This data release provides a monthly irrigation water use reanalysis for the period 2000-20 for all U.S. Geological Survey (USGS) Watershed Boundary Dataset of Subwatersheds (Hydrologic Unit Code 12 [HUC12]) in the conterminous United States (CONUS). Results include reference evapotranspiration (ETo), actual evapotranspiration (ETa), irrigated areas, consumptive use, and effective precipitation for each HUC12. ETo and ETa were estimated using the operational Simplified Surface Energy Balance (SSEBop, Senay and others, 2013; Senay and others, 2020) model executed in the OpenET (Melton and others, 2021) web-based application implemented in Google Earth Engine. Results provided by OpenET/SSEBop were summarized to hydrologic response units (HRUs) in the National Hydrologic Model (NHM; Regan and others, 2019) to estimate consumptive use and effective precipitation on irrigated lands. Irrigated lands for the CONUS were provided by the Landsat-based Irrigation Dataset (LANID; Xie and others, 2019) for each year of the reanalysis period. Consumptive use estimates provided by the NHM were disaggregated to HUC12s using area weighted intersections with HRUs and the relative proportion of irrigated lands in each intersected area. The Landsat-based Irrigation Dataset (LANID) uses a random-forest machine-learning model with greenness and vegetative indices, climate data, and crop masks to identify irrigated crops (Xie and others, 2021, Xie and Lark, 2021). Separate western US and eastern US methods are used to train and validate the model. Annual LANID maps for 2018 -20 were created using the same techniques in Xie and others, 2021, and Xie and Lark, 2021.

Annual 30-m resolution irrigation maps, derivative products, and ground reference locations for the United States, 1997-2017, including:

(1) lanidYYYY (binary): Annual irrigation layer for the year YYYY (ranging from 1997 to 2017), e.g., lanid2017 is the irrigation map for the year 2017.

(2) irrFreq (1-21): The number of years irrigated during 1997-2017.

(3) irrFreqPasture_West: irrFreq of pasture/hay for the western CONUS.

(4) maxIrrExt (binary): Croplands that have been irrigated at least once during 1997-2017.

(5) irrFreqChange (1-21): The difference of number of years irrigated between 1998-2007 and that of between 2008-2017 (i.e., irrFreq_2008-2017 - irrFreq_1998-2007).

(6) irrAreaGain (-1684-2333): LANID-derived irrigation gain (in hectare) from 1998-2007 to 2008-2017 at the 6km×6km scale.

(7) formerIrr (binary): Not irrigated anytime in 2015-2017, but irrigated at least 3 times prior.

(8) irrWholePeriod (binary): Irrigated at least once for both 1997-1999 and 2015-2017.

(9) intermittentIrr (binary): Irrigated at least once for both 1997-1999 and 2015-2017, and irrigation frequency ≤ 18.

(10) irrSamples_eastCONUS: Sample locations of center pivot fields in the eastern CONUS (4976 sample locations).

(11) rainfedSamples_eastCONUS: Sample locations of stable rainfed fields in the eastern CONUS (4978 sample locations).

For technical details that used to create the dataset, please refer to https://doi.org/10.1016/j.rse.2021.112445; Data description details are available via https://essd.copernicus.org/preprints/essd-2021-207/.