Wyoming Framework Water Plan - Living Rivers Home Page

4.0 RESOURCES
very low solubilities of the constituent minerals.
Where aquifers receive recharge from the surface, they are potentially subject to contamination.
In 1998, the University of Wyoming completed a statewide study of groundwater contamination potential
that assessed seven factors, including depth to groundwater and recharge rates, to produce 1:100,000 scale
county-by-county maps. Figure 4-11 presents a statewide version of this mapping of “Aquifer
Sensitivity”. Rankings are relatively-high, medium, and low and carry no specific units. The most
sensitive lands are those where a contaminant at the surface such as a spill, overapplication of agricultural
chemicals, or septic systems can most easily enter the aquifer. The alluvial aquifers are most sensitive.
Least sensitive are bedrock aquifers where substantial thicknesses of low-permeability material lie above
them.
The Snake/Salt Basin Plan extended the vulnerability concept to rural septic systems, a common
source of nitrate input to groundwater. The density of rural domestic wells was mapped, looking to a
general, rule-of-thumb of 2 acres/lot (20 lots per quarter-quarter section) as the threshold beyond which
septic system contamination may be of concern.
4.4.5 Groundwater Associated with Energy Development
For many decades, groundwater has been produced along with oil and gas from Wyoming’s
relatively “wet” oilfields. For example, in the Wind/Bighorn Basin, annual production of 331 ac-ft of coproduced
groundwater was estimated (WOGCC, 2000). This water has been discharged to the surface as
a by-product of mineral production; used for oil field water flood; or, due to increasing environmental
concerns, reinjected.
Starting in the 1990s, the production of groundwater in association with mineral production has
vastly increased through the development of CBM wells. Unlike the groundwater produced incidentally
with oil and conventional gas production, groundwater production is the driving force in CBM.
Groundwater production on the order of 5-15 gpm per well is used to lower groundwater pressure to bring
dissolved and adsorbed methane into the well. The produced water is typically discharged to the surface,
although water quality concerns are generating increasing consideration of reinjection. Figure 4-12
presents State Engineer’s Office permitted CBM wells as of December, 2006. Obviously, the Powder
River Basin has been the focus of activity to date. Development is far from complete in that basin and
has recently been extending to other basins. Because CBM accompanies coal seams and coal seams are
present in all Wyoming basins, there is potential for CBM development throughout the state. Permitting
activity beyond the Powder River Basin is just beginning and is expected to grow considerably in the near
future.
Wyoming has limited potential for groundwater geothermal energy development. Various sites
with low-grade geothermal resources have developed commercial applications through spa-type uses.
The Snake/Salt Basin Plan discusses the potential for development of the higher-grade geothermal
potential of far western Wyoming.
4.5 REFERENCES
Colorado Geological Society. 2003. Ground Water Atlas of Colorado.
Curtis, Jan, and Grimes, Kate. 2004. Wyoming Climate Atlas.
Love and Christiansen. 1985. Geologic Map of Wyoming.
Wyoming Oil and Gas Conservation Commission. 2000. 2000 Wyoming Oil and Gas Statistics.
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