Wyoming Framework Water Plan - Living Rivers Home Page

5.0 USE
Table 5-1 Irrigated Acreage
River Basin
Current Irrigated Lands 2
Surface
1973 Total Total
Water Groundwater
acres
Bear 59,000 64,000 --- ---
Green 3 332,000 331,100 330,980 120
Northeast Wyoming 3 161,000 77,600 59,600 18,000
Platte 553,000 613,000 --- ---
Powder/Tongue 3 See Note 1 161,400 161,180 220
Snake/Salt 94,000 99,000 --- ---
Wind/Bighorn 4 539,000 601,000 --- ---
Total 1,738,000 1,961,000 --- ---
1
In the 1973 Framework Plan, Powder/Tongue Basin is included in Northeast Wyoming Basin. Also, the 1973 Wind/Bighorn
Basin included the Little Bighorn subbasin, but the Little Bighorn is in the 2002 Powder/Tongue Basin.
2 Current irrigated acreage listed for primary source of supply. Idle lands identified in the Northeast Wyoming and
Powder/Tongue basins are not included.
3 Only Green, Northeast, and Powder/Tongue River Basin Plans distinguished between surface water and groundwater
irrigated acreage.
4 Current Wind/Bighorn figure is modeled irrigated acreage for full-supply scenario and does not include Popo Agie Basin or
Tribal Futures Projects.
The nearly 2 million total irrigated acres are approximately 225,000 acres more than was
estimated in 1973, a 13 percent increase. The increase came from the Northeast Wyoming, Platte,
Powder/Tongue, and Wind/Bighorn River Basins, which, combined, accounted for approximately
217,000 acres of the total increase.
The large increase in irrigated acreage over the past 30 years may be due to one or more reasons,
including 1) new permitted, surface water irrigated acreage (likely to be a small percentage); 2) an
increase in already permitted, surface water irrigated acreage (some lands with permitted surface water
rights have not been irrigated but still have valid water rights and may be irrigated); 3) a substantial
increase in groundwater irrigated acreage (new lands that were irrigated with groundwater which were
previously not irrigable by surface water sources); and 4) inconsistent accounting of irrigated acreage
between the 1973 Framework Plan and the recent basin plans (a different accounting of recently irrigated,
idle, subirrigated, etc. lands).
5.2.4 Irrigated Crops
Another essential part of estimating the amount of water used for irrigation is the irrigated crop
distribution. Crop evapotranspiration (ET), irrigation water requirements (IWR), and irrigation methods
can vary by crop type. An accurate assessment of crop distribution is important in the modeling of
consumptive uses and in valuing the agricultural sector dependent on those crops.
Various combinations of data sources and methodologies were used to obtain the best estimates
of crop distribution within each basin: interviews with local water users and administrators (such as
extension agency); producer reports (irrigation district data); stereo aerial photography, U.S. Department
of Agriculture (USDA) agencies (Service Center, Natural Resources Conservation Service [NRCS],
5-35-