Wyoming Framework Water Plan - Living Rivers Home Page

5.0 USE
The first filings in Wyoming for instream flow rights were for protection of various species of
cutthroat trout. There are currently 100 instream flow applications filed with the State, with 66 having
been permitted as of December 2006. Instream flow filings for rivers and streams in the state are shown
in Figure 5-10.
Reservoir Minimum Pools
Several reservoirs in the state have storage permitted for a variety of environmental uses. These
uses, as they appear on the water rights, include fish or fish and wildlife. Recreational uses defined on
permits can be considered environmental to the extent that water in storage for recreational purposes, and
not released for other consumptive or nonconsumptive uses, can be beneficial, in an environmental sense,
for fish habitat and wildlife consumption. Reservoirs with permitted capacity for stock water similarly
serve a dual environmental function.
"Conservation storage" describes all of the storage capacity allocated for beneficial purposes and
is usually divided into active and inactive areas or pools. "Active storage" or “Active conservation pool”
refers to the reservoir space that can actually be used to store water for beneficial purposes. Each
reservoir has an allocation for an active conservation pool, which holds reservoir inflow for such uses as
irrigation, power, municipal and industrial, fish and wildlife, navigation, recreation, and water quality.
Inactive storage refers to water beneath the lowest outlet structures where water cannot be released by
gravity and to areas expected to fill up with sediments. This storage is often needed to increase the
efficiency of hydroelectric power production.
Direct Wildlife Consumption
There are no current estimates of consumptive water use by wildlife for six of the river basin
planning areas. An estimate developed for the Green River Basin puts consumptive use by big game and
wild horses at about 500 acre-feet of water annually. It was assumed in the Powder/Tongue River Basin
and in the Northeast Wyoming River Basin studies that a similar figure would be roughly correct for
those basins. If all river basin planning areas are assumed to be similar to the Green River Basin, use
would be about 3,500 acre-feet annually. This level of consumptive use is relatively small and is not
expected to change significantly over the planning horizon.
Threatened and Endangered Species
The presence of threatened or endangered species of plants and animals, or of species that might
be considered for such listing, can make water management and development more complex. A number
of species in Wyoming are so listed by the U.S. Fish and Wildlife Service. Section 2(c)(2) of the
Endangered Species Act requires state and local agencies to cooperate with federal agencies in issues
involving such species. Particularly in cases in which federal land is involved, such cooperation means
conducting wildlife and plant studies of the targeted area. Some examples of animal species include the
grizzly bear, whooping crane, Kendall Warm Springs dace, bald eagle, black-footed ferret, lynx, Preble’s
meadow mouse, pike minnow (squawfish), razorback sucker, Wyoming toad, and gray wolf. Some listed
plant species are Colorado butterfly plant, blowout penstemon, Ute ladies’ tress, and desert yellowhead.
There are also other species that have been proposed for addition to the threatened list, and a long list of
candidates (258 species) for endangered or threatened status.
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