Initial estimates begin with comparison of the U.S. Department of Agriculture – Farm Service Agency (FSA) records of irrigated crop acres to the previous five-year average of irrigated acres. Total water use is estimated utilizing available weather data, crop evapotranspiration rates, county averaged irrigation application efficiencies, and historical estimates of irrigation water use. Surface water irrigation diversions data are obtained from the Texas Commission on Environmental Quality (TCEQ) and their Watermasters. Total water use estimates and irrigated acres by county are sent to the groundwater conservation districts in the state for review and revision. Many groundwater conservation districts utilize metered and/or producer reported irrigation use data, and some conduct local surveys to improve their ability to assist TWDB in accurately depicting groundwater pumping in their counties of jurisdiction.
Irrigation is currently the largest water use demand sector in Texas – a trend that is projected to continue well into the future until it is surpassed by municipal demands in 2060. Irrigation in Texas is primarily from groundwater, and that water is the private property of the landowner. Metering, reporting, regulation, and management of the beneficial use of groundwater in Texas is left to the local jurisdiction of the groundwater conservation districts. This underlies the need for continued cooperation with local entities and for improved methodologies to accurately estimate irrigation water use in the state.
