This dataset contains the irrigated lands mapped for the Powder/Tongue River Basin Plan. All man induced irrigation or subirrigation was delineated. Natural subirrigated fields were not delineated unless some benefit was being received from a man made system. Irrigated lands were divided into the following categories based on visual interpretations of the quality of the irrigation, types of crops supported, and the type and condition of the irrigation delivery systems and on-farm systems used to serve these lands: A - Full service irrigation (typically receives a full water supply); B - Partial service irrigation (typically receives a reduced water supply due to limited water availability or the inability to provide complete field coverage); C - Man induced subirrigation (beneficial use resulting from incidental irrigation such as ditch seepage to areas below a canal); E - Idle irrigation (lands not currently receiving water, typically due to nonfunctional delivery facilities); S - Spreader dike irrigation (dikes constructed across ephemeral streams to spread infrequent flows over the land to increase beneficial use); H - Minor beneficial use (lands that receive some beneficial use on occasion such as lands served by "kick-out" ditches on ephemeral streams); AD, BD, and ED - A, B, or E lands that have undergone or are currently undergoing residential development.
