Wyoming Framework Water Plan - Living Rivers Home Page

5.0 USE
beets, and beans are grown. Row crops make up about 13 percent of the crop distribution in the basin. In
the Wind/Bighorn River Basin, forage crops account for about 55 percent and small grains about 21
percent of the crops grown in the basin. Row crops make up a significant portion (24 percent) of the crop
distribution in this basin, and are found mostly in the Cody/Powell, Worland, Thermopolis, and
Riverton/Lander valleys.
Table 5-2 compares the statewide irrigated crop distribution from the 1973 Framework Plan to
that from the current seven basin plans. All irrigated crop types reported in the current basin plans show
increases in irrigated acreage and percent of crop distribution with the exception of grass/pasture. It
appears that there has been a shift away from grass/pasture to more alfalfa, row crops, and small grains,
which may be due, in large part, to the substantial increase in groundwater irrigation over the last 30
years. However, fluctuations in statewide crop distribution occur annually (even if on a small scale) and
over many years, and from the snapshot data available in the basin plans, one cannot automatically detect
trends in statewide crop distribution. Furthermore, changes in crop distribution, and thus any trends, tend
to occur in the valleys where there are more options for various crops, such as row crops, not in the higher
elevation areas where only forage crops can be grown. Crop distribution changes occur for various
reasons, including 1) water supply, 2) commodity prices and expenditures, and 3) labor costs and/or
intensity. Due to climatic and geographic conditions, and Wyoming’s livestock production, forage crops
will almost certainly continue to be the most extensive crops grown in the state in the future.
5.2.5 Diversions
Surface Water
Diversion records throughout the state of Wyoming are sparse. In none of the basins is every
diversion continuously recorded. In order to quantify irrigation depletions, each stream segment or
tributary where irrigation occurs would have continuous records of diversions and streamflow for a period
of 10 or 20 years (including dry, low streamflow and wet, high streamflow years); local weather stations
to accurately measure precipitation; and lysimeter (consumptive use) data obtained contemporaneously
with the streamflow and diversion records. For obvious economic and practical reasons, such is not the
case in Wyoming.
Estimates are necessarily made from incomplete records and sometimes inconsistent data. It is
not uncommon in various basins to find only a small percentage of diversions with well-maintained
measuring devices and/or prolonged periods of records. For instance, the Green River Basin Plan
reported, “less than ten percent of the irrigation canals in the basin had diversion records of sufficient
duration and detail to be of value in this analysis”. The Northeast Wyoming River Basin Plan stated,
“Unfortunately, there is very little available data on historical diversions in the Northeast Wyoming River
Basins planning area. Diversion records are available only for the Murray Ditch on Redwater Creek and
much of this irrigation is located in South Dakota, outside the limits of this planning study.” The
Northeast Basin Plan used the relationships between theoretical and actual water use based on diversion
records from the neighboring Powder/Tongue River Basin Plan.
On the other hand, the Bear River Basin Plan reported, “The Bear River Basin, because it
encompasses parts of three states and is governed by an interstate river commission, has excellent data
records. Records of streamflow and diversions are well maintained and extensive.” For the Bear River
Basin, complete daily diversion records in Wyoming were obtained for the 36 key ditch systems from the
Compact Engineer-Manager for 1971 through 1999.
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