Discussion
The water saved as a result of the biological control of Arundo donax along the Rio Grande
occurs between San Ignacio and Del Rio on the Mexico-Texas, U.S. border. Water flow for this
reach of the Rio Grande is controlled by the operation of Falcon and Amistad dams. The
reduction in Arundo suggests increased flow into the reservoirs. Since Falcon has more water
losses than Amistad, any water saved between the dams will allow more water to be held at
Amistad, thus improving the efficiency of the system (Rubinstein 2008).
The early involvement of economists in this project has provided opportunities for
participation during the total research project. This has been helpful in ensuring the appropriate
(e.g., type and required accuracy) data are collected to conduct the economic analyses.
The use of the biological control agents is anticipated to result in added water for use in
the Texas Lower Rio Grande Valley. With rapid population growth and shortfalls of water, this
will be beneficial to the region and help to maintain irrigated agriculture. A key piece of the
study relates to whether the benefits justify the expenditures of federal (social) resources. The
amount of water saved, and the value thereof, from the control of giant reed is still an estimate at
this date (i.e., February 2009).
The USDA-ARS is in the process of obtaining a permit for the release of one beneficial
insect and is in the process of receiving permission for the release of a second insect. Once
Arundo donax is controlled, more water will be available for South Texas. Given agriculture is
expected to be the beneficiary of the saved water, there will be added acres irrigated, which
means more production of commodities and hence, increased returns and increased gross
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