United States • Office of Office of
Environmental Besearch and Water
Protection Agency Development
EPA/822/F-97/003April 1997
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Backwater area. Side channels and backwaters
provide breeding habitat and refuge for fish and
amphibians and contribute to the biodiversity of
the floodplain. 'fhese important ecosystems are
formed as the river migrates across the floodplain
during high flow periods. Lower flows caused
by diversions primarily to support agricultural
production facilitate conversion of these areas to
woodlands and often to cropland.
R A
What is an ecological risk assessment
n ecological risk assessment evaluates the poten-
tial adverse effects of human activities on the
I plants and animals that make up ecosystems.
The risk assessment process provides a way to develop,
organize and present scientific information so that it is
relevant to environmental decisions. When conducted
for a particular place such as a watershed, the ecologi-
cal risk assessment process can be used to identify
vulnerable and valued resources, prioritize data collec-
tion activities, and link human activities with their
potential effects. Risk assessments provide a focal
point for cooperation among local communities and
state and federal government agencies, and a basis for
comparing different management options.
COVER PHOTO: 'Nebraska. Game & Parks Commission
COVER: The middle Platte River valley has hemispherical significance as a staging
area for migratory water birds. The region is best known for the nearly one-half million
sandhill cranes (cover photo) and several million ducks and geese that migrate annually
through the region. Approximately 50 species of mammals and 300 species.of'migratory
birds use the woodlands, grasslands and wet meadows in the Platte River valley.
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Why is the middle Piaite Stiver special?
he Platte River flows eastward across Nebraska
providing water for irrigation, electric power,
recreation, fish, wildlife, and community and
industrial water supplies. The middle segment of this
river has national and international environmental
importance. It is the major staging (resting) area for
one-half million sandhill cranes and several million
ducks and geese that migrate annually through the
: area. Many other species of
mammals, birds and fish
including six endangered
or threatened fish and
bird species (such as the
whooping crane) use the
water, woodlands, remain-
ing native grasslands and
wet meadows in the middle
Platte River valley. Surface
and groundwater flows
• from this segment of the
Platte Elver system .are also important to the econom-
ic stability of central Nebraska by irrigating about two
million acres of land, mostly for corn production.
The middle
segment of the
Platte River flows
approximately
266 km (165
miles) from the
confluence of
the North and
South Platte
Rivers, in western
Nebraska, to its
confluence with
the Loup River.
Many resident and migratory birds require open sandbars and shallow
water for nesting and roosting. Reduced river flows have changed the
characteristics of the river, allowing shrubs and trees to colonize sand-
bars (as depicted in the photograph), forming islands surrounded by
deep water, thus 'decreasing critical habitat for these birds.
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Key stressors beiiig
evaluated in the.
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risk assessment brought together numerous organiza-
tions to analyze the impact of stressors on these
habitats and the wildlife populations in the watershed.
A report describing the management goals for the
Middle Platte River watershed and the analysis plan
for the assessment will be available upon completion
of the analysis described above.
How will the results be used?
ihe middle Platte River Ecological Risk
Assessment will help resource managers predict
how potential changes in land use and river
flow could affect the biological communities in the
watershed. This will enable resource managers to
make decisions based on more information. This
project is co-sponsored by the USEPA's Office of
Water and Office of Research and Development as
an effort to bring the science of risk assessment into
the local community decision-making process.
The U. S. Environmental Protection Agency thanks the following
for their participation in this assessment effort:
Central Nebraska Public Power and Irrigation District
Nebraska Public Power District
Nebraska Department of Environmental Quality
Nebraska Natural Resources Commission
Central Platte Natural Resources District
Nebraska Game and Parks Commission
Tri-Basin Natural Resources District
Nebraska Department of Agriculture
The Nature Conservancy
Prairie Plains Resources Institute
Platte River Whooping Crane Maintenance Trust
University of Nebraska — Lincoln and Kearney
US Fish and Wildlife Service
US Geological Survey
US Department of Agriculture
For more information, contact
Robert Fenemore (WWPD)
US EPA Region VII
726 Minnesota Avenue
Kansas City, KS 66101
(913) 551-7745
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