U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2009-3014

June 2009

USGS Capabilities to Study the Impacts of Drought and 

Climate Change in the Southeastern United States

Printed on recycled paper

The Southeastern United States 

embodies a treasury of natural resources 

from ancient mountains to the Coastal 

Plain. A “Region of Rivers,” the Southeast is renowned for a remarkable 

diversity of amphibians, fishes, mollusks, 

crayfishes, and insects found nowhere 

else on Earth. Currently (2009), a steady 

increase in human population has led to 

the designation of the Southeast as one 

of the two fastest growing regions in the 

country. 

Heightened concerns about the 

projected consequences of global climate 

change are justified by the occurrence of 

recent weather events, such as the severe 

drought in 2007. Summer temperatures 

are expected to increase substantially 

during the 21st century in the Southeast, 

and the effects of drought and climate 

change on factors such as rainfall and soil 

moisture are uncertain. Some climate 

models suggest the duration and frequency of droughts will intensify in this 

region during La Niña phases as atmospheric carbon dioxide (CO2

) increases. 

Global climate change could lead to more 

periods of severe drought conditions.

This fact sheet summarizes the 

USGS capabilities to provide the science 

necessary for managers to effectively 

allocate limited water resources. 

Availability and 

Management of Water

Drought conditions directly affect 

streamflows, surface-water levels, 

ground-water levels, and ground-water/

surface-water exchanges that sustain 

river and spring flows. For example, 

extreme droughts have greatly reduced 

daily flows, cutting them to nearly half of 

the normal dry season flows for portions 

of the Chattahoochee and Flint Rivers in 

Georgia, and the Apalachicola River at 

Chattahoochee, Florida. These droughtrelated water flow and level declines, in 

turn, affect the economy and environment throughout the Southeast. During 

extreme drought conditions, there is 

insufficient water to meet demands for 

drinking water and irrigation, to provide 

adequate power generation, to support 

healthy populations of fish and other 

aquatic organisms, and to maintain floodplain forest and wetland habitats. 

As flows decline in streams during 

droughts, pollutants and other contaminants become more concentrated causing 

a decline in water quality. Coastal environments are also harmed by drought. 

For example, sufficient freshwater 

inflows are required for maintenance of 

low-salinity waters in estuarine areas. If 

freshwater flows are insufficient to create 

brackish conditions, then downstream 

fisheries in estuarine areas such as 

Apalachicola Bay are negatively 

impacted.

The USGS has a long history of 

working cooperatively with other Federal, State, and local agencies to provide 

important science and data concerning 

water availability and drought. For 

example, the USGS currently operates 

over 1,600 streamgaging stations in the 

Southeast that report data in real time, 

and hundreds more that provide surfacewater, ground-water, and water-quality 

data at daily and monthly intervals. 

USGS geographers and hydrologists 

have also compiled water withdrawal 

information and documented changes 

in water use patterns in various areas 

of the Southeast. USGS hydrologists 

In the Southeast, U.S. Geological Survey (USGS) 

scientists are researching issues through technical 

studies of water availability and quality, geologic processes 

(marine, coastal, and terrestrial), geographic complexity, 

and biological resources. The USGS is prepared to tackle 

multifaceted questions associated with global climate 

change and resulting weather patterns such as drought 

through expert scientific skill, innovative research 

approaches, and accurate information technology. 
also use these data to develop models to 

predict how increased water withdrawals, 

drought, and other stresses could affect 

water levels, streamflows, water quality 

and availability, and floodplain habitats. 

USGS scientists and technicians can provide the science and data necessary 

to gain a better understanding of droughtrelated effects on (1) ground- and 

surface-water quality and quantity, 

(2) water use, (3) rates and patterns of net 

precipitation (rainfall minus evapotranspiration) to the land surface and recharge 

to aquifers, (4) chemical transport and 

transformation in the unsaturated zone 

(between land surface and the water 

table), and (5) salinity intrusion.

Southeastern Biodiversity and 

Imperilment

Freshwater and floodplain habitats 

are essential for the survival of a very 

diverse group of animals—from salamanders to minnows. The Southeast is 

an area of great freshwater biodiversity 

compared to other temperate regions of 

the world. However, many animals in 

the Southeast are imperiled, meaning 

species are federally listed as endangered, 

threatened, or considered to be likely 

candidates due to their habitat conditions. 

More imperiled fishes occur in the freshwater ecoregions of the Southeast than 

anywhere else in the country. Recent 

severe droughts compound the stresses 

on aquatic habitats and species already 

imperiled. Without proper foresight and 

management, much of the aquatic biodiversity in the Southeast may be lost.

From bottom-dwelling invertebrates 

to amphibians, fishes, and alligators, 

USGS scientists are experts in studying a 

wide variety of aquatic organisms vulnerable to drought. Furthermore, USGS 

has a long history of reliably monitoring 

water quality and quantity, mapping natural resources, and modeling hydrologic, 

geological, and biological processes. 

Because of its integrated multidisciplinary approach, the USGS is uniquely 

qualified to address scientific questions 

that cross traditional research boundaries.

Drought in the Southeastern United States 

in 2007 and 2008.

Imperilment and biodiversity in the 

Southeast (American Fisheries Society 

Endangered Species Committee; Abell 

and others, 2000).

REGIONALLY

NATIONALLY

CONTINENTALLY

GLOBALLY

BIOLOGICAL

DISTINCTIVENESS

OF ECOREGION

EXPLANATION

0

0 500 KILOMETERS

500 MILES

0 - 8

9 - 16

17 - 23

24 - 30

31 - 58

NUMBER OF

IMPERILED TAXA

IN ECOREGION

EXPLANATION

0

0 500 KILOMETERS

500 MILES

Low rainfall and high ground-water pumping reduce amount of

ground water feeding stream, and may induce streamflow into aquifer

CONFINING BED

UNCONFINED AQUIFER

WATER TABLE

LAND SURFACE

STREAM

Relation among low rainfall, ground-water pumping, and streamflow.

DROUGHT SEVERITY

ABNORMALLY DRY

DROUGHT - MODERATE

DROUGHT - SEVERE

DROUGHT - EXTREME

DROUGHT - EXCEPTIONAL

EXPLANATION

April 8, 2008

October 9, 2007

FL

MS AL

GA

SC

NC

TN

FL

MS

AL

GA

SC

NC

TN
Invasive Species

Invasive non-native animals and 

plants can often tolerate a wide range of 

environmental conditions, thus they are 

better able to thrive in rapidly changing 

habitats than many native species. In a 

struggle for survival, non-native species 

may outcompete native species under 

drought conditions. Nearly 40 percent of 

the native fishes in North America are 

considered imperiled. The presence of 

invasive fishes and other invasive aquatic 

organisms is considered one of the main 

factors that has contributed to the decline 

and imperilment of these native fishes. 

Two examples of invasive species now 

established and threatening the Southeast 

are the flathead catfish and red shiner. 

The flathead catfish can reach 4 feet in 

length, weigh 100 pounds, and prey upon 

native fish. The red shiner, a small fish 

transplant from the Mississippi River 

basin, is abundant in some small streams 

and commonly hybridizes with native 

shiners.

The USGS has a long-standing 

commitment to documenting and understanding the effects of invasive animals 

and plants, as well as providing natural 

resource managers with control information. USGS researchers are investigating a wide range of issues, for example, 

invader-native species interactions, 

invader influence on ecosystem structure, 

and long-term ecological consequences 

of invasive species. On a national level, 

the USGS maintains the Nonindigenous 

Aquatic Species database, which includes 

a georeferenced history of documented 

aquatic introductions across the United 

States. This database currently contains 

over 73,000 records, many of these from 

the Southeast. The database allows users 

to perform space and time analyses of 

species occurrences, and distribution 

mapping. Because the database tracks 

the dispersal of non-native species, it 

functions as an early warning system 

when adjacent drainages or regions are 

newly invaded. 

At least 70 non-native aquatic animal and plant species have been documented in a single southeastern drainage, 

the Apalachicola-Chattahoochee-Flint 

(ACF) drainage. Several amphibians, 

various invertebrates (for example, 

freshwater jellyfish, copepods, crayfish), 

44 transplanted and foreign fishes, one 

mammal (the South American nutria), 

and almost 20 species of invasive aquatic 

plants have been documented as occurring in the drainage. The Asian swamp 

eel entered the ACF drainage in about 

1989; it is an air-breathing fish that preys 

on native animals. The Asian clam exists 

throughout the drainage, yet the extent to 

which it competes with native imperiled 

clams and mussels is unknown.

Contaminants

 Contaminants that may be present in the aquatic environment can be 

adversely affected by drought conditions. 

Lower rainfall amounts may result in 

increased concentrations of contaminants 

(and dissolved naturally occurring constituents) in ground water, streams, rivers, 

and lakes, posing an increased threat to 

aquatic organisms. These concentration 

increases could occur as a result of lower 

dilution capacity in rivers and lakes, and 

increased concentrations of chemical residues transported to ground and surface 

waters during first-flush rainfall events. 

Also, increased temperatures and lower 

water levels may alter biogeochemical 

transformation processes and potentially 

accelerate transformation of chemicals 

to degradational products, some of 

which can be more toxic than the parent 

chemicals. Adverse ecological impacts 

associated with “emerging contaminants” 

(including pharmaceuticals, pesticides, 

Flathead catfish

(Photograph by the USGS)

Asian swamp eel

(Photograph by the USGS)

0

50

100

150

200

250

300

Number of Species

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Cumulative number of fish species introduced into the Southeast by decade, 1900-2000.
and other synthetic chemicals) from 

municipal wastewater treatment facilities 

could increase as a result of drought and 

reduced dilution capabilities of streams 

and lakes. These impacts (which include 

disruption of endocrine functioning, 

growth, and sexual development) could 

increase, extend further downstream, and 

persist over longer periods during times 

of drought. Changes in aquatic community structure following reduced flows 

and water levels can impact organisms 

higher in the food chain with broader 

effects reaching into ecosystems. Understanding the effects of contaminants on 

aquatic species during times of drought 

is critical for assessing potential risks 

to human health from drinking-water 

sources and through the food chain, and 

for prioritizing contaminants for further 

human-health research. 

 USGS scientists have the capability 

and resources to investigate the influence 

of drought on the environmental risks 

of contaminants. The USGS is the lead 

federal agency for measuring long-term 

ground-water levels, streamflow, and 

water quality; developing water-quality 

sampling protocols; understanding the 

processes associated with contaminant 

occurrence, transport, and fate in water 

resources; and in field evaluations of contaminant effects on biota and ecosystems. 

The USGS water-quality laboratories 

are national leaders in methods development and analytical capabilities, and can 

assess a broad spectrum of contaminants 

at parts-per-billion and parts-per-trillion 

concentrations necessary to evaluate ecologic effects and temporal trends. USGS 

researchers are among the first to document endocrine disruption in biota, the 

occurrence of emerging contaminants in 

water, and their effects on biota. USGS 

scientists continue to serve in advisory 

capacities to other federal agencies and 

policymakers to address these issues. 

Iconic Species

 Iconic species serve as the “canary 

in the coal mine” for indicating the health 

and stability of an ecosystem. Iconic 

species are unique, readily recognizable, and considered to have intrinsic, 

aesthetic, or economic value to people. 

In the aquatic habitats of the Southeast, 

such species include the alligator, oyster, 

manatee, striped bass, and Gulf sturgeon. 

The effects of drought upon these aquatic 

species mirror the observed effects on 

most of the other native inhabitants of 

southeastern aquatic ecosystems; many 

are in trouble. Whether their declines 

are a result of overfishing, collisions 

with watercraft, or loss of habitat, these 

species are harmed further by habitat 

changes caused by drought and reduced 

water availability.

POULTRY

SUBURBAN

URBAN

FOREST

NEAR ATLANTA

ALL SITES

CROPLAND

(classic depostis)

CROPLAND

(carbonate bedrock)

UPSTREAM

FROM ATLANTA

DOWNSTREAM

FROM ATLANTA

2.0

1.5

1.0

0.5

A

0

VERAGE SUMMED PESTICIDE CONCENTRATION

PER SITE, IN MICROGRAMS PER LITER

TRIBUTARIES WITH ONE

PREDOMINANT LAND USE

LARGE RIVERS

WITH MIXED LAND USE

PIEDMONT COASTAL

PLAIN

PIEDMONT

INSECTICIDES

SELECTIVE POSTEMERGENCE

HERBICIDES

NONSELECTIVE HERBICIDES

SELECTIVE PREEMERGENCE

HERBICIDES

COASTAL

PLAIN

Relation between pesticide type, concentration, land use, and site location for 

the Apalachicola-Chattahoochee-Flint Rivers basin (Frick and others, 1998).

The following combination of 

physical and ecological expertise and 

data enables the USGS to place the present populations of iconic species and 

drought-affected habitats into a historical 

ecological context and provide scientifically based alternatives to managers:

•	 Gulf Sturgeon—More than two 

decades of scientific research; compilation and management of an Apalachicola River Gulf sturgeon mark-recapture 

population database containing 

22 years of data. 

•	 Manatees—Three decades of scientific 

research encompassing population 

modeling, satellite telemetry monitoring, genetics, integrated hydrology/

manatee models, and development of 

decision support tools; management 

of the interagency manatee photoidentification database containing over 

30 years of data.

•	 Alligators, Oysters, Food and Game 

Fish—Four decades of scientific 

research on the habitats, ecology, and 

effects of ecosystem restoration on 

these iconic species. 

•	 Water Level and Streamflow Monitoring—More than 100 years of monitoring hydrologic conditions throughout 

the Southeast; providing the physical 

data necessary to best determine the 

effects of drought on iconic species. 

West Indian manatee

(Photograph by the USGS Sirenia Project.)
References

Abell, R., Olson, D., Dinerstein, E., Hurley, 

P., Walters, S., Loucks, A., Allnutt, T., and 

Wettengel, W.W., 2000, A conservation 

assessment of the freshwater ecoregions of 

North America: Island Press, Washington, 

D.C., 319 p.

Barber, L.B., Lee, K.E., Swackhamer, D.L., 

and Schoenfuss, H.L., 2007, Reproductive responses of male fathead minnows 

exposed to wastewater treatment plant 

effluent, effluent treated with XAD8 resin, 

and an environmentally relevant mixture of 

alkylphenol compounds: Aquatic Toxicology, v. 82, no. 1, p. 36-46.

Benson, A.J., Fuller, P.L., and Jacono, C.C., 

2001, U.S. Geological Survey Summary 

Report of nonindigenous aquatic species 

in U.S. Fish and Wildlife Service Region 

4, 68 p.

Blazer, V.S., Iwanowicz, L.R., Iwanowicz, D.D., Smith, D.R., Young, J.A., 

Hedrick, J.D., Foster, S.W., and Reeser, 

S.J., 2007, Intersex (testicular oocytes) 

in smallmouth bass from the Potomac 

River and selected nearby drainages: 

Journal of Aquatic Animal Health, v. 19, 

no. 4, p. 242-253 [available at: http://afs.

allenpress.com/perlserv/?request=getabstract&doi=10:1577/H07-031.1 

accessed December 17, 2008.]

Bonde, R.K., Aguirre, A.A., and Powell, J.A., 

2004, Manatees as sentinels of marine ecosystem health: Are they the 2,000-pound 

canaries? EcoHealth 1, 255-262.

Darst, M.R., and Light, H.M., 2007, Drying of floodplain forests associated with 

water-level decline in the Apalachicola 

River, Florida—Interim results, 2006: U.S. 

Geological Survey Open-File Report 2007-

1019, 32 p.

Dorn, N.J., and Trexler, J.C., 2007, Crayfish 

assemblage shifts in a large drought-prone 

wetland: The roles of hydrology and 

competition. Freshwater Biology, V52: 

2399-2411.

Focazio, M.J., Kolpin, D.W., Barnes, K.K., 

Furong, E.T., Meyer, M.T., Zaugg, S.D., 

Barber, L.B., and Thurman, M.E., 2008, A 

national reconnaissance for pharmaceuticals and other organic wastewater contaminants in the United States – II) Untreated 

drinking water sources: Science of the 

Total Environment, dio:10.1016/j.scitotenv.2008.02.021, 16 p. [available at: http://

dx.doi.org/10.1016/j.scitotenv.2008.02.021 

accessed December 17, 2008.] 

Gulf sturgeon

(Photograph by Oscar Sosa, ©2007)

Apalachicola Icons: Oysters and Sturgeon

 No species is a more recognizable icon of the Apalachicola River 

ecosystem than the oyster, yielding $200 million in revenue to the local 

economy. Oysters require a delicate balance of fresh and salt water to 

thrive. The integrity of the Apalachicola River ecosystem is critical 

to the oyster and to people who depend on this species for their 

livelihood. Oysters and sturgeon are used by several resource 

agencies and public interest groups as hallmarks of the overall 

health and stability of rivers and estuaries. 

The sturgeon is a large iconic fish in several major U.S. 

river systems. When drought reduces springtime water levels, sturgeon spawning grounds over 150 kilometers inland 

can become dry and no spawning can occur. Along the Gulf 

Coast, impassable shoals and bars can prevent Gulf sturgeon 

from migrating upstream to spawn under drought conditions. 

During less severe droughts, stagnant river flow may provide 

insufficient dissolved oxygen for developing eggs and larvae. Additionally, pooled nutrients may stimulate massive algal 

blooms along the river bottom, prohibiting access to sand habitats 

where sturgeon and other bottom fish must feed. 

Drought effects extend beyond the freshwater reaches of rivers. 

Diminished freshwater input results in salinity intrusion into coastal bays 

and estuaries, eliminating the low and mid-salinity regions critical to sturgeon, 

oysters, and a host of other species. In late 2007, for example, highly saline water 

penetrated the entire Apalachicola Bay estuary, as well as the lower reaches of 

the Apalachicola River. 

As critical zones where rivers mix with the ocean, estuaries provide essential feeding grounds for sturgeon and oysters, both of which are harmed by 

reduced freshwater input. Specifically, juvenile Gulf sturgeon are jeopardized because they 

feed exclusively in estuaries, and oysters face a dual threat because their larvae require reduced salinities to settle and 

renew the oyster bars. Neither will be able to persist long under multi-year drought conditions that eliminate the 

food-rich brackish zone, depriving early juvenile sturgeon of estuarine food and preventing the oyster and many

 other estuarine-dependent species from repopulating. 
Integrated Science

The integrated nature of USGS 

scientific research enhances the ability 

of its scientists to address the complex 

biological, hydrological, and physical 

interrelationships that characterize the 

Southeast. Some of the capabilities of 

USGS scientists include:

•	 Research on fish and wildlife 

distribution, population dynamics, 

and ecology;

•	 Understanding the impacts of 

environmental stressors, such as 

invasive species and contaminants;

•	 Water monitoring and research;

•	 Image analysis and 

interpretation; 

•	 Development of models 

and adaptive management strategies to answer 

complex management 

questions; and

•	 Evaluation of ecosystemlevel questions regarding 

land use, water use and 

allocation, and the effects 

of changing land use on 

animals, plants, and 

ecosystems.

USGS CAPABILITIES

Sample of Research Datasets

Geology Geography

Parameter definitions

Changes over time

Water

Distributed flow and

associated statistics

Biology

Viability and range

of aquatic species

Impacts of stressors

Gilliom, R.J., Barbash, J.E., Crawford, C.G., 

Hamilton, P.A., Martin, J.D., Nakagaki, 

N., Nowell, L.H., Scott, J.C., Stackelberg, 

P.E., Thelin, G.P., and Wolock, D.M., 2006, 

The quality of our nation’s waters—Pesticides in the nation’s streams and ground 

water, 1992-2001: U.S. Geological Survey 

Circular 1291, p. 136 [available at: http://

pubs.usgs.gov/circ/2005/1291/ accessed 

December 17, 2008.] 

Frick, E.A., Hippe, D.J., Buell, G.R., Couch, 

C.A., Hopkins, E.H., Wangsness, D.J., and 

Garrett, J.W., 1998, Water quality in the 

Apalachicola-Chattahoochee-Flint River 

basin, Georgia, Alabama, and Florida, 

1992–95: U.S. Geological Survey Circular 

1164, p. 40.

Landers, M.N., and Painter, J.A., 2007, How 

much water is in the Apalachicola, Chattahoochee, and Flint Rivers, and how much 

is used? U.S. Geological Survey Fact 

Sheet 2007-3034, 4 p.

Light, H.M., Darst, M.R., and Grubbs, J.W., 

1998, Aquatic habitats in relation to river 

flow in the Apalachicola River floodplain, 

Florida: U.S. Geological Survey Professional Paper 1594, 77 p., 3 pls.

Marella, R.L., Fanning, J.L., and Mooty, 

W.S., 1993, Estimated use of water in the 

Apalachicola-Chattahoochee-Flint River 

basin during 1990, and trends in water use 

from 1970 to 1990: U.S. Geological Survey 

Water-Resources Investigations Report 

93-4084, 45 p.

For further information on USGS capabilities, please contact:

Jess Weaver Barry Rosen

Southeastern Regional Executive Center Director

3850 Holcomb Bridge Road, Suite 160 Florida Integrated Science Center

Norcross, GA 30092 12703 Research Parkway

(770) 409-7700 Orlando, FL 32826

jdweaver@usgs.gov (407) 803-5508

 brosen@usgs.gov

For further information on drought in the Southeast and USGS Science, please visit this 

website: http://fisc.er.usgs.gov/southeastdrought/

Myers, Mark, 2006, Testimony of USGS 

Director on “Ova-Pollution in the Potomac: 

Egg-Bearing Male Bass and Implications for Human and Ecological Health”: 

Oversight hearing of the U.S. Congressional Committee on Governmental 

Reform [available at: http://www.fws.gov/

laws/Testimony/109th/testimony_109.htm 

accessed December 17, 2008.] 

National Assessment Synthesis Team, 2000, 

Climate change impacts on the United 

States: The potential consequences of climate variability and change: U.S. Global 

Change Research Program, Washington, 

D.C.

USGS disciplines enhance research capabilities for determining long-term effects on complex systems.