Wyoming Framework Water Plan - Living Rivers Home Page

7.0 AVAILABILITY
the substantial benefits of more stable chemistry, much reduced treatment requirements, higher winter
temperatures, etc. Similarly, a decision on development of additional water supplies as groundwater or
surface water may depend on the availability of project funding, which may vary by water source. Where
surface flows are adequate to meet demands on average, but may be seasonally inadequate or may be
compromised by short-term drought cycles, use of the alluvial groundwater reservoir may be useful to
modulate variations in the availability of surface water resources over time.
The most abundant supply of undeveloped alluvial groundwater appears to be in the Snake/Salt
Basin, particularly in the Snake River Aquifer in Teton County. Given the abundance of available surface
water in that basin, conflicts with surface water are not expected to be a major constraint on groundwater
development. In the Platte Basin, in contrast, surface water connection is addressed by the Modified
North Platte Decree and the recently finalized Platte River Recovery Implementation Program (PRRIP),
and presents a major limitation on future development. Maps have been developed of those portions of
the Platte River Basin that, upon initial investigation, appear to produce depletions less than the
“hydrologically connected’ criteria. In areas more closely associated with stream depletions, major
additional development of groundwater in the Platte Basin is likely to come primarily through trade or
replacement arrangements with respect to surface water.
In summary, the above approaches to estimate the amount of groundwater in storage and the total
recharge to groundwater provide upper bounds on the possible supplies of mineable groundwater and
sustainable groundwater production, respectively. As a practical matter, however, the available
groundwater supply is substantially less.
7.2.5 Groundwater Quality
Most water uses have some sensitivity to water quality. Thus,
groundwater availability also will be a function of how the quality from a
particular aquifer and location aligns with the needs of a particular use.
As explained in Chapter 4, natural groundwater quality is generally best
closest to outcrop and deteriorates the longer groundwater has been in
contact with aquifer minerals. This effect is weakest in the “major
aquifers” of Figure 4-9 and strongest in the “minor” and “marginal”
aquifers.
For the most part, Wyoming has been relatively free of
widespread human impacts to groundwater quality. Beyond conflicts
associated with relatively high concentrations of nitrates in water supply
wells around Torrington, generally understood to result from application
of crop fertilizer, groundwater contamination issues in Wyoming have
largely been confined to local incidents of spills and leaks. These
incidents have compromised the availability of groundwater in local areas
but rarely have had widespread effects.
As discussed in Chapter 4, certain Wyoming aquifers are more susceptible to contamination than
others. The alluvial aquifers are generally the most productive, but due to their relatively high
permeabilities, exposure at the surface, and location along developed stream corridors, they are more
subject to water quality impacts from surface uses.
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