United States-Mexico Transboundary Aquifer Assessment Act

United States-Mexico Transboundary Aquifer Assessment Act - (Sec. 3) Defines specified terms.

(Sec. 4) Establishes a United States-Mexico transboundary aquifer assessment program to characterize, map, and model groundwater resources along the border. Describes as the program's objectives to: (1) develop an integrated approach to assess priority transboundary aquifers, including creating or enhancing a geographic information system database for each priority aquifer; (2) consider expanding existing agreements between the U.S. Geological Survey, the participating states (Arizona, New Mexico, and Texas), the water resources research institutes, and appropriate U.S. and Mexican authorities to conduct joint scientific investigations and archive and share relevant data; and (3) produce scientific products for each priority aquifer to provide water managers and natural resource agencies with necessary information.

Directs the Secretary of the Interior to designate as priority transboundary aquifers the: (1) Hueco Bolson and Mesilla aquifers; (2) Santa Cruz River Valley aquifers; and (3) San Pedro aquifers.

Authorizes the Secretary to: (1) designate additional aquifers which underlie Texas or New Mexico; and (2) provide grants or enter into agreements with water resources research institutes and participating state entities to carry out the program.

Directs the Secretary to develop partnerships with relevant organizations in Mexico to carry out the program.

(Sec. 5) Directs the Secretary to: (1) coordinate activities with water resource agencies in the participating states, affected Indian tribes, and other entities conducting monitoring and metering activities, including the International Boundary and Water Commission; and (2) work with participating state water resource agencies, water resources research institutes, and other relevant entities to develop a study plan, timeline, and cost estimate for each priority transboundary aquifer to be studied under the program.

Prohibits the Secretary from initiating any field studies before consulting and coordinating with the participating state water resource agency with jurisdiction over the aquifer.

(Sec. 6) Prohibits anything in this Act from affecting: (1) the jurisdiction or responsibility of a participating state with respect to managing its surface or groundwater resources; (2) the water rights of any person or entity using water from a transboundary aquifer; or (3) state water law, or an interstate compact or international treaty governing water.

Prohibits anything in this Act from delaying or altering the implementation or operation of any works constructed, modified, acquired, or used within the territorial limits of the United States relating to the waters governed by the Treaty Between the United States and Mexico Regarding Utilization of Waters of the Colorado and Tijuana Rivers and of the Rio Grande, Treaty Series 994.

(Sec. 7) Sets forth program reporting requirements.

(Sec. 8) Authorizes FY2006-FY2016 appropriations. Obligates 50% of such funds for entities in the participating states (including Sandia National Laboratories, state agencies, universities, the Tri-Regional Planning Group, and other relevant organizations) and Mexico to conduct program activities, including the binational collection and exchange of scientific data.

(Sec. 9) Terminates the Secretary's authority under this Act 10 years after its enactment.