The Convergence of Water Rights, Structural Change, Technology, and Hydrology: A Case Study of New Mexico's Lower Rio Grande

Irrigated areas throughout the western United States are undergoing water rights adjudication. At the same time, agriculture is undergoing significant structural change, including increasing numbers of smaller, lifestyle-based farms. Today's remote-sensing technology makes it possible to accurately estimate evapotranspiration on individual fields and aggregate this information to basin-wide crop consumptive use. The difference between actual and theoretical consumptive use creates the potential for hydrologic deficits if the theoretical levels are adjudicated (e.g., established as rights) and then consumptively used. This article examines the implications of theoretical versus actual consumptive use and includes a case study of New Mexico's Lower Rio Grande region to illustrate the convergence of water rights adjudication and structural changes in agriculture. It also highlights recently introduced technologies for estimating consumptive use and explores the numerous hydrologic risks of adjudication based on theoretical, rather than actual or historic, consumptive use.