Accurate delineations of irrigated acreage are needed for the development of water-use estimates and in determining water-budget calculations for the Basin and Range carbonate-rock aquifer system (BARCAS) study. ISatellite imagery from the Landsat Thematic Mapper and Enhanced Thematic Mapper platforms were used to delineate irrigated acreage on a field-by-field basis for the entire study area. Six hundred and forty-three fields were delineated. The water source, irrigation system, crop type, and field activity for 2005 were identified and verified through field reconnaissance.

Accurate delineations of irrigated acreage are needed for the development of water-use estimates and in determining water-budget calculations for the Basin and Range carbonate-rock aquifer system (BARCAS) study. ISatellite imagery from the Landsat Thematic Mapper and Enhanced Thematic Mapper platforms were used to delineate irrigated acreage on a field-by-field basis for the entire study area. Six hundred and forty-three fields were delineated. The water source, irrigation system, crop type, and field activity for 2005 were identified and verified through field reconnaissance.

Accurate delineations of irrigated acreage are critical in the development of water-use estimates and in determining an accurate water budget for the hydrographic basins of the BARCAS study area. Currently, irrigated acreage is estimated routinely for only a few basins in the study area and these acreages are calculated and reported by township range section, quarter, and quarter-quarter. Satellite imagery from the Landsat Thematic Mapper (TM) platform was used to delineate irrigated acreage for the BARCAS study area on a field by field basis. Six hundred and forty-three fields were delineated by interpreting satellite data. The water source, irrigation system, crop type, and field activity were identified and verified through field reconnaissance. These data were integrated into the geodatabase and analyzed to develop reasonably accurate estimates of irrigated acreage for the 2000, 2002, and 2005 growing seasons by hydrographic area and sub-area. Estimated average annual potential evapotranspiration and average annual precipitation were incorporated into the geodatabase as ancillary data. Irrigated acreage in 2005 totaled nearly 32,000 acres ranging from less than 200 acres in Butte, Cave, Jakes, Long, and Tippett Valleys to 9,200 acres in Snake Valley. Cave, Irrigated acreage increased about 20 percent from 2000 to 2005, with Snake and White River Valleys experiencing the greatest increases. The source for about 80 percent of irrigation water applied during drier years is ground water pumped from wells. About 80 percent of irrigation water applied in 2005 was through sprinkler systems, and about 20 percent was through flood systems. Fields planted in alfalfa accounted for about 88 percent of the irrigated acreage.

Accurate delineations of irrigated acreage are critical in the development of water-use estimates and in determining an accurate water budget for the hydrographic basins of the BARCAS study area. Currently, irrigated acreage is estimated routinely for only a few basins in the study area and these acreages are calculated and reported by township range section, quarter, and quarter-quarter. Satellite imagery from the Landsat Thematic Mapper (TM) platform was used to delineate irrigated acreage for the BARCAS study area on a field by field basis. Six hundred and forty-three fields were delineated by interpreting satellite data. The water source, irrigation system, crop type, and field activity were identified and verified through field reconnaissance. These data were integrated into the geodatabase and analyzed to develop reasonably accurate estimates of irrigated acreage for the 2000, 2002, and 2005 growing seasons by hydrographic area and sub-area. Estimated average annual potential evapotranspiration and average annual precipitation were incorporated into the geodatabase as ancillary data. Irrigated acreage in 2005 totaled nearly 32,000 acres ranging from less than 200 acres in Butte, Cave, Jakes, Long, and Tippett Valleys to 9,200 acres in Snake Valley. Cave, Irrigated acreage increased about 20 percent from 2000 to 2005, with Snake and White River Valleys experiencing the greatest increases. The source for about 80 percent of irrigation water applied during drier years is ground water pumped from wells. About 80 percent of irrigation water applied in 2005 was through sprinkler systems, and about 20 percent was through flood systems. Fields planted in alfalfa accounted for about 88 percent of the irrigated acreage.

Delineated irrigated acreage in 2005 was field verified from September 26 to 29 and November 1 to 3 , 2005. Fields were visited to confirm that irrigation had occurred in remotely delineated polygons. The irrigation method, crop type, and water source for each field also was inventoried. The location of each delineated field was checked using a handheld GPS. Digital photographs were taken of each field and the bearing and time of each photograph was documented.

Delineated irrigated acreage in 2005 was field verified from September 26 to 29 and November 1 to 3 , 2005. Fields were visited to confirm that irrigation had occurred in remotely delineated polygons. The irrigation method, crop type, and water source for each field also was inventoried. The location of each delineated field was checked using a handheld GPS. Digital photographs were taken of each field and the bearing and time of each photograph was documented.

This data set consists of sub delineations of the hydrographic area (HA) boundaries and polygons drawn at 1:1,000,000 scale for the Great Basin supplemented by information from HA drawn at 1:750,000 scale where necessary. See the process steps for more information.

This data set consists of sub delineations of the hydrographic area (HA) boundaries and polygons drawn at 1:1,000,000 scale for the Great Basin supplemented by information from HA drawn at 1:750,000 scale where necessary. See the process steps for more information.

These data represent potential areas of ground-water discharge for selected hydrographic areas in eastern Nevada and western Utah. The data are based on phreatophyte boundaries published by the U.S. Geological Survey (USGS) and on unpublished boundaries mapped by the Southern Nevada Water Authority (SNWA). Selected basins also were mapped by the USGS during an aerial field reconnaissance. The largest phreatophyte extent from all the sources was typically selected as the final boundary where a basin was covered by multiple boundaries. Selected basins were field verified and modified to reflect the ground condition during the summer of 2005. This data set also includes subbasin boundaries identified by Sweetkind and others (2007) (See Source_Information). The table below lists the boundary sources for each valley and whether the data were ground verified. > Valley Sources Field > verified ------------------------------------------------------------------------------------------ >Little Smoky Nichols, 2000; Harrill, 1988 Yes >Newark Nichols, 2000; Harrill, 1988 Yes >Long Nichols, 2000; Harrill, 1988; SNWA Yes >Jakes Nichols, 2000; SNWA Yes >Butte Nichols, 2000; Harrill, 1988; SNWA Yes >Steptoe Nichols, 2000; Harrill, 1988; SNWA No >Tippett Nichols, 2000 No >Spring Nichols, 2000; Harrill, 1988; SNWA Yes >Snake Harrill, 1988; SNWA; Aerial No >Lake Harrill, 1988; SNWA; Aerial Yes >Cave SNWA; Aerial No >White River Harrill, 1988; SNWA; Aerial Yes

This data set represents the extent of the Basin and Range carbonate-rock aquifers in the states of Idaho, Utah, Arizona, Nevada, and California.