Arundo donax, or giant reed, is a large, bamboo-like plant that is native to Spain and has invaded several thousand acres of the Rio Grande riparian zone in Texas and Mexico. The plant grows to over 26 feet tall, and consumes large quantities of water, estimated as an amount equivalent to about 11% of irrigation water diverted by Valley irrigation districts (i.e., some estimates are more than 5.5 acre-feet per acre). With concern of increased water demands in the Texas Lower Rio Grande Valley region, the United States Department of Agriculture, Agricultural Research Service (USDA-ARS) is investigating four herbivorous insects as potential biological control agents for Arundo donax to facilitate increased water supply. This study examines selected economic implications for agricultural water users in the United States of applying these biological control agents along the Rio Grande. The research includes (a) estimating the value of the water saved due to the reduction of Arundo donax, (b) a benefit-cost analyses, (c) regional economic impact analyses, and (d) an estimate of the per-unit cost of water saved over a 50-year planning horizon (2009 through 2058). The model ArundoEcon is used to perform a baseline deterministic analyses using low- and high-value irrigated composite acre values. That is, the saved water is initially valued based on being applied to agriculture as irrigation. Since the actual crop mix irrigated with the saved water is unknown, a range is provided by assuming all irrigated crops are low-value, and then again by including both low-value and high-value irrigated crops.