Climate Change Impacts on Hydropower in the Rio Grande River Basin
KEY MESSAGE: Climate change has the potential to reduce hydropower production in the Rio Grande
Basin through decreases in streamflow, increases in temperature, and increases in evaporation rates. Policy makers need to act quickly and effectively to implement the development of sustainable energy alternatives, encourage conservation and efficiency, and construct hydropower plants at existing dam sites.
T
he Rio Grande is an essential freshwater
source for over 13 million people living in
northern Mexico and the southwestern
U.S. (USCB 2013, CONAPO 2013). At
1,896 mi (3,051 km) long, the Rio Grande is the
fifth longest river in North America and the twentieth longest river in the world. Starting at the headwaters in the San Juan Mountains of southern Colorado, the Rio Grande flows southward through New
Mexico, Texas, and Mexico where it empties into
the Gulf of Mexico. The Rio Grande flows 1,255 mi
(2,019 km) along the U.S. Mexico border, splitting
the river’s 182,000 mi2 (471,000 km2) drainage basin nearly equally between the two countries (IBWC
2014).
Hydropower in the Rio Grande River Basin
There are 21 major dams and diversion located
along the Rio Grande (Figure 1), eight of which are Figure 1. Dams and diversions located on the Rio Grande. Source:
used for hydropower generation (Kao et al. 2014).
Bullard & Wells 1992.
Currently, the Rio Grande Basin has 159 megawatts
(MW) of hydropower capacity and generates 312,000 meg- Texas and the State of Coahuila, Mexico, is the next largest
awatt hours (MWh) of electricity annually (Kao et al.
hydropower dam on the Rio Grande (TWDB 2014a). It
2014), which is enough to support approximately 29,000
contains two power plants, one generating power for each
U.S. households (USEIA 2012).
country, and is managed by the International Boundary and
The largest hydropower dam by size on the Rio Grande Water Commission. Combined, the power plants generate
is the Elephant Butte Dam, located in Truth or Consequenc- approximately 161,000 MWh annually (IBWC 1990). The
es, New Mexico. Completed in 1912, the Elephant Butte
storage capacity of the Amistad International Reservoir is
Dam is a major component of the Rio Grande Project, a
3.3 million acre-feet (4.1 km3) (TWDB 2014a).
series of dams, drainage channels, and canals on the Upper
Another major hydropower plant located on the Rio
Rio focused on irrigation, hydroelectric, flood control and
Grande is the Falcon Dam, which is located between Starr
interbasin water transfer (USBR 2009). Collecting water
County, Texas and Nueva Ciudad Guerrero in Mexico.
from a catchment of 28,900 mi2 (74,900 km2), which is
Completed in 1945, the Falcon Dam has an installed capacabout 16 percent of the total drainage basin, the Elephant
ity of 63 MW (IBWC 1990). The Falcon International ResButte reservoir is capable of storing over 2 million acre-feet ervoir has a storage capacity of 2.6 maf (TWDB 2014b).
(2.5 km3) of water (USBR 2009). The Elephant Butte hyWhile relatively little hydropower is currently generatdropower plant has a capacity of 27.95 MW and is able to
ed in the Rio Grande Basin, there is great potential for ingenerate 56,003 MWh of electricity annually (USBR 2009). creased development. It is estimated that the total undevelThe electricity generated at Elephant Butte is distributed
oped hydropower capacity of the Rio Grande is 1.64 gigathrough an electrical grid totaling 490 mi (788.6 km) of 115 watts (GW), which is ten times more than is currently inkilovolt transmissions lines and 11 substations (USBR
stalled (Kao et al. 2014). Such capacity could generate 9.31
2009).
terawatt hours (TWh) of electricity per year, nearly 30
The Amistad Dam, which straddles Val Verde County, times current generation rates (Kao et al. 2014). These fig-
ures take into account only U.S. streams, therefore the undeveloped hydropower in the entire
basin, including Mexico, could be greater.
Hydropower development has not been the
main priority in the Rio Grande Basin. The Rio
Grande’s semi-arid climate has created a region
focused primarily on water resources for agriculture and municipal. The majority of the water
used in the Rio Grande is used for agriculture
and municipal purposes, supplying more than 6
million people with drinking water and 2 million acres (800,000 hectares) of land with irrigation water (IBWC 2014). Agriculture and urban
landscaping will require more water with the
anticipated increase in temperature (Llewellyn
& Vaddey 2013). Growing populations in U.S.
Figure 2. Decrease in the flow into the Elephant Butte Reservoir under
and Mexican urban centers will increase munici- baseline conditions and under full delivery with management strategies
pal demands. To reconcile increased demand
utilized to meet allocation requirements. Source: Llewellyn & Vaddey
with decreased supply, there will likely be a
2013.
shift from using the Rio Grande’s surface water
to non-renewable groundwater. The new dependence on
nitude, timing, and spatial distribution of stream flow, due
groundwater will lead to over-extraction, resulting in lower to the fact the Rio is mostly snow fed (Llewellyn & Vaddey
water availability in the Rio Grande due to the lack of base 2013). Mean annual runoff is predicted to decrease by 7.3flow from surrounding aquifers and tributaries (Llewellyn
14.4 percent by 2050 (USBR 2011), which will decrease
& Vaddey 2013).
inflows into reservoirs (Figure 2). Peak flow from the
river’s headwaters in Colorado is predicted to arrive in May
Climate Change in the Rio Grande River Basin
instead of June, and overall flow will decrease between
June and September (Llewellyn & Vaddey 2013). Some
Climate change is projected to decrease water availabil- studies estimate that climate change could reduce Rio
ity, change peak flow periods, increase extreme weather
Grande flows by 4-14 percent by 2030 and 8-28 percent by
events, alter precipitation patterns, and increase temperature 2080 (Hurd & Coonrod 2008).This combination of changes
in the Rio Grande Basin. During the period 1971-2011, the will lead to an overall decrease in water availability.
average temperature in the Upper Rio Grande Basin increased roughly 0.7° F (0.4° C) per decade, approximately
Climate Change Impacts on the Energy Sector
double the global rate of temperature rise during this time
(Llewellyn & Vaddey 2013). Climate studies utilizing nuLower streamflow will impact the productivity of hymerous general circulation models and future atmospheric
dropower dams in the Rio Grande basin. Overall, lower
carbon dioxide scenarios predict there will be a 4.0-6.0° F
streamflows will lead to lower reservoir levels (Llewellyn
(2.2-3.3° C) increase in the upper basin by the end of the
& Vaddey 2013), resulting in decreased in hydropower
21st century (Llewellyn & Vaddey 2013). Furthermore, pre- generation (Figure 3). Decreases in water level have alcipitation is forecast to decrease by 2.3-2.5 percent by
ready been observed in reservoirs along the Rio Grande.
2050, and variability in the magnitude and timing of precip- During the main irrigation season of 2012, reservoir levels
itation is predicted to increase (USBR 2011).
were observed dropping by 2.5 feet per day (0.76 meters
An increase in temperature and changes in the precipiper day) (Guido 2012). In the Upper Rio Grande basin there
tation patterns may have a variety of effects on streamflow is 15 MW of hydropower capacity available, but this is prein the Rio Grande Basin. Currently, water lost through
dicted to decrease by nearly 50 percent by the end of the
evaporation in this semi-arid to arid climate exceeds the
21st century (Llewellyn & Vaddey 2013). Most of this dewater gained by precipitation, a disparity that will only
crease will likely occur between May and September, the
grow larger as evaporation rates increase and precipitation
same months in which streamflow is predicted to decrease.
rates decrease (Patina et al. 2005). Additionally, predicted
Potential increases in evaporation rates from open reserearlier dates of snowmelt will lead to variability in the mag- voirs may also impact hydropower generation (Figure 4),
yet the volume of water lost
Grande’s location in a arid
could decrease over time
to semi-arid region makes
because less water surface
solar energy a viable alteris exposed to air as resernative. In Culberson Counvoir levels decrease.
ty, Texas, located northeast
Decreases in hydropowof the Rio Grande, there are
er generation are predicted
two wind farms utilizing
to coincide with increasing
147 turbines with a 68 MW
energy demand as populacapacity, enough to power
tions grow in the Rio
15,650 average Texas
Grande Basin. Over the last
homes (American Wind En40 years, the population of
ergy Association 2008). Polthe border communities has
icies should focus on the
doubled every 20 years, and
promotion of alternative
it is predicted to double
energy sources which do not
again by 2030 (Schmandt
rely on the availability of
2002). Region M of the Rio
water in the Rio Grande or
Figure
3.
The
predicted
hydropower
generation
in
the
Upper
Grande, which includes
the burning of fossil fuels.
Rio Grande basin. Shows three major hydropower dams.
eight counties of Texas, is
In order to maintain the
expected to grow from 1.7 Source: Llewellyn & Vaddey 2013.
current hydroelectric promillion in 2010 to 4 million
duction in the Rio Grande
in 2060, increasing water demand by 35 percent (RGRWA Basin, polices which protect streamflow and increase water
2010). Current hydropower capacity in the basin will be
levels in reservoirs must be implemented. Overall, conserunable to address the basin’s growing energy needs.
vation and efficiency in agricultural and municipal water
use will be needed to continue hydropower production. As
stated before, agriculture and municipalities use the majoriPolicy Implications
ty of water in the Rio Grande basin. Programs promoting
The Rio Grande is managed by the International
efficient irrigation techniques and water efficient crops will
Boundary and Water Commission (IBWC), which is relead to a decrease in water use by farmers. Additionally,
sponsible for water distribution, conservation, and implewater-sharing programs, in which farmers sell water rights
mentation of treaties and agreements. The Convention of
to municipalities, will lead to an reduction in water loss due
1906 allocates the waters from El Paso to Fort Quitman
to the fact that crops will not be grown in high evaporation
along 89 mi (143 km) of the international border. The Eleareas. Aggressive conservation and efficiency will be needphant Butte Dam, funded by the U.S., was constructed to
ed to increase streamflow and continue the production of
meet the allocation of 60,000 acre-feet of water to Mexico
hydropower.
annually (Umoff 2008). The Water Treaty of 1944 adThe construction of more hydropower dams has been
dressed the utilization of the waters in the Colorado and the proposed in order to increase the energy production in the
Rio Grande from Fort Quitman, Texas to the Gulf of Mexi- Rio Grande since there is a high amount of potential hydroco (Umoff 2008). The Treaty of 1944 states that hydroelec- power. However, streams located in national parks and the
tric dams be built at international storage dams specified in presence of critical habitats and species make the constructhe Treaty, funded by the U.S. and Mexico, and operated
tion of hydropower dams a difficult task. There are 79 naand maintained by the Section engineer of each country.
tive species in the region, 11 of which are protected under
Climate change will impact the ability of the U.S. to deliver the Endangered Species Act and 14 of which are listed unMexico’s allotment of water, especially as the level in the
der the International Union for Conservation of Nature
Elephant Butte Reservoir decreases.
(Kao et al. 2014). Seventy-two percent of stream reaches
To address the energy deficit created by increasing dewith potential for development of hydropower have one to
mand and decreasing hydropower capacity, policymakers
two fish species falling under the ESA (Kao et al. 2014).
must support the development of sustainable energy alterConstructing new hydropower dams along the Rio Grande
natives. Overall, there is a strong potential for alternative
without harming sensitive habitats seems unlikely. If new
energy sources, wind, solar, and geothermal in the basin
hydropower plants are planned, they should be constructed
(American Wind Energy Association 2008). The Rio
at existing dam sites along the Rio Grande, instead of at
new locations. Policies which only allow the construction
of hydropower plants at existing dams may decrease the
risk of harming endangered species further.
In conclusion, climate change is predicted to have negative impacts on hydropower in the Rio Grande Basin. With
predicted increases in temperature, decreases in precipitation, and increases in evaporation rates, streamflows and
reservoir levels are anticipated to decrease in the basin, reducing hydropower production. Policies must focus on the
efficiency of water use, promote water conservation, investigate the potential alternative energy sources, and encourage construction of hydropower plants at existing dams.
Figure 4. Open-water evaporation rates at the Elephant Butte
Reservoir. Source: Llewellyn & Vaddey 2013.
-Authored by Victoria Lubner; Edited by Will Kort & Aaron Thiel; Supervised by Dr. Jenny Kehl
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