30

 

  Gross Beta

Bliss

5.83 ± 1.98

2.33

50

100

Buhl

5.49 ± 1.86

2.33

50

100

Buhl (duplicate)

5.12 ± 1.94

2.33

50

100

Hagerman

3.63 ± 1.76

2.33

50

100

Idaho Falls

2.98 ± 1.73

2.33

50

100

Twin Falls

6.50 ± 2.06

2.33

50

100

 

  Tritium

Idaho Falls

240.39 ± 72.61

104.81

2 x 104

8 x 104

Results for gross beta for all five surface water samples, and the duplicate from Buhl, were greater than their associated 2s and MDC values (Table 6).  Even at reported levels, the gross beta values are between 7.7 and 16.8 times lower than the SDWA levels, and between 15.4 to 33.6 times lower than DCG values.

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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