The data set consists of monthly sums of 30-minute evapotranspiration measurements made at the USGS Starkey pasture climate station beginning May 1, 2003 and ending April 30, 2016. Annual evapotranspiration rates corrected to a near-surface energy-budget for the 12 calendar years of record at this site (2004-2015) varied from 718 millimeters (2007) to 903 millimeters (2010). The eddy-covariance method was used, with high-frequency sensors installed above the pasture to measure sensible and latent heat fluxes. Ancillary meteorological data are also included in the data set: rainfall and ground-water levels. Data were collected at 30-minute resolution, with evapotranspiration corrected to the near-surface energy-budget at that timescale. Related data sets are presented at 30-minute and daily time intervals. The study was conducted at a nearly flat, non-irrigated site (Latitude 28 13 31 North Longitude 82 33 33 West in degrees minutes seconds, NAD 1927, Section 13, Township 26S, Range 17E) within the Anclote River Ranch property owned by the Southwest Florida Water Management District in Pasco County, Florida. The site was also within J.B. Starkey Wilderness Park. Instrumentation was installed in April 2003. The dominant (about 80 percent of surface coverage) plant cover at the study site is bahiagrass (Paspalum notatum) that varies from a lush green during the summer to a drab brown during the winter. The bahiagrass is ungrazed and grass height can reach 0.5 meter. During the study, the pasture was mowed periodically to 0.2 meters. Vegetation tables provided with the data release list when mowing occurred. Maximum grass rooting depth at the site is about 0.5 meters. Other plants at the study site, intermixed with the bahiagrass and occurring as distinct patches, include bushy broom grass (Andropogon glomeratus), rush (Juncus spp.), dog fennel (Eupatorium capillifolium), flat-topped goldenrod (Euthamia minor), and groundsel tree (Baccharis halimifolia). Forested wetlands are present on the margins of Sandy Branch, a tributary to the Anclote River southwest of the site, and a small cypress dome (40 meter diameter) is located east of the site. The effects of these forested areas are assumed to be negligible, as the pasture area extends 175 meters away from the site in all directions and satisfies upwind fetch requirements for the height of the eddy covariance sensors (more than 100 times the final height of 1.5 meters). The soils at the site are Pomona fine sands with less than 5 percent organic content. For the 13 years of record at this site, the water table was always within 2 meters of land surface.