RESEARCH· ·1970·

eds of sandstone in the upper part of the Fox Hills
and lower part of the Hell Creek have an average
aggregate thickness of 90 feet. The aquifer, therefore,
would have an average permeability of about ( 1 '!~ 0 )
16 gpd per square foot.
CONCLUSIONS
The results of 49 flow and recovery tests in ~1ercer
nnd Oliver Counties indicate that sandstone beds within
the Fox I-Iills Sttndstone and Hell Creek Formation
have transmissivities that range from 13 to 3,100 gpd
per foot nnd average 510 gpd per foot. ~1any of the
wells on which ttquifer tests were mnde are completed
in the aquifer in the upper part of the Hell Creek
Formntion. Also, many wells do not entirely tap either
aquifer. Therefore, the nverage figure of 510 gpd per
:foot is not comparable to the figure for transmissivity
of 1,400 gpd per foot obtained by Darcy's law for the
nquifer in the upper Fox I-Iills Sandstone and lower
liell Creek Formation. The average of 16 gpd per ft 2
for permenbility obtained from the aquifer tests and
frmn the analysis of ground-water flow are in agreement.
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