Good Neighbor Environmental Board

June 28, 2012

Shared US-Mexico 

Transboundary Water Resources

Principal Engineer Carlos Pena
 Texas A&M AgriLife Research, Texas Water Resources 

Institute: Ari Michelsen, Zhuping Sheng, Danielle Kalisek

 NM Water Resources Research Institute: 

Phil King, John Hawley, Sam Fernald, Bobby Creel

 AZ Water Resources Research Center: 

Sharon Megdal & Chris Scott

 USGS: Bill Alley, John Schefter; TX, NM, AZ Science 

Centers: Mike Darr, James Calgary, Rodger Ferriera, 

Doug McCda, Ann Ardis, John Bumgarner

 IBWC/CILA: Gilbert Anaya, Ramiro Lujan

Project Team
Background and Relevance

 Population growth along US-Mexico border is among 

the highest nationally. 

 Groundwater is the major water source for much of the USMX border region. Groundwater is used for all the drinking 

water in southern NM, all of Juarez, and more than half of the 

El Paso area. 

 There is inadequate information on the extent, quantity, 

quality and interaction of border aquifers. 

 Availability of ground water is a key economic & health 

issue in the U.S. – Mexico border region 

 Economic development is/will be restricted by 

lack of adequate, reliable, safe water
 How extensive are the aquifers?

 Which directions are the aquifers flowing?

 How deep are the aquifers?

 What is the quality of the aquifers at various 

depths?

 How fast are they declining in supply and quality?

 What is the long-term availability?

 What is the relationship between surface supplies 

and aquifer recharge/depletion (conjunctive use)?

Information about border aquifers is 

inadequate - many questions remain:
 Public Law 109-448 enacted December 2006

 Authorized $50 million over 10 years, 2006-2015

 Develop scientific knowledge of US-MX bi-national 

aquifers in Texas, New Mexico and Arizona (not CA) 

 Joint program of USGS and the three Water

Resources Research Institutes

 Specified four priority aquifers, Mesilla Bolson (NM, 

TX, MX), Hueco Bolson (NM, TX MX) and San 

Pedro and Santa Cruz Aquifers (AZ, MX) 

 Additional aquifers may be added

US-MX Transboundary Aquifer Assessment Act
 WRRI’s to work with USGS, stakeholders, agencies 

and MX to coordinate, develop and implement plans 

of work (using IBWC framework)

 $2 million funded to date 

 Funding split 6 ways, 3 USGS State Offices and the 3 

WRRIs in TX, NM and AZ

 WRRI portion shared with MX and State entities for

data collection in Mexico, at a minimum of 1:1 cost 

share

US-MX Transboundary Aquifer Assessment Act
 Nothing in the TAA Act or Program will affect 

jurisdictions or existing water rights, laws, compacts 

or treaties 

 Major State and bi-national concern

 Difference in governance US States/MX Federal

 Scientific knowledge period. Not to be used to 

control, coerce, or develop/change treaties 

US-MX Transboundary Aquifer Assessment Act
 Develop high-quality, comprehensive, bi-national

groundwater quantity and quality databases

 Assess the extent, availability, quality and use of border aquifers

 Analyze trends in groundwater quality, including salinity, 

nutrients, toxics, and pathogens

 Develop and improve groundwater flow models for bi-national 

aquifers to facilitate regional water assessment and planning 

 Assess the movement and use of conjunctive surface-ground water

 Develop updated watershed delineations 

 Apply the new data and models to evaluate strategies to enhance 

supplies and protect water quality

US-MX TAAP Objectives
U.S.-MexicoTransboundary Aquifer 

Assessment Program

Designated priority transboundary aquifers
Transboundary Aquifers in NM-TX
Arizona – Sonora 

Santa Cruz and San Pedro Shared 

Aquifers

Santa Cruz River valley at 

Rio Rico, Arizona
 Joint USGS-WRRI, US stakeholder and public meetings 

have been held identifying and prioritizing needs

 Coordinated USGS-WRRI US plans of work have been 

developed and reviewed by stakeholders

 MX scope of work developed for TX and NM research in 

consultation with US-MX (IBWC).

 MX-AZ scope of work developed through IBWC

 Interim report to Congress in preparation

TAA Program Activities
Scientific Studies in the Mesilla Basin 

Aquifer System of NM, TX and Chihuahua

 An updated Lower Rio Grande hydrologic model of the 

Rincon Valley and Mesilla Basin is being integrated with 

an agricultural water use model to assess groundwater and 

surface water interaction and conjunctive uses 

 Geochemical samples and analyses are being performed 

 Existing hydrogeologic framework models will be 

evaluated for an expanded scope extending into Mexico

 Study completed by Mexico “Hydrogeological Activities 

in the Conejos Medanos-Mesilla Basin Aquifer, 

Chihuahua Phase I”, May 2011
Scientific Studies in the Mesilla Basin 

Aquifer System of NM, TX and 

Chihuahua

 Data gaps and additional information needed for US, 

MX and bi-national hydrogeologic model development 

are being identified

 Coordinated US-MX work plans for data collection and 

models have been developed

 US and bi-national groundwater models will be 

developed and refined using existing and new data 
Scientific Studies in the Mesilla Basin 

Aquifer System of NM, TX and Chihuahua

 A comprehensive review of US literature and identification and 

initial review of existing models has been conducted. The 

literature has been entered into a digital database allowing 

bibliographic searches and sharing

 Existing geological, hydrogeologic monitoring data, ancillary 

databases, and GIS information has been compiled

 An overview analysis of the Mesilla Basin Aquifer hydrogeologic 

framework and related aspects of groundwater flow and chemistry 

is under development 

 The hydraulic connection between Mesilla Basin and adjacent 

basins will be characterized using existing and new data
 Santa Cruz and San Pedro aquifer scientific and other 

published materials will be compiled in a searchable, 

online, bilingual data base

 Work on contaminant transport modeling and 

development of hydrogeological framework models in the 

Santa Cruz Valley has been initiated

 Development of recharge/runoff monitoring and modeling 

of the San Pedro has been initiated 

 A bi-national report is being developed to compile data in 

the Santa Cruz and San Pedro Aquifers into one document

AZ –SONORA TAA Program Activities
Joint Cooperative Framework

 The objective of the joint cooperative process for 

groundwater research is to improve the knowledge 

base of transboundary aquifers.

 Assure concurrence of the US and MX for 

binational aquifer assessment activities

 Establish and coordinate binational technical 

advisory committees for each aquifer

 Serve as an official repository for binational 

studies developed

17
Distribution between Mexico and the 

U.S. of the waters originating in the 

Upper Rio Grande watershed.

U.S. to deliver 60,000 acre-feet per year 

to Mexico at the headworks of the 

Acequia Madre Canal 

Proportional reduction in deliveries in 

case of extraordinary drought

Project water stored in Elephant Butte 

and Caballo Dams – New Mexico

American Dam

United 

States

Mexico

American 

Dam

American 

Canal

Convention of 1906
International Dam

Mexico’s Deliveries

US Deliveries

3 Primary Entities served with Project 

Water from Elephant Butte and 

Caballo reservoirs

• Elephant Butte Irrigation District

• El Paso County Water 

Improvement District No. 1

• Mexico

Poor contingency planning in winter of 

2011 led to a delivery timing conflict 

in 2012.
• Initiate early contingency planning with all 

three irrigation entities (Fall of 2012)

• Need better understanding of how surface 

water in channel interacts with aquifer.

• Need better understanding of how 

groundwater pumping impacts channel 

conveyance efficiencies.

• Federal study - (USIBWC/Reclamation) with 

input from 3 irrigation entities to analyze 

surface/groundwater interactions of system 

and propose operational strategies to better 

manage precious resource.

Lesson’s Learned from 2012 Deliveries 

under the 1906 Convention