The State of the AquifersThe Transboundary Santa Cruz and San Pedro
River basinsPrescott Vandervoet
Christopher ScottSharon Megdal
The University of Arizona
2010 AHS Annual Symposium: "Dryland Hydrology: Global Challenges, Local Solutions”
Co-hosted with the International Association of Hydrogeologists
9/2/10 1AHS Annual Symposium
Overview• What is the status of
water resources and management of the transboundary Santa Cruz and San Pedro aquifers?
• What factors determine the status?– Natural Environment– Use (pumping)– Governance– Water quality
9/2/10 2AHS Annual Symposium
VariabilityMonthly Mean Discharge (cfs)
9/2/10 AHS Annual Symposium 3
OctoberJanuary
AprilJuly
0
100
200
300
400
500
600
700
800
OctoberJanuary
AprilJuly
0100200300400500600700800900
1000
Nogales Gage, USGS
Palominas Gage, USGS
Population Drivers of Future Demand
Continued growth (projections from 2005)
9/2/10 4AHS Annual Symposium
0
20000
40000
60000
80000
100000
120000
140000
1950 1960 1970 1980 1990 2000
Cochise CountySanta Cruz CountySierra Vista
Nogales, AZ
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
180,000
200,000
2010 2012 2014 2016 2018 2020 2022 2024 2026 2028 2030
Cochise CountySanta Cruz CountySierra Vista
Nogales
US Census Bureau, 2010 AZ Dept. of Commerce, 2010
0
50000
100000
150000
200000
250000
300000
350000
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Nogales, Sonora
Santa Cruz, Sonora
Cananea, Sonora
Naco, Sonora
Municipio-level population, CONAPO, 2010
9/2/10 AHS Annual Symposium 5
Water Use
9/2/10 AHS Annual Symposium 6
0
5000
10000
15000
20000
25000
1985 1990 1995 2000 2005
Demand and changing sectoral water use
Af/yr in Santa Cruz AMA, ADWR
0
5000
10000
15000
20000
25000
2000 2005 2010 2020 2030
Municipal
Industrial
Agricultural
Af/yr in Sierra Vista subwatershed, ADWR
9/2/10 AHS Annual Symposium 7
Drivers of future scenarios
9/2/10 AHS Annual Symposium 8
Demand and changing sectoral water use
Scott et al., in review
Water use in Santa Cruz basin, Mexico (not including Nogales Wash)
Groundwater BalanceRecharge and pumping
Acre-Feet Million Cubic Meters
Acre-Feet Million Cubic Meters
Supply 39,600 – 142,900 48.8 - 176 18,000 22.2
Demand 21,105 26.0 16,920 20.9
Supply ??? ??? 33,200 41.0
Demand 23300 28.7 23,595 29.1
9/2/10 AHS Annual Symposium 9
Sources: USPP 2007 321 Report, ADWR , Conagua Estudios de Disponibilidad
US
Mex
Santa Cruz San Pedro
21105 AF25.0 MCM
309 AF0.38 MCM
23300 AF28.7 MCM
23595 AF29.1 MCM
16920 AF20.9 MCM
Santa Cruz, Arizona
Nogales Wash, Sonora
Santa Cruz, Sonora
San Pedro, Sonora
San Pedro, Arizona
Regional use/availability breakdown
9/2/10 AHS Annual Symposium 10
Sources: ADWR, CONAGUA, USPP
water withdrawn by basin/nation per year
Santa Cruz BasinSan Pedro Basin
Groundwater Balance and Management
• Upper Santa Cruz– SCAMA tasked with
maintaining sustainable yield– Nogales, Sonora has at times
been forced to purchase water from Nogales, AZ
• Upper San Pedro– In 2004 local actors charged
with restoring and maintaining sustainable yield in Arizona
– Drawdowns noted of up to 3 meters between 1995-2000 along river channel in Mexico
9/2/10 11AHS Annual Symposium
Management
9/2/10 12AHS Annual Symposium
• Important to recognize differing nature of water management
• How do unique management regimes interact across the border within shared basins?
Differing management
regimes
9/2/10 AHS Annual Symposium 13
Source: Milman and Scott, 2010
Description of Management Responsibilities for Agencies within Basins
Arizona• Arizona Department of Water
Resources– Administers and enforces State
groundwater code• US Geological Survey
– collects information needed to understand water resources.
• US Bureau of Land Management– manages the nation's public lands and
resources…. balancing recreational, commercial, scientific and cultural interests and strives for long-term protection of renewable and nonrenewable resources.
• Utilities
Sonora• National Water Commission
– Administer and preserve national waters to achieve their sustainable use.
• State Water Commission– Promote the coordinated
development and efficiency of water resources in Sonora.
• Municipal Utilities– Provisioning and supply to urban
users
9/2/10 AHS Annual Symposium 14
Binational Cooperation and Initiatives• Arizona Mexico
Commission– State-level work group since
1959 with 13 binational committees (including water)
• Border Environmental Cooperation Commission– Preserve, Protect, Enhance
human health and environment along border
• Transboundary Aquifer Assessment Program
• Transboundary Aquifer Assessment Program (TAAP)– U.S. Federal Law 109-448– Secretary of Interior to
systematically assess priority transboundary aquifers
– Santa Cruz and San Pedro identified on Arizona/Sonora border
– Approval for appropriation of 50 million dollars over 10-year period
– Collaborative project between USGS and Water Resource Centers within Texas, New Mexico, and Arizona
9/2/10 AHS Annual Symposium 15
9/2/10 AHS Annual Symposium 16
Transboundary Aquifer Assessment Program
• Goals and Achievements– Formation of binational work
group to prioritize assessment activities
– Engagement of stakeholders throughout basins and administrative areas.
– Interaction at regional and binationally-focused meetings regarding groundwater issues.
Transboundary Aquifer Assessment Program
• Goals and Achievements– Design of work plans for
assessment of shared groundwater resource
– Beginning stages of binationally coordinated aquifer studies in Mexico
– Collaborators include: ADWR, CONAGUA, CEA-Sonora, USPP, FOSCR, among others.
9/2/10 AHS Annual Symposium 17
Contacts and WebpagePrescott [email protected] [email protected]
9/2/10 AHS Annual Symposium 18
Sharon [email protected] [email protected]
www.cals.arizona.edu/azwater/taap
