Geohydrology of the Idaho
National Engineering and
Eastern Snake River Plain, Idaho
Index of Subjects
In 1949, the U.S. Atomic Energy Commission, which later became the U.S.
Department of Energy, requested that the U.S. Geological Survey (USGS)
describe the water resources of the area now known as the Idaho National
Engineering and Environmental Laboratory (INEEL) (fig. 1). The purpose of
the result-ing study was to characterize these resources before the
development of nuclear-reactor testing facilities. The USGS since has
maintained a monitoring network at the INEEL to determine hydrologic trends
and to delineate the movement of facility-related radiochemical and
chemical wastes in the Snake River Plain aquifer. This fact sheet,
summarized from two published reports (Anderson and others, 1996;
Bartholomay and others, 1997), describes the geohydrology of the eastern
Snake River Plain (fig. 1) at the INEEL.
(Larger Version, 195K GIF)
Figure 1. Location of the Idaho National Engineering and
Environmental laboratory (INEEL), Idaho.|
The Snake River Plain aquifer is one of the most productive aquifers in the
United States (U.S. Geological Survey, 1985, p. 193). Recharge to the
Snake River Plain aquifer is principally from infiltration of applied
irrigation water, infiltration of streamflow, and ground-water inflow from
adjoining mountain drainage basins. Some recharge may be from direct
infiltration of precipitation, although the small amount of annual
precipitation on the plain (8 inches at the INEEL), evapotranspiration, and
the great depth to water (in places exceeding 900 feet) probably minimize
this source of recharge.
The Big Lost River (fig. 2) drains more than 1,400 square miles of
mountainous area that includes parts of the Lost River Range and Pioneer
Range west of the INEEL. Flow in the Big Lost River infiltrates to the
Snake River Plain aquifer along its channel and at sinks and playas at the
river's terminus. To avoid flooding at the INEEL facilities, excess runoff
has been diverted since 1958 to spreading areas in the south-western part
of the INEEL, where much of the water rapidly infiltrates to the aquifer.
Other surface drain-ages that provide recharge to the Snake River Plain
aquifer at the INEEL include Birch Creek, Little Lost River, and Camas
(Larger Version, 194K GIF)
Figure 2. Location of selected geographical features and
facilities in proximity to the Idaho National Engineering and
Environmental Laboratory, Idaho.|
The average streamflow in the Big Lost River below Mackay Reservoir (fig.
2) for the 79-year period of record (water years 1905, 1913-14, and
1920-95) was 222,900 acre-feet per year (Brennan and others, 1996, p.
217). During 1992-95, streamflow in the Big Lost River below Mackay
Reservoir ranged from 125,900 acre-feet (56 percent of average flow) during
the 1992 water year (Harenberg and others, 1993, p. 178) to 310,000
acre-feet (139 percent of average flow) during the 1995 water year (Brennan
and others, 1996, p. 217). Streamflow recorded for the Big Lost River
near Arco during 1993 and 1995 was 10,610 and 84,880 acre-feet per year,
Before 1989, recharge to the Snake River Plain aquifer downstream from Arco
was substantial because of infiltration of streamflow from the Big Lost
River channel, diversion areas, sinks, and playas. For example, measured
infiltration losses at various discharges ranged from 1 to 28 cubic feet
per second per mile (Bennett, 1990, p. 1). Combined discharge in the Big
Lost River below the INEEL diversion near Arco and the INEEL diversion at
its head near Arco was 7,777 acre-feet per year in 1993 (Harenberg and
others, 1994, p. 210, 212) and 80,080 acre-feet per year in 1995 (Brennan
and others, 1996, p. 221, 223). No streamflow occurred in the Big Lost
River downstream from Arco during 1992 and 1994.
The Snake River Plain aquifer consists of a thick sequence of basalts and
sedimentary interbeds filling a large, arcuate, structural basin about 200
miles long and 50 to 70 miles wide in southeastern Idaho. The INEEL is on
the west-central part of the eastern Snake River Plain. The INEEL is
underlain by hundreds of basalt flows, basalt-flow groups, and sedimentary
interbeds; basalt makes up about 90 percent of the volume of deposits in
the unsaturated zone and the aquifer in most areas. A basalt flow is a
solidified body of rock that was formed by a lateral, surficial outpouring
of molten lava from a vent or fissure (Bates and Jackson, 1980). A
basalt-flow group consists of one or more distinct basalt flows deposited
during a single eruptive event (Kuntz and others, 1980). All basalt flows
of each group erupted from the same vent or vents and have similar ages,
paleomagnetic properties, potassium contents, and natural-gamma emissions
(Anderson and Bartholomay, 1995). The basalt flows, which locally are
altered (Fromm and others, 1994), consist mainly of medium- to dark-gray
vesicular to dense olivine basalt. Individual flows are as much as 100
feet thick and in places are interbedded with cinders and thin layers of
sediment. Sedimentary interbeds, which are most abundant between flow
groups, accumulated on the ancestral land surface for hundreds to hundreds
of thousands of years during periods of volcanic quiescence. Sedimentary
interbeds are as much as 50 feet thick and consist of well to poorly sorted
deposits of clay, silt, sand, and gravel. In places the interbeds contain
cinders and basalt rubble.
The basalt and sediment underlying the INEEL are saturated at depth and
together form the Snake River Plain aquifer. Depth to water at the INEEL
ranges from about 200 feet below land surface in the northern part to about
900 feet in the southern part (Ott and others, 1992); the general direction
of ground-water flow is northeast to southwest at an average hydraulic
gradient of about 4 feet per mile. The effective base of the aquifer at
the INEEL generally coincides with the top of a thick and widespread layer
of clay, silt, sand, and altered basalt that is older than about 1.6
million years (Anderson and Bowers, 1995). The top of this layer ranges in
depth from 815 to 1,710 feet below land surface in the western half of the
INEEL. The effective saturated thickness of the aquifer ranges from about
600 feet near Test Area North to about 1,200 feet near the Idaho Chemical
Processing Plant and the Radio-active Waste Management Complex (fig. 2).
Saturated thickness in the eastern half of the INEEL may be greater than
1,200 feet. Hydraulic properties of the aquifer differ considerably from
place to place depending on saturated thickness and the character-istics of
the basalt and sediment. In places, the basalt and sediment in the
uppermost part of the aquifer yield thousands of gallons per minute of
water to wells, with negligible drawdown (Ackerman, 1991). Hydraulic data
for the basalt, sediment, ash, and tuff underlying the aquifer are sparse,
but data from a deep test well indicate that these deposits are relatively
impermeable compared with the aquifer (Mann, 1986). Localized zones of
perched ground water, which are attributed mainly to infiltration of water
from unlined percolation ponds and recharge from the Big Lost River, are
present in basalt and sediment overlying the Snake River Plain aquifer
(Cecil and others, 1991).
Water in the Snake River Plain aquifer moves prin-cipally through fractures
and interflow zones in the basalt. A significant proportion of the ground
water moves through the upper 200 to 800 feet of basaltic rocks (Mann,
1986, p. 21). Ackerman (1991, p. 30) reported a range of transmissivity
of basalt in the upper part of the aquifer from 1.1 to 760,000 feet2 per
day. The hydraulic conductivity of underlying rocks is 0.002 to 0.03 feet
per day, several orders of magnitude smaller (Mann, 1986, p. 21).
Ground water moves southwestward from the INEEL and eventually is
discharged to springs along the Snake River downstream from Twin Falls, 100
miles southwest of the INEEL. About 3.7 million acre-feet of ground water
was discharged to these springs in 1995.
Ackerman, D.J., 1991, Transmissivity of the Snake River Plain aquifer at
the Idaho National Engineering Laboratory, Idaho: U.S. Geological Survey
Water-Resources Investigations Report 914058 (DOE/ID-22097), 35 p.
Anderson, S.R., Ackerman, Daniel J., Liszewski, M.J., and Freiburger, R.M.,
1996, Stratigraphic data for wells at and near the Idaho National
Engineering Laboratory, Idaho: U.S. Geological Survey Open-File Report
96-248 (DOE/ID-22127), 27 p. and 1 diskette.
Anderson, S.R., and Bartholomay, R.C., 1995, Use of natural-gamma logs and
cores for determining stratigraphic relations of basalt and sediment at the
Radioactive Waste Management Complex, Idaho National Engineering
Laboratory, Idaho: Journal of the Idaho Academy of Science, v. 31, no. 1,
Anderson, S.R., and Bowers, Beverly, 1995, Stratigraphy of the unsaturated
zone and uppermost part of the Snake River Plain aquifer at Test Area
North, Idaho National Engineering Laboratory, Idaho: U.S. Geological Survey
Water-Resources Investigations Report 954130 (DOE/ID-22122), 47 p.
Bartholomay, R.C., Tucker, B.J., Ackerman, D.J., and Liszewski, M.J., 1997,
Hydrologic conditions and distribution of selected radiochemical and
chemical constituents in water, Snake River Plain aquifer, Idaho National
Engineering Laboratory, Idaho, 1992 through 1995: U.S. Geological Survey
Water-Resources Investigations Report 97-4086 (DOE/ID-22137), 57 p.
Bates, R.L., and Jackson, J.A., eds., 1980, Glossary of geology (2d ed.):
Falls Church Va., American Geological Institute, 749 p.
Bennett, C.M., 1990, Streamflow losses and ground-water level changes along
the Big Lost River at the Idaho National Engineering Laboratory, Idaho:
U.S. Geological Survey Water-Resources Investigations Report 904067
(DOE/ID-22091), 49 p.
Brennan, T.S., O'Dell, I., Lehmann, A.K., and Tungate, A.M., 1996, Water
resources data, Idaho, water year 1995-volume 1. Great Basin and Snake
River Basin above King Hill: U.S. Geological Survey Water-Data Report
ID-95-1, 452 p.
Cecil, L.D., Orr, B.R., Norton, T., and Anderson, S.R., 1991, Formation of
perched ground-water zones and concentrations of selected chemical
constituents in water, Idaho National Engineering Laboratory, Idaho,
1986-88: U.S. Geological Survey Water-Resources Investigations Report
91-4166 (DOE/ID-22100), 53 p.
Fromm, J.M., Hackett, W.R., and Stephens, J.D., 1994, Primary mineralogy
and alteration of basalts and sediments in drillcores from the Idaho
National Engineering Laboratory, eastern Snake River Plain [Abs.]:
International Symposium on the Observation of the Continental Crust Through
Drilling, VIIth, Santa Fe, N. Mex., April 25-30, 1994 [Abstracts],
Harenberg, W.A., Jones, M.L., O'Dell, I., Brennan, T.S., Lehmann, A.K., and
Tungate, A.M., 1993, Water resources data, Idaho, water year 1992-volume 1.
Great Basin and Snake River Basin above King Hill: U.S. Geological Survey
Water-Data Report ID-92-1, 377 p.
-----1994, Water resources data, Idaho, water year 1993-volume 1. Great
Basin and Snake River Basin above King Hill: U.S. Geological Survey
Water-Data Report ID-93-1, 401 p.
Kuntz, M.A., Dalrymple, G.B., Champion, D.E., and Doherty, D.J., 1980,
Petrography, age, and paleomagnetism of volcanic rocks at the Radioactive
Waste Management Complex, Idaho National Engineering Laboratory, Idaho,
with an evaluation of potential volcanic hazards: U.S. Geological Survey
Open-File Report 80-388, 63 p.
Mann, L.J., 1986, Hydraulic properties of rock units and chemical quality
of water for INEL1-a 10,365-foot deep test hole drilled at the Idaho
National Engineering Laboratory, Idaho: U.S. Geological Survey
Water-Resources Investigations Report 864020 (IDO22070), 23 p.
Ott, D.S., Edwards, D.D., and Bartholomay, R.C., 1992, Water-level data for
selected wells on or near the Idaho National Engineering Laboratory, Idaho,
1983 through 1990: U.S. Geological Survey Open-File Report 92643
(DOE/ID-22105), 307 p.
U.S. Geological Survey, 1985, National water summary, 1984-Hydrologic
events, selected water-quality trends, and ground-water resources: U.S.
Geological Survey Water-Supply Paper 2275, 467 p.
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For More Information|
USGS State representative
230 Collins Road
Boise, ID 83702
Fax: (208) 387-1372
INEEL Project Office
INEEL, MS 4148
P.O. Box 2230
Idaho Falls, ID 83403
Fax: (208) 526-6002
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