Montana Tech student
Sandy Bruehl
prepares a sample of
well water for
analysis in
the laboratory.
Toward the BIG Picture of Montana’s Ground Water
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Montana, among the other states in the arid West, depends on water to sustain its population, livestock, and agriculture. Surface water supplies are well known and have been quantified since the last century. Montana’s subsurface water supply, its ground water, is less understood. Despite over 140,000 water wells constructed state wide since about 1860, much is still unquantified about one of the most essential elements of Montana’s economy. Moreover, because aquifers provide drinking water to more than 80 % of the State’s residents, many people are vitally interested in this resource. |
Montana Tech student |
An effort is underway to systematically inventory the State’s ground-water resources. Following a law passed by the 1991 Legislature, Montana has embarked on this first-ever assessment of all of its ground water. The Montana Bureau of Mines and Geology (MBMG) administers the program, and a steering committee, composed of members from other state and federal agencies, provides oversight and guidance. The assessment effort is the largest single project in the Bureau, and its goals are ambitious: over the next 30 years, teams of Bureau hydrogeologists and technicians (working cooperatively with field personnel from other agencies) will locate, measure, and sample thousands of water wells and interpret the data to characterize the availability, distribution, quality, and flow patterns of the State’s ground water. |
The assessment project is divided into three related, yet programmatically separate operations; the Characterization Program, the Monitoring Program, and the Ground-Water Information Center.
Characterization Program
The Characterization Program is mapping and describing many important parameters related
to water quality and water availability of individual aquifers in specific areas. To
accomplish this, the state has been divided into 29 areas, each of which can reasonably be
canvassed in a three-year study period. In each active area, geological and well-file
information is compiled to determine what is known about the aquifers. From the
compilation, Bureau hydrogeologists develop a general understanding (working model) of the
aquifers and assign field teams to collect ground-water data from selected wells. Finally,
the hydrogeologists evaluate the field data to modify the model. The number of wells
visited in each area varies depending on the goals of the specific study and the number of
aquifers. Ultimately, maps and illustrations of the various aquifers are generated
interpreting ground-water depth, flow direction, quality, and quantity.
The first study area is the five-county region near the North Dakota boarder called the Lower Yellowstone River Area (Dawson, Fallon, Prairie, Richland, and Wibaux counties). The second and third areas are Flathead Lake (1996) and Yellowstone and Treasure counties near Billings (1997); both areas have experienced unprecedented urban growth. In the Lower Yellowstone River Area, field work is essentially complete. Field teams have visited approximately 1,500 wells, collected about 180 water samples, and measured about 1,200 water levels. Additionally, researchers have determined the source aquifer in almost 8,600 wells. The data are being compiled, maps interpreting the data are being prepared, and a final report is expected in mid-1997.
Monitoring Program
A complementary operation of the assessment project is the Monitoring Program. This
program will produce long-term records of ground-water chemistry and water-level changes,
based on data periodically collected from a statewide network of about 1,000 monitoring
wells. The network is about 85% complete, with new monitoring points being established in
the Havre and Billings areas. Most wells in the network are measured quarterly, but the
network also includes approximately 40 recorders that produce hourly data. The detailed
information will help evaluate relationships between long-term climatic conditions and
ground-water storage.
Ground-Water Information Center
All data collected by the Characterization and the Monitoring programs are integrated with
similar information into the Bureau’s Ground-Water Information Center (GWIC) files
and data bases. Here they are readily accessible to agencies or individuals in various
formats ranging from personal contact (telephone calls) to paper, to digital (from disk to
network). GWIC serves as the link between the Characterization and the Monitoring programs
by providing a common point of storage for ground-water data that is easily accessible.
Much data gathered by other Bureau ground-water research, such as radon in water and
water-level data from wells near coal mines in Decker and Colstrip, also are stored in
GWIC. Data reposited in GWIC include location, well characteristics, depth, static-water
level, temperature, lithology, well yield, and water quality (inorganic chemistry). The
data bases currently have over fifty registered users, most from outside agencies. From
outside the Bureau, access to GWIC is gained by telephone or on the Internet.
The BIG Picture
No one will have to wait 20 years for ground-water answers. Already GWIC is servicing over
100 inquiries a month, excluding “dial up” access. As interpretations are
completed for each successive characterization area, maps and reports will be published
and become generally available to citizens, libraries, and local government officials
responsible for ground-water protection, management, and development. Additionally,
ground-water assessment staff will transfer the new knowledge to citizens, cities,
conservation districts, and state and federal agencies through open forums such as
lectures and poster presentations. The Bureau is logically and systematically creating the
BIG picture of Montana’s ground water. Many elements of that picture are and will be
available for immediate application through interim reports and access to the Ground-Water
Information Center.
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