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513 B63 75SS
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MIDDLE PLATT
RIVER FLOQDPL AIN
Ecological Risk Assessment
Planning and Problem
. . ' ','-' C* . . .- _
Formulation
RISK ASSESSMENT FORUM
U. S. ENVIRONMENTAL PROTECTION AGENCY
DRAFT, June 17, 1996
RAF 024
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DRAFT , Review Draft
DO NOT QUOTE, CITE, OR DISTRIBUTE . J june
CENTRAL PLATTE RIVER FLOODPLAIN ECOSYSTEM
ECOLOGICAL RISK ASSESSMENT CASE STUDY
EXECUTIVE SUMMARY
Prepared for the
Risk Assessment Forum
U.S. Environmental Protection Agency
Washington, D.C.
NOTICE
THIS DOCUMENT IS A PRELIMINARY DRAFT: It has not been released by the U.S.
Environmental Protection Agency and should not at this state be construed to represent Agency
policy. It is being circulated for comment on its technical accuracy and policy implications.
Risk Assessment Forum
U.S. Environmental Protection Agency
Washington, D.C.
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DRAFT-DO NOT QUOTE, CITE, OR DISTRIBUTE
DISCLAIMER
This document is a draft for review purposes only and does not constitute Agency policy.
Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
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MEDDLE PLATTE ECOLOGICAL RISK ASSESSMENT TEAM
Name
Marcy, Suzanne
Fenimore, Robert
Jelinski, Dennis
Sefton, Donna
Craven, Harry
Currier, Paul
Downing, Maria
Ferguson, Jaci
Foster, Walt
Gardetto, Ed
Green, Pete
Huber, Annette
Huntsinger, Tom "
Jackson, Susan
Schweiger, William
Sidle, John
Thackray, Gillian
Welker, Gary
Anderbery, Rick
Bender, John
Kubicek, Terry
Lathrop, Brent
Miller, Kent
Moravek, Milt
Norman, Kenneth
Peters, Edward
Reiman, Richard
Rothenberger, Steve
Volk, Robert
Wallin, Jerry
Whitney, William
Zuerlein, Gene
Status
Chair
Associate Chair
Associate Chair
Former Assoc., Chair
Team Member
Team Member
Former Assoc. Chair
Team Member
Former'Assoc. Chair
Team Member
Team Member
Former Assoc. Chair
Team Member
Team Member
Team Member '
Team Member
Team Member
Team Member
Participant
Participant
Participant
Participant
Participant
Participant .
Participant
Participant
Participant
Participant
Participant
Participant
Participant
Participant
Affiliation .
EPA/ORD/NCEA
EPA/Reg. 7/ENSR
Univ, Nebraska-Lincoln - FFW
EPA/Reg. 7AVWPD
EPA/OPP
Platte R. Crane Trust .
EPA/Reg. 7/ENSV
EPA/Reg. 7/ARTX
EPA/Reg. 7/ENSV
EPA/OAR
EPA/Reg. 7/ENSV - - '
EPA/OW/OST
USGS -
EPA/OW/OST
EPA/Reg. 7/ENSV
USFWS \
EPA/OS W
EPA/Reg. 7/ENSV , . '
Tri-Basin Natural Resource District
Nebraska Dept. Environmental Quality
Nebraska Natural Resources Comm
Nature Conservancy
Twin Platte Natural Resource District
Central Platte Natural Resource District
SCS-Nebraska State Office
Univ. Nebraska-Lincoln - Fisheries
Nebraska Dept. Agriculture
Univ. Nebraska-Kearney
Univ. Nebraska-Lincoln - Water Center
Nebraska Natural Resources Comm.
Prairie Plains Res.
Nebraska Game and Parks Comm.
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CENTRAL PLATTE RIVER FLOODPLAIN ECOSYSTEM
ECOLOGICAL RISK ASSESSMENT CASE STUDY
EXECUTIVE SUMMARY
The central Platte River valley in Nebraska is an agricultural landscape that has undergone significant
transformation over the last century. Most of the native habitats have been extirpated or severely altered.
Numerous dams and water diversion projects in the upper Platte River basin have significantly reduced
natural flows and sediment discharge on the Platte River and, in consequence, once wide and treeless
channels have been transformed to multiple, narrow channels with woody vegetation succeeding on
sandbars. Peak discharge has declined nearly 70% over the last century, and the river channel is only 10-
70% of its 1865 width.' Wetland habitat has been reduced by 75%. There has also been widespread
alteration to the upland .landscape. Native vegetation now exists only as remnants (patches) within a matrix
of agricultural land. Intensive agriculture has replaced the majority of the native grasslands once found in
the area. Habitat loss and insularization of the biota have altered considerably the area's biodiversity and
threaten many of the remaining native populations and ecological processes.
The central Platte River valley also -has
hemispherical significance as a staging area for
migratory water birds, and offers critical habitat for a
variety of migratory and non-migratory birds (Figure
1). The region is best known for the nearly one-half
million sandhill cranes (Grus canadensis) and several
million ducks and geese that migrate annually through
the region; however, in total, approximately 50 species
of mammals and 300 species of migratory birds use
woodlands, grasslands and wetjneadows in the Platte
River valley. Six endangered or threatened species of
'birds are found on the Platte. "
Economic development in the central Platte
River valley is essential for local and regional
prosperity. Conserving biological resources and
maintaining the integrity of ecological processes must
be undertaken with consideration for economic
activities. A major conflict of economic development
on the Platte River revolves around water allocation for
irrigation, hydroelectric development, fish and wildlife,
and recreation. With more abundant water for
irrigation, intense row cropping has changed the land
cover of the watershed. Water resources are also
critically important for creating and modifying wildlife
Figure 1. The central flyway of North America.
(Source: PRWCMT 1996) '
habitat and for mediating ecological processes such as mineral and nutrient exchange across the flqodplain.
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Political controversy centers on trade-offs between irrigation and power development, biodiversity of the
floodplain ecosystem, and the maintenance of key ecosystem functions. The issues are complex and fraught
with emotion. ,
EPA Region VII formally nominated the central Platte River watershed in 1993 for inclusion in an
EPA sponsored project to develop watershed-scale ecological risk assessment case studies. Ecological risk
assessment provides a framework for conveying scientific information about ecological risks to managers
making environmental decisions. The risk assessment process is designed to ensure that assessment results
are both relevant to managers and scientifically sound. Cultural and ecological characteristics of the central
Platte River floodplain ecosystem have made attainment of these dual requirements particularly challenging.
As a consequence, the problem formulation phase of this risk assessment has undergone repeated, extensive
revision, and a substantial amount of work remains to be done. Conceptual models and the analysis plan
have received considerable thought; however, they are still under development and are not included in this
summary. ,
PLANNING THE RISK ASSESSMENT
The objectives,of the planning were to establish clear and agreed-upon goals for the watershed
resources, to determine the purpose for the risk assessment within the context of those goals, and to agree
on the scope and complexity of the risk assessment. One of the principal challenges for meeting planning
objectives for this risk assessment was to develop a management goal for watershed resources that diverse
members of the community could support. .
The Platte River drainage basin encompasses three states (Figure 2). The geographic scope of this
risk assessment includes the river reach extending from the dam at Lake McConaughy near North Platte,
Nebraska to the confluence with the Loup River near Columbus, Nebraska. The study area extends laterally
from the river channel to the edge of the historical floodplain at the Platte Valley escarpment.
Establishing the Environmental Management Goal
The management goal was formulated through an iterative process involving risk managers and risk
assessors, scientific advisors, and interested parties concerned about watershed resources. The process
included:
Watershed Tours/Visits, with Interested Parties
Focus Group Meetings
Symposia'and Public Forums
Early in the process meetings with interested parties focused on gathering information on
management goals, valued ecological resources, stressors, and ecological effects. Focus groups were
organized around agriculture, irrigation, and industry concerns; environmental and natural resource interests;
and government and university interests. Symposia and public forums were held at several stages in the
process to explain ecological risk assessment and exchange information relevant to the process. An equally
important function of these symposia and public forums was to obtain feedback on the prop6sed
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management goal, stressors, assessment endpoints, measures of effect, and proposed analysis plan
recognizing that all these components were still in the development stage. Formulation of the management
goal has been an iterative process in which the goal has been continually refined based on feedback from
interested parties, managers, and scientists. -
Uimun.
Platte River Drainage Basin
Figure 2. Platte River drainage basin.
The Environmental Management Goal
Protect, maintain, and where feasible, restore biodiversity and ecological processes in the
.. middle Platte Riverfloodplain to sustain and balance ecological values with human uses..
Interpreting the Management Goal for Risk Assessment
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The management goal is a qualitative statement that addresses concerns expressed by different
management organizations and the public in the central Platte River floodplain. The management goal
expressed herein defines the ecological values to be protected, but also recognizes the need to balance these
objectives with socio-economic concerns. Biodiversity is a prominent feature of the management goal. The
U.S. Office of Technology Assessment (1987) defines biodiversity as "the variety and variability among
living organisms, and the ecological complexes in which they occur". There are three scales over which
biodiversity can be measured: (1) genetic
diversity among individuals of a species,
(2) species diversity, and (3) community
and landscape diversity, 'For the'
purposes of this risk assessment concern
is with species, community, and
landscape diversity. .Our definition of
biodiversity also addresses the role of the
floodplain landscape mosaic (i.e., spatial
configuration) in affecting ecological
patterns and processes.
In order for the management goal
to support an ecological risk assessment,
the goal was evaluated by the Team and
interpreted as 11 management objectives
(see Table 1). These objectives "provide
the basis for interpreting the goal in the
risk assessment, selecting assessment
endpoints, and measuring the degree of'
success in achieving the goal. These
objectives are intended to state the
specific ecological characteristics of
principal interest to achieve the general
management goal. Furthermore, the
ecological values as embodied in the
management objectives provide a
framework for logical development of
assessment endpoints that can be directly
linked to the management goal.
The management objectives are
stated in Table 1, organized in relation to
landscape elements (ecosystems), and
recognizing that the middle Platte River
floodplain is a three-dimensional,
volumetric unit composed of river
channel, sandbar, backwater, riparian
forest and grassland ecosystems. The
Table 1. The environmental management goal for the middle Platte River
floodplain interpreted as 11 environmental management objectives that
are implicit in and required to achieve the management goal.
Affected Area Objective Environmental Management Objective
Channel
Riparian
Forest
Backwaters
Floodplain
Landscape
10
11
Restore and maintain stream channel dyn-
amic equilibrium.
Maintain, sufficient flows to prevent high
temperatures detrimental to native fish pop-
ulations.
Maintain range of successional stages of
forest vegetation. .
Maintain .and reestablish backwater
ecosystems
Maintain and restore hydrologic connectivity
between backwaters and river channels
through surface flows.
Maintain hydrologic connectivity between
river channels and wet meadow ecosystems.
Maintain and reestablish natural diversify in
wet meadow ecosystems.
Maintain and reestablish natural diversity in
native upland ecosystems.
Protect'and where feasible reestablish the
mosaic of habitats in the central Platte River
floodplain to support key ecological functions
and native biodiversity.
Maintain diversity of water-dependent wild-
life including migratory and nesting birds,
mammals, amphibians, reptiles and inverte-
brates.
Prevent toxic levels of contamination in water
consistent with state water quality standards.
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Team-determined that partitioning of the landscape by ecosystem type facilitates identification of assessment
endpoints and, ultimately, environmental management. -
In the central Platte River floodplain ecosystem, movement of water is the dominant force driving
many physical-hydrogeologic processes. The physical-hydrologic processes both directly and indirectly
support and maintain biodiversity. Given the importance of hydrology, four of the management objectives
explicitly recognize the need for maintaining or mimicking a hydrologic regime capable of maintaining'the
structure and function of the river floodplain ecosystem. Structure, here, refers to the composition of
habitats, their spatial arrangement (geometry), and the way in which they are connected and used by
organisms or to facilitate, an ecological process. Function refers to flows of energy, materials and organisms.
The management objectives focus on key groups of organisms or landscape elements (ecosystems).
Given .the importance of hydrology in maintaining this ecosystem, an important management
decision is to what extent, arid how, the current hydrologic regime should be altered to restore and maintain
the landscape mosaic and the ecosystems it comprises. A relevant ecological question is, to what extent can
changes in the hydrologic regime restore and maintain the system? Because of competing water uses, it may
not be feasible to alter the current hydrologic regime sufficiently to restore and maintain the system.
Managers must consider the-efficacy of alternative management methods such as channel clearing and the
implications that approach has for neotropical migratory birds. Historically, neotropical migrants were aa
minor component of the native avifauna. Neotropical migrants have experienced significant habitat loss
elsewhere and now utilize riparian woodlands that have become established on what was once open channel
habitat. . ' . ' -
Land use conversion from wet meadow to cropland and other intensive uses is .another potential
source of habitat loss. Finally, agricultural .chemicals (i.e. pesticides, herbicides, and fertilizers) have the
potential to degrade'the floodplain ecosystem, through toxicity and eutrophication. This is especially true
given the extensive connections between groundwater and surface water; however, the potential effects of
agricultural chemicals maybe insignificant compared to other'sources of stress. Managers must decide
where to focus their limited resources to obtain maximum ecological benefits. Estimates of ecological risk
can be useful for prioritizing management actions and identifying land parcels for special protective
measures.
Assessment Endpoints
Assessment endpoints are explicit expressions of the actual environmental values to be protected.
The assessment endpoints translate the management,goals into ecological endpoints that are susceptible to
one or more stressors. Assessment endpoints must be directly or indirectly quantifiable; however,
identification of these assessment endpoints does not imply that the data needed to make these quantitative
determinations necessarily exist for the Platte River watershed, Rather, the assessment endpoints provide
a framework and focus for data collection. The assessment endpoints also serve a critical function in the
problem formulation because they provide the basis for conceptual model development, which is the process
of portraying the functional relationships among assessment endpoints and their predicted responses to
strp.ssnrs , .
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Assessment endpoints were defined and selected based on three criteria: (1) how well they represent
the management goal (societal value); (2) how well they represent attributes of the ecological integrity of
the middle Platte River floodplain (ecological relevance); and (3) the likelihood they will be adversely
affected by one or more stressors (susceptibility). The assessment endpoints are listed in Table 2 in relation
to the management objectives they address. ,
There is a certain amount of redundancy among landscape-, ecosystem-, and population/eommunity-
level assessment endpoints. The apparent redundancy derives from three observations made by the Team:
(1) Each level of assessment has different criteria for observation and measurement; thus, each provides a
different vantage point for assessment; (2) Individual species and animal communities are of special concern
to managers and they are important in determining success of management actions; however, species cannot
be managed in isolation from their habitats; and (3) Scientific understanding of ecosystems is not adequate
to ensure that apparent ecosystem-level integrity will be protective of all species and communities of special
concern. Redundancy across levels of biological organization is an acknowledgement of these factors and
defines the Team's approach to addressing them.
Table 2. Assessment endpoints for the middle Platte River floodplain risk assessment organized by the level of
assessment, and the management objectives they address.
Level of
Assessment
Landscape
Ecosystem
Population/
Community
Assessment Endpoint
Floodplain landscape-mosaic structure and
function.
Open channel configuration and distribution.
Channel and backwater structure and function.
Riparian vegetation successional stage, areal
extent, and dispersion.
Wet meadow ecosystem structure and function.
Migratory water-bird diversity, abundance,'
and dispersion.
Sandbar,- grassland, and neotropical avifauna
survival and reproduction.
Amphibian survival and reproduction.
Riverine and backwater fish and invertebrate
community structure and function.
12
X X
X
X
X
X
X
X X
X
X X
Management Objective
2 4 ' 5 6 2 £ £
X X X X X X X
X
XXX X
X X
X X X X X
X X
XX XXX
X X
X X
10
X
X
X
X
X
X
X
X
11
X
X
X
X
X
X-
X
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Landscape-level assessment endpoint .' v .
Floodplain landscape-mosaic structure and function. The floodplain mosaic, including its structure and
function, was chosen as an assessment endpoint because the patchwork of ecosystem types, interactions
among those ecosystem types, and maintenance of landscape-scale processes are all necessary to achieve
the management goal. Biodiversity and ecological processes of the floodplain depend upon a landscape-
scale, shifting mosaic of habitat types. The predominant landscape-level stressors are hydrologic
modification and conversion of land cover from native habitats to cropland and other intensive human uses.
Ecosystem-level Endpoints .
.Open channel configuration and distribution. The middle Platte River is a braided stream with active
sandbars and bedload movement. Periodic floods establish new channels that migrate across the floodplain
forming a braided network. The flood pulse scours' sandbars on which vegetation may be established thus
maintaining channels in an open cpndition. Open channels provide nesting habitat for least terns and piping
plovers and roosting habitat for sandhill cranes, whooping cranes, and waterfowl. The distribution of open
channel habitat controls the distribution of these avian species. Therefore, open channel configuration and
distribution, were selected as measurable attributes.for restoring and maintaining the dynamic equilibrium
characteristic of large braided rivers. When floods are reduced in magnitude and frequency, the riverbed
does not shift which results in increased stability of the bars and, ultimately, establishment of vegetation
The dominant factor causing loss of open channel habitat and expansion of riparian woodland appears to
be reduction in the magnitude and variability of surface water flows.
Side channel and backwater structure and function. Side channels and backwaters provide breeding
habitat and refugia for fish and amphibians, and floodplain nutrient sink/source functions. The structure and''.
function of side channel and backwater ecosystems contributes to the biodiversity of the floodplain and
maintenance of important landscape processes. Side channels and backwaters are formed by scouring and
migration of river flows. When the main channel no longer avulses (i.e. does hot cut across the floodplain
forming new channel paths) backwaters 'and side channels gradually grade toward terrestrialization often
being replaced by Woodland vegetation. Lower, more stable flows also facilitate conversion of these
ecosystems to cropland.
Riparian vegetation successional stage, areal extent, and dispersion. Riparian habitats support a
disproportionately large amount and diversity of biota. Alteration of the riparian woodlands affects
biodiversity, water quality, and other ecosystem functions: At the same time, alluvial riparian woodlands
adversely affect sandhill cranes and other channel roosting water-birds that, prefer unobstructed views of the
landscape. 'Diversity in alluvial forest succession is maintained by river channel migration simultaneously
depositing alluvium and eroding vegetated sandbars and banks. The attributes are key to maintaining
woodlands in a dynamic equilibrium with many patches (areal extent and dispersion) in various successional
stages. Reductions in the magnitude and variability of river flows results in an increase in the areal extent
of riparian habitats in more advanced successional stages. - .
Wet meadow vegetation composition and abundance. Wet meadows are an ecosystem type in floodplains
characterized by poor soil drainage, high water tables and nutrient-rich soils. They support more than 200
plant species and a range of wildlife. They also support a variety of invertebrates that are an important
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source of high quality nutrition for sandhill cranes. Of fundamental significance is the hydrologic control
of the groundwater regime by connections to flows in the nearby Platte River. Wet meadow community
Structure is highly sensitive to small-scale topographic changes (i.e. ridge vs. swale) with corresponding
changes in productivity.
Population and Community-level Endpoints ,
Migratory waterbird diversity, abundance, and dispersion. Channels of the middle Platte River are used
as a staging area for a range of migratory waterbirds including sandhill cranes, whooping cranes, and a
variety of ducks and geese. Allare highly valued ecological resources. Approximately 80% (about 500,000)
of the continental population of sandhill cranes spend upwards of six weeks staging on the middle Platte
River. Sandhill cranes roost in open channels and forage for invertebrates in nearby .wet meadows and waste
corn in cornfields. This species has tremendously high societal value, attracting visitors from around the
world. The population is susceptible to displacement by narrowing of channel habitats forcing birds into
fewer reaches of the river with channels at least 150m wide, which is believed to be preferred habitat. They
are also susceptible to hydrological changes in wet meadows that affect numbers of invertebrates
(earthworms and snails), a critical component in the diet of sandhill cranes.
Several million ducks and geese use the middle Platte River region each year. They depend on open
channel habitats for roosting and feeding. Reductions in water levels causes crowding and attendant stress,
and increased probability of disease transmission (e.g. fowl cholera).
Piping plover, least tern, core grassland, and neotropical migrant survival and reproduction. The
floodplain supports a rich assemblage of breeding birds which are principally found in sandbar, woodland,
and wet meadow habitats. Least terns and piping plovers depend solely on unvegetated sandbar habitats for
nesting. Feeding sites must be free of disturbance with continuous water flow within 100m of the roost.
Core (i.e. not edge) grassland species serve as sensitive indicators of wet meadow habitat fragmentation.
The core-grassland bird species that rely on wet meadow habitats for breeding include upland sandpiper,
bobolink, grasshopper sparrow, dickscissel, and meadowlark. Fragmentation reduces their incidence and
abundance. Neotropical migrants serve as sensitive indicators of diversity for woodland breeding birds. The
susceptibility of neotropical migrants to shifts in homogeneity of forest structure makes this group of species
the best indicator of diversity in woodland succession.
Amphibian survival and reproduction. Because of their dependence on both aquatic and terrestrial
habitats, amphibians are good indicators of the structure and function of these habitat types and habitat
mosaic. Backwaters and wet meadows are particularly important for reproduction, and the suitability of
these habitats for spawning is strongly influenced by the hydrologic regime. General baseflow and episodic
inundation of lowlands create wetlands and ephemeral pools that are essential spawning and brood sites for
amphibian reproduction. Adults are more sensitive to upland conditions and can be adversely affected by
use of wet meadows and riparian woodlands by livestock and conversion to cultivated agriculture.
Hydrologic changes have the dual effect of eliminating the wetland habitats and facilitating conversion to
cultivated agriculture.
Riverine and backwater fish and invertebrate community structure and function. River channels and
backwaters support a variety of fishes and aquatic invertebrates which in turn support, either directly or
8 :..
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indirectly, recreational fisheries, and provide forage for birds and wildlife. These communities are also
important parts of the biodiversity of the Platte River floodplain. The fish communities of these habitats
includes the pallid sturgeon (Scaphirhynchus albus) which is a federally listed endangered species Fish
species that are candidates for federal listing include lake sturgeon (Acipenser fulvescens) paddlefish
(Polydon spathuld), sturgeon chub (Hybopsis gellda), sicklefin chub (Hybopsis meeki) and plains
topminnow (Fundulus Sciadicus). The fish and invertebrate communities are placed at risk by changes in
their physical habitat that derive from hydrologic alteration, including deleterious increases in water
temperatures during summer. Agricultural chemicals are an additional source of risk to these communities
The extensive connection between groundwater and surface water in the floodplain increases the capacity
for agricultural chemicals to migrate from the point of application and enter surface waters where they can
adversely affect fish and aquatic invertebrates..
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1 ' - . - .
2 APPENDIX B. Management Concerns
3 ' ' . "." ' - ,' '. ' .
4 '-.,,. '.''. : '"'
5 There are literally hundreds of entities whose managers make decisions managing or
6 impacting the resources of the Middle Platte area: Representative entities/managers
7 include local resource users, such as farmers, Central Nebraska Public Power and
8 Irrigation District, Platte River Whooping Crane Habitat Maintenance Trust, City of
9 , Grand Island, Grand Island Chamber of Commerce, Central Platte Natural Resources
10 District, and at the state level, the Ne.braska Game and Parks Commission.
11 Regulators also impact on resources of the Platte, such as the Environmental
12 Protection Agency (EPA), Department of Health, Department of Environmental
13 Quality, Department of Water Resources, and the Central Platte NRD. The variety of
14 concerns about the management of ecological resources in the watershed is presented
15 for each of these entities below.
16 , ;_.'" ' . . "..-'_"..''. ".'..'..'
17 Resources users - Local * - .
18 Farmers economic survival depends on profitable crop production, which typically
19 involves intensive use of land. Economic incentives, such as property taxes, force
20 wet meadow .conversion to cropland (or intensively grazed pasture). Crop production
21 typically requires intensive use of inputs, including fertilizer and pesticides, but this
22 use contaminates drinking water. Livestock production sometimes uses riparian areas
23 for water and shelter (windbreaks), and may require grazing and management of wet
24 meadows. ' , . . ' .
25 ' . .-' ' . ' ' . " ' - .'"".' , . ' '-
26 Central Nebraska Public Power and Irrigation District manages Lake McConaughy,
27 the supply canal, hydroelectric plants and irrigation service for the Middle Platte.
28 There are a number of associated concerns, including: project re-licensing; economic
29 viability of farmer/irrigators and the district itself; recreation, fish and wildlife in
30 Lake McConaughy versus the Middle Platte River; meeting instream flow
31 requirements of FERC and the State of Nebraska for threatened and endangered
32 species; meeting NPDES permit water quality requirements with discharge of Lake
33 , McConaughy in Keystone Lake without jeopardizing generation of electric power;
34 t pressure from riparian landowners to reduce discharges to avoid flooding caused by
35 lower channel capacity resulting from past district operations; effectiveness of
'36 constructing nesting habitat for threatened and endangered species in the Middle
37 Platte River, arid finally, the impacts on other resources.
38 ',.'.' .-..:.. . . . . -.
39 Platte River Whooping Crane Habitat Maintenance Trust works to maintain sufficient
40 habitat for the endangered whooping crane. To achieve this goal, the Trust
41 mechanically clears vegetation from the river channel for crane roosting habitat as a
42 substitute for former natural systems, such as scouring flows. Riparian vegetation is
43 also cleared to provide adequate sight distances to replace natural forces that are '
''.- ' ". . A2 ' . '~'..
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_ 1 notAS fully understood. Other involvement in the watershed includes: obtaining land
2 rights to wet meadows and riparian land from willing sellers and paying taxes on the
3 land (this use of financial resources causes varying public reactions); maintaining
4 relations with landowners and neighbors who lease the trust's land for grazing or
5 cropland; advocating adequate flows in the river to maintain the habitat; maintaining
6 habitat while providing opportunities for the public to view the migrating cranes and
7 provide good public relations. ,-
8 , . -..''..
9 The City of Grand Island provides municipal services, including public water supply,'
10 .waste water treatment, and electric power. Related management issues include:
11 , whether there is adequate flow in the river to (1) supply .enough water to the well field
12 and (2) to prevent the encroachment of ground water from cropland,in the uplands
13 that is contaminated with nitrate; taking action in state water rights proceedings to
14 protect the supply of water in the river without antagonizing the farmers^ who trade in
15 the city, to prevent the threat of another boycott; meeting the NPDES requirements
16 for the waste water treatment plant discharges; and, having adequate water supplies
17 for the municipal power plant. '
18 .
19 Grand Island Chamber of Commerce, both staff and members such as motels and
20 restaurants, are concerned about maintaining crane habitat and populations and
21 providing viewing-opportunities to maintain and increase tourism.
22 . /-.-.'.
23 Central Platte Natural Resources District (NRD) initiated management of the Platte in
24 the provision of instream flows, construction of recreation facilities, and planning and
25 applying for a water right for a diversion for a ground water storage/irrigation project
26 (Prairie Bend). Associated issues include: statutory responsibility for obtaining and
27 holding instream flow rights; providing recreational opportunities for viewing
28 ' migratory birds; developing an economically viable project for stabilizing ground
29 water levels; and reducing the concentration of nitrate in the ground water by storing
30 supplemental irrigation supplies from the river underground, while leaving sufficient
31 water in the river to meet instream flow requirements.
32 '."-..-'
33 'Resources users.- State , :
34 Nebraska Game and Parks Commission initiatives by the G&PC create concerns that
35 include providing fisheries, wildlife habitat, and recreation lands and opportunities in
36 the Middle Platte without reducing the same in Lake McCoriaughy; obtaining
37 instream flow rights to provide flows not covered by the Central Platte NRD's right.
38 '
39 Regulators - Local
40 Local concerns in the Central Platte NRD are described below according to stressor ;
41 type, namely: nonpoint and point sources, hydrologic modifications, recreation, and
42 'atmospheric inputs.
43
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.. 1 Nonpoint sources (i.e. surface runoff, nutrients and pesticides) are not believed a
2 serious problem in the Middle Platte Basin..Because of the flat terrain, the runoff
3 tends to lose much of the sediment before it reaches the Platte River. NRD's are
4 required by state law'to have a sediment and erosion control plan that requires cover
5 on all highly credible cropland. <
6 '.'':' '-.-.' ..,..'-.
7 One of the local concerns about surface water contamination is the distance between
8 quality monitoring stations on the Platte River. Certain contaminants are detected in
9 the river, however, the point of contamination is uncertain/Another concern involves
10 ; the timing of the samples; most samples are collected at maximum flows, when the
11. highest level of contamination is probable. This level is short lived and clearly not
12 the mean. USGS,NDEQ,NDOH and NRD's are jointly responsible for this
13 management in this area; '
14 ' . . ' ' ' :..,"
15 Leaching of .contaminants is designated as the responsibility of the NRD's through
1 16 state law. Central Platte NRD and Tri-Basin NRD have Groundwater Management
17 Plans in effect to address this problem. Because of. wide variations in groundwater
18 contamination, the solutions are primarily local. Potable drinking water is a necessity
19 for people living in the area and therefore is a concern of all.
20 . : , "'.'' '
21 Wetlands have been identified throughout the area and it is illegal to drain or place fill
22 material in wetlands without a permit. Determination of wetlands is the responsibility
, 23 of the Soil Conservation Service.
24-. '....,-''"'.'.'' . ' , ' , . ' ' ,
25 Livestock grazing or overgrazing is not known to be a problem in this area. The only
26 way to manage this is through the farmer-rancher. Proper management of livestock
27 grazing is simple economics for most ranchers and practiced in most instances
OS ' . '.'. .-":
Z5 . . . . . . I
29 . Hydrologic changes, such as surface water irrigation and hydropower is of
30. tremendous concern to the public, both local and statewide. Management practices in
31 this area must address economic impact both locally and statewide. Flow patterns
32 have^changed from what they were historically, however, the habitat has changed
33 rather than destroyed. Return flows from both irrigation and hydropower must be
34 recognized. Shrubs and trees on the sandbars are at the point now where it is not
35 realistic to consider scouring flows beneficial unless sandbars are mechanically
36 cleared. Flows adequate to clear these bars would create flooding throughout the river
37 / valley. Surface water irrigation and groundwater withdrawal have reached a balance
38 on the south side of the river at present time. Irrigation and hydroelectric return flows
39 - have improved summertime flows when the river was historically dry
40 . " . '."-.'... ' ...'''-'
41 The State Department of Water Resources is responsible for river flows at the present.
42 time. The state through Governor Nelson has developed an instream flow plan that is
43 acceptable on the state level and therefore it may be logical to use this plan for
''...'' ' . . ' ' ' A4 ...-''."
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1 management. Federal Regulations on River Flows would override state laws that now
2 exist. It must be recognized that changes in these flows in any way probably will have
3 a direct effect on the economy of the area. Variability in climate has a definite impact
4 on hydrological changes in the river". Through the use of irrigation storage facilities
5 we can now regulate the river flows to a certain extent, however, we must still be
6 dependent on snowfall and rainfall. Previous to this the river went from flood stage to -
7 a dry river in the same year as the climate dictated.
8 .
9 Feedlots could become a problem for point source pollution because they are .
10 becoming larger and more concentrated. Most feedlots over a certain head capacity
11' are required by the NDEQ to install pits to handle manure runoff. .This has not been
12 'enforced as it should be and therefore problems have erupted in this area. The NDEQ
13 should remain the agency responsible for feedlots, however, enforcement must be
14 stepped up. Local interests are concerned about this problem and hopefully public
15 pressure will create better enforcement. '
16 ' '
17 Point source pollution on the commercial, industrial arid municipal levels will be
18- addressed through Wellhead Protection Areas. These areas are designed to identify all
19 possible point sources of pollution and develop a time of travel from contamination
20 point to the municipal well fields. This is an EPA approved program offered through
21 NDEQ. Many municipalities have gone through the process of developing these
22 areas, however, many are reluctant because it is a labor intense process. This
23 identification is required in the new NRD Groundwater Quality Management Plan
24 and therefore-NRD's will probably be pressuring to get this accomplished. '
25 ' " ' ' ' '-.-.. .'.,';.'..-.
26 Unpermitted landfills should be a thing of the past in the Platte Valley. It is illegal to
27 : have any type of landfill except for burning trees. Farmsteads are no longer allowed
28 to even have private landfills. The penalty for noncompliance is stringent enough that
29 they probably will no .longer exist. . ,
30 . '
31 Nebraska Game and Parks is responsible for administering regulation of recreational
32 activities. Some of these activities are not only disruptive to wildlife, but also to
33 property owners in the area. ,
34 - , ' .''.'-
35 ' Monitoring of atmospheric inputs will have to continue to determine if any pollution
36 of this kind does materialize. The "tunnel" of exhaust along 1-80 may be too far out
37 to be considered a stressor in this report.
38 .
39 ' ' .
40 Regulators - State . .
41 ' Department.of Health concerns include the adequacy of the quantity and quality of
42 flows in the river to provide a suitable water supply for public water suppliers in the ,
43 middle Platte area.
A5
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1 The Department of Environmental Quality, responsible for surface and ground water
2 quality, is concerned with the -adequacy of water supplies for human consumption,
3' recreation, fish and wildlife, and protection of wetlands.
4 " .; _ ' ' ' ' '" '.,-,;. ; , .' ...
5 The Department of Water Resources is responsible for regulating the quantity of
6 , .surface water. Management concerns relate to the protection of rights of irrigators
7 and other water right holders; and the protection of threatened and endangered species
8 in granting water rights. . -
9 ' ' ' ' '. .. -. ' . "'.-.'."
10 Regulators - Federal .;...,
11 . The surface waters of the' middle Platte River basin are designated"for the following
12 uses in Nebraska Water Quality Standards: Recreation Class A (whole body contact -
13 204 miles); .Aquatic Life (607 miles); Agricultural Water Supply {607 miles); and
14 Industrial Water Supply (66 miles) (NDEQ. 1992). The Platte River alluvial aquifer
15 , also serves as the primary drinking water .source for citizens in the Middle-Platte
16 watershed. The Nebraska Department of, Environmental Quality is delegated
17- responsibility by the U.S. Department of Environmental Protection Agency under the
18 Clean Water. Act to implement programs to control sources of pollution to maintain
19 the physical, chemical, and biological integrity of the nation's waters.
20 , .-.. '. ; ; ' ; - - .' '
21- Federal legislation such as the Clean Water Act, National Environmental Policy Act,'
22 Endangered Species Act, Federal Insecticide, Fungicide, and Rodenticide Act, Safe
23 Drinking Water Act, and Resource Conservation and Recovery Act provide mandates
24 . which govern federal agency involvement in natural resource conservation and
25 ecosystem protection. Administration priorities include sustainable development;
26 pollution prevention; ecosystem management/geographical targeting; employing
27 sound science in decision-making; biodiversity protection; and building state and
.28 local capacity to deal with environmental issues. These management concerns have a
29 bearing on the Middle Platte ecological risk assessment
30 ' ,- . ...-.-.".. . ' "- ' ,
31 ; " ' -'- "'.-'' '.-''
32 : . , ' ' ''".-. '... ''
33 '". , ' ' *'- ' " ' . :.
'34. "-. '". ',' ' - . ''.'.. .'/.. ' '
'35 '''.'."' "".".''..'-''
36 . .-.'-'..'. ' '' ' ''..--.
37 ' - ' ' . ' ' '.--.- . .
38 ..-.''' ' ' : . '
39 . - . '.. . ' ', " '-' :
40 ' " .--.'. ',- ,'.. :
41 . ' , ' - -- ' - '.
42 ' ' ' " . ' . - .
43 ', ' ". : ' ' .
.- ' " ' A6 '-" ' '
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1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
APPENDIX C. Major Sources of Stress and Rankings in the Middle Platte River
Watershed . ',
Platte Sfressnr (Characteristics
J
SOURCE OF STRESS
NONPOINT SOURCES:
Farming practices
NONPOINT SOURCES:
Livestock grazing
NONPOINT SOURCES:
Urban, Residential,
Commercial Development
HYDROLOGIC
MODIFICATION: Surface
Water Irrigation, Hydropower
HYDROLOGIC
MODIFICATION:
Groundwater Irrigation
EXPLANATION (mechanism, stressor)
Surface Runoff (to ponds & streams'):
nutrients, pesticides
Leachina fto eroundwater): nitrates, pesticides
Aerial Drift of Chemicals: wet meadow
habitat alteration ,
Ae. Expansion: wetland habitat loss
Cattle Access to Streams: habitat destruction
(mussel beds, wet meadows, stream banks)
Overgrazing/Trampling: habitat alteration
(wet meadows structure)
Septic Svstem Drainage: GW/SW'
contamination by nutrients, pathogens .
Lawn Chemical Runoff: nutrients, pesticides
Runoff from parking lots, highways: nutrients.
toxics
Soills from Proposed Airoort alone ISOrtoxics
Water Withdrawals/Flow Alterations: stream
flow pattern disruption, channel, floodplain
alteration, instream, riparian and floodplain
.habitat loss . .
Water Withdrawals: water table alteration.
floodplain habitat alteration
-. Rank (0-3)
2
3 ' ;
i
2
2 (local)
1 (watershed)
2 (local)
1 (watershed)
1
.3 . . ' '
3
A7
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HYDROLOGIC
MODIFICATION: Municipal
. & Industrial Water Supplies
HYDROLOGIC
MODIFICATION:
Channelization
HYDROLOGIC
MODIFICATION: structures
FLOODPLAIN
DEVELOPMENT: Sand &
gravel operations .
FLOODPLAIN
DEVELOPMENT:
Residential
FLOODPLAIN
DEVELOPMENT: .
Transportation
CLIMATE VARIABILITY
POINT SOURCES: Feedlots
POINT SOURCES:
Commercial, industrial,
municipal, LUSTs,
unpermitted
EXOTIC SPECIES
' /
RECREATIONAL
ACTIVITIES: Off Road
Vehicles, Air Boats and other
Disturbance
Water Quality Changes: altered temperate
and DO, stream flow pattern disruption, '
sediment, nutrients, toxics
Habitat Loss/Alteration: wet meadows, >
primarily adjacent to tributaries
Habitat Loss/Alteration: Wet 'meadows
Habitat Loss: Wet meadows
Habitat Loss: Wet meadows
Habitat Loss: Wet meadows, pritri^ farmland
riparian . .
Habitat Loss/Alteration
Surface Runoff: Pathogens, nutrients
Leaching to Groundwater: pathogens
nutrients '
Groundwater: . ,
Industrial Discharges: RD3C, metals, tos,
BQD,NH3
Illegal Dumping: Toxics, pesticide?
Leachine from NPL/RCRA Sites: Tovirs,
metals
Leadline from LUSTs, Landfills- TOY!
metals
Surface Water: '
POTW Discharges: Ammonia, ROD,
nutrients, metals, pathogens
Altered patterns of plant colonization and
competition ,
Loss of diversitv
Streambank Erosion. Harassment of Wildlife:
sediment, nutrients, population pressures
Takine of Wildlife/Fish: population pressures
2 (local)
1 (watershed)
2 , '
2 .
3 ' ^ '
2 , '' . . ''.'. ''
2 ,
2 .
2 - '..' ' '
2 (local) 1-2
(watershed)
2.
2
2 (local)
1 (watershed) 7 ,
1
A8
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3
4
5
6
7
8
'9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
ATMOSPHERIC INPUTS:
Power Plants and
Transportation .
Air Deposition: exhaust from
highways, toxics, industrial emissions
APPENDIX D. Observed ecological effects of stress in the Middle Platte
Watershed
I Class I Ecological Effect
Citation
Habitat.
Habitat
Habitat
Habitat
Biota
Biota
Biota
Biota
Biota
23-45% loss of wet meadows 1938-1982
Increase in riparian forest from 29% to 75.% of habitat
Development of forested corridor allowed hybridization
among east/west species
Structural diversity in wet meadows reduced
Fewer aquatic birds, more woodland birds nesting in trees
in riaprian corridor
Few white pelicans rest in areas of riparian forest and
narrow channels (need areas without nearby predator
cover)
Loss of least tern and piping plover habitat (open
sandbars) '
Shift in sandhill crane distribution: no longer found west
of Kearney
Avian cholera outbreaks result from overcrowding in
smaller habitat patches (killed > 200 k since 1975) .
Sidle, 1989; Gunigo, 1990; Currier
'anc. 93 . . ;
Sidle, et al.' 1989
Savidge anc. 93; (Short) ,
Currier, anc. 93
Sidle,. anc. 93
Sidle, etal. 1990
O'Brien & Currier, 1987
Sidle, anc. 93
Gunigo, et al. 1990 :
A9
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1
2
3
4.
' 5
Biota
Biota
Biota
Biota
Biota
- : >
Biota
Loss of biodiversity (primary in vegetation, secondary in
fauna) '
Growth, of exotic invaders in wet meadows pland
communities (ie. purple loosestrife, bluegrass)
Loss of native fish species: 20 species have disappeared
since 1940's .
Introduced mosquito fish displaces native fish by
outcompeting them
Decline in mussel populations, limited to one principal
side channel with regular flow (high dieoff during drought
year of 1990)
Extensive periodic fish kills correlated with low flows in
late summer: 6-7 events every 10 years
Savidge & Currier, anc. 93
Savidge^ anc. 93
Sidle, anc. 93
Decline in mussel populations,
limited to one principal side channel
with regular flow (high dieoff
during drought year of 1990)
Currier, anc. 93
7
8
9
10
11
12
13
14
15
16
17
18
19
20
:21
22
23
"24
25
26
27
28
29
30
31
32
APPENDIX E. Excerpts from Nebraska Water Quality Report (NDEQ, 1992)
Designated Use Support (Existing "Conditions^ . ; "~ ;
"Adequate data and information were available to assess 276 stream miles or 45
percent of the basin's designated stream mileage for Aquatic Life Use Support during
1990 and 1991. Recreational use support was assessed for 158 of the 204 stream
miles assigned the use. Table C.I shows levels for beneficial use support based on
stream miles for the Middle Platte River Basin." (Ambient Water Body System
Report)
Table C. 1 . Middle Platte River Basin Summary of Beneficial Use Support during 1 QQft <] \ oo i
Recreation Class A
(203.8 miles) ,
Aquatic Life
(607.2 miles)
Coldwater Class A
(0 miles)
Coldwater Class B
(42.5 miles) >
Full
Support
0
0
27.5
Threatened
0
o - v
0
Partial
Support
80
0
15
Non
Support
98.2
' - ' -
0
0
Total
Assessment
178.2
(77%)
0 '
42.5
A10
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5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
Warmwater Class A
(344.3 miles)
Warmwater Class B
(220.4 miles)
Public Drinking Water
Supply (0 mile's)
Agricultural Water Supply
(607.2 miles)
Industrial Water Supply
(66.4 miles)
Overall Use Support
0
0
27.5
0
158.2
66.4
27.5
23.4
0 ,
23.4
0
0
0
13.4
146.9
63.0
224.9
0
0
0
225.0
0
0
0
0
0
0
98.2
170.3 .
63.0
275.8
(44%)
0
158.2
(26%)
66.4
(100%)
364.1
(60%)
Causes and Sources of Designated Use Impairment
Factors which prevented full support of recreational uses relate primarily, to impacts
from agricultural nonpbint sources. Minor impacts from domestic point sources and
urban nonpoint sources were also present. Partial support of the Aquatic Life use in
Warmwater A segments resulted primarily from agricultural nonpoint sources.
Forty-four percent of the major stream impacts in the Middle Platte Basin can be
ascribed to agricultural nonpoint sources, while 38 percent are impacted by stream
channelization. Eighteen percent have natural impacts. Minor impacts from
municipal and, industrial point sources and natural causes affected approximately 291
miles. The miles impacted by causes and sources within the Middle Platte River
Basin are listed in Tables C.2.'arid C.3.
Table C-2. Total Stream Miles Impacted by Various Cause Categories in the Middle Platte River
Basin. . '
Cause
NFS
Fecal Bacteria ,
Pesticides
Ammonia
Metals
Inorganics
Organic Enrichment/DO
Salinity/TDS/Chlorides
Flow Alteration
Major
44.51
120.59
Minor
42.32
25.42
43.04
44.61
70.03
t
All
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3
. 4
5
6
7
8
9
10'
11
12
13
14
15
16
17
18
19
20
21 .
,22
23
24
25
26
27
28
29
30
31
32
33 -'
34
35
36
37
38
39
Loss of Habitat . 5459
Unknown . 59.99
, ... , . ' - . ' "
Table C-3. Total Stream Miles Impacted by Various Source Categories in the Middle Platte River Basin
Source Category
Industrial Point Sources
Municipal Point Sources
Agriculture
Urban/Storm Runoff
Channelization
Natural .
Unknown ...
Major
140.55
120.59
59.99 .
Minor
65.60 .
70.03
154.87 .
Table C-4.- Water Quality-Based Limits - Water Quality LimitedSegments, 303(d) segments, TMDLs, will geta water
quality-based permit.. . . .
Segment #
MP 1-20000
, MP2- 10000
MP2- 10000
=^======
Stream
Platte River
Platte River (trib. to)
Platte River (ditch to)
===^===
Facility
Central City WWTP
Kearney #1 WWTP
Grand Island
WWTP
Comments
Expected to. exceed instream ammonia criteria based
on discharge concentrations reported in 1991
Expected to exceed instream ammonia criteria based
on discharge concentrations reported in 1991
Expected to exceed instream ammonia criteria based
on discharge concentrations reported in 199 1 '
A12
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1
2 . -. .
3 ' '
4 - ' ' .-.- . -
5
6
7 '..-.. . .
8 . '.-.'
9 ' . ,
10
11
12
13
14
15 .
16 . '
17
18 .
19 '
20 ,
21 * . . - '
22 ' -: / . .
23 - ..,.'
24 ' - ' .'....
25 APPENDIX F: Selection of Assessment Endpoints
26 . ' '..-'.
27 The process for the selection of endpoints was iterative and the result of several work
28 group meetings. The process consisted of four basic steps:
29 . .
30 Step L Identification of Reference Condition
31 To accomplish the goal of maintaining the 7 habitat types; (urban, agricultural,
32 riparian woodland, aquatic, sandbar, wetmeadow, and upland grassland) arid the
33 landscape in which they are embedded, a reference state towards which land
34 management must progress had to be determined. Pristine or presettlement condition
35 was rejected as the control habitat condition due to the extreme temporal variability
36 that characterizes the Middle Platte Watershed (not to mention the logistical
37 constraints on identifying th^s state). Therefore, those patches that best approach the
38 conditions described in this document (section 4.0, high quality habitat as determined
39 by the "best professional.judgement" of the habitat focus groups), will be used as the
40 reference condition for each habitat type. A key attribute that is used in determining
41 the reference habitat is the intrinsic value (where "value" includes, ecological,
42 economic, and aesthetic components) of a given patch within the landscape. Central
43 to the determination of "value" for a given habitat patch is the potential for the
A13
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. 1 protection and enhancement of the ecological integrity of the Middle Platte
2 , watershed. . -'- ' '. '
-3 - ..=.' " ''''"' . ' '
-.4 Step 2. Rating of Assessment Endpoints
5 A series of assessment and measurement endpoints were identified for each
6 ecological component (Appendix E and F). Each of these assessment endpoints were :
7 rated based on three criteria: susceptibility, societal value, and ecological relevance
8 (Suter, 1990). The value of the ratings were High (H), Moderate (M), or Low (L;
9 Appendix G). .
10 -
11 " Step 3. Selection of Assessment Endpoints .
12 Within the Middle Platte Watershed: the landscape mosaic, four habitat types (upland
13 grassland, wetmeadow, sandbar, and aquatic), and three functional groups of fauna
14 (breeding birds, migratory birds, and native fish) were chosen as final assessment '
15 endpoints. The landscape mosaic was chosen as an assessment endpoint because all
16 - or most of the qualities of the habitat and biotic endpoints of interest will be some
17 function of (or strongly related to) a healthy mosaic, or critical mix, of patch types at
18 the landscape level (Noss, 1990). The habitat and biotic endpoints were selected due
19 to their ratings for susceptibility, ecological relevance, and societal value and for their
20 overall importance in supporting ecological integrity in the landscape. Other potential
2-1 assessment endpoints (e.g. water quality and hydrology) remain in the analysis as
22 measurements to provide objective information about ecosystem conditions, however
23 the analysis of these additional indices is limited. " . '
24.' . !:--.,'.-;.. . . ''-.''. '.'...
25 SimA. Describing the Assessment Endpoints and Selecting Measurement Endpoints
26 Subgroups were organized around the ecosystem/habitat assessment endpoints
27 (aquatic, sandbary wetmeadow and the upland grassland "focus groups"). Objectives
28 were to reach agreements on the structure and composition of each critical habitat, the
29 ecological role of the key biota, and to identify potential measurement endpoints for
30 all assessment criteria. Potential measurements were chosen'for their high
3.1 susceptibility to loss of functioning, structure, and composition (from the impacts of
32 the major stressors) at the landscape, and ecosystem levels. Appendix xx contains the
33 potential list of measurements, which.could indicate the status of the assessment
34 endpoints. Appendix xx contains a list of available measurement endpoint datasets.
35,, Appendix xx lists identified needs for other datasets not available "
36 '.- .
37 .-. ' '. ' ; ,'-.."
38' . .. ' .-""' ..' V' ''-' '-.'.
39: , '. . . : ' : . ./' . ' *
40 .
4i '. ; . ' . _.-.
.42 - . ; . . .':..". - '
43 . ." : '' ".' . ." '
A14
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5
6
7
8.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
'30
31
32
APPENDIX G. Original Rankings of Proposed Assessment Endpoints
Workgroup ratings for susceptibility, societal value, and ecological relevance criteria
of proposed Middle Platte Assessment Endpoints based on Suter, 1990.
35
36
37,
38
39
40
41
IL
Rating of proposed middle Platte River Assessment Endpoints
Assessment Endpoints: Habitats
and Landscape patterns
Wetmeadows/ Wetlands
Sandbar / Herbaceous River
Island
Susceptibility
High
"High
Societal Value
High
High
Ecological .
Relevance
High
High
/ '
Data
Availability
High
High
A15
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6
7
8
9
10
11
12
13
; 14 .
"15
16
17
18
19
20
'"21.
22
23
24
25-
26
,27
28
29
30
31
32
33
.Aquatic (lotic, lentic,
backwater)
Riparian Shrub / Forest.
Upland Prairie Grassland / :
Shrub .'
Cropland '
High
Low ,
High
Low
High
Moderate
Moderate
High
High
Moderate
Moderate '
High
Moderate ,
Moderate
Moderate
High
Biota
Migratory Birds
Resident Birds.
Threatened / Endangered
Species .
Primary Producers
Aquatic Food Chain
Indigenous Amphibians
Indigenous Fish Species /
Populations
Sport Fish Species /
Populations !
Game Species
Susceptibility
High
Moderate
High
High
High
High
High .
Moderate
Moderate
Societal
Value
High
High
High
Low
Low
Moderate
Low
High
High.
Ecological-
Relevance
High
Moderate
High
High
High
High -
High
Moderate
Moderate
Data
Availability
High
Moderate
High
Low
Low
Low
Moderate
Moderate
Moderate
APPENDIX H. Proposed Ecological Values and Assessment: Assessment
Endpoints and Measurements for Four Primary Components of a Functioning and
Sustainable Middle Platte River System.
Component #1. Habitats and Landscape Patterns
Ecological Value: Maintenance, and where possible, enhancement of the mosaic
of habitats in the Middle Platte River System in order to support the diverse flora
and fauna dependent upon them while providing for existing recreational,
commercial, and agricultural uses. . . '
Assessment Endnoints
Al6
-------
Aquatic (lotic, lentic, backwater) (H,H,H)
Quantity: area (river miles)
Physical: sediment load; wetable surface
Chemical: water quality criteria
Biological: bacteriological (fecal); index of
biotic integrity'
(IBI); index of invertebrate
community integrity (ICI).
Sandbar/Herbaceous River Island (H,H,H)
Quantity: area of sandbar and vegetative
; cover
Physical: water depth, flow, flow
variability
Chemical: NA
Biological: vegetative coverage and type,
absence/presence of indicator
flora and/or fauna, community
measurements
Riparian Shrub/Forest (L,Mi,L)
Quantity: area '
Physical: NA
Chemical: NA
Biological: vegetative coverage and type,
absence/presence of indicator
flora and/or fauna, community
measurements
Wetmeadows (Other Wetlands) (H,H,H)
Quantity: area (acres)
Physical: antecedent moisture, ground
water depth
Chemical: NA
Biological: yegetative coverage and type,
absence/presence of indicator
flora and/or fauna, community
measurements
5
6
Prairie Grassland / Upland Woody Communities
(HMoH)
Quantity: area (acres)
Physical: NA
Chemical:- NA
Biological: (TBD)
Cropland (L,H,H)
Quantity: area (acres), production
volume
'Physical: _NA
Chemical: pesticide use
Biological: type of crops (%)
8
9
JO
11
12
* Rating for suseptibility, societal value, and ecological relevance H=high; Mo=Moderate; L=Low;
Mi=Mixed
A17
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4.
5
6
7
8
9
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11
12
13
14
15
16
'17'..'
18
19
20'.
21
22
23
24 ,
25
26
27
28,
29
30'
31
32
33
Component #2. Biota
Ecological Value: Maintenance, and where possible, enhancement of the
abundance and diversity of the living resources of special importance to the middle
Platte River System. '; '
Assessment Endnoints
Measurement Endnoints
Migratory Birds (H,H,H)
* aquatic (cranes, piping plover, least
tern, etc.) . ,
* terrestrial (songbirds) .
Breeding Birds (M,H,M)
* Red-tailed hawks, owls, falcons .:.
Threatened and Endangered Species
(H,H,H) .... ,
Primary Producers (H,L,H)
Aquatic Food Chain (H,L,H)
Amphibians Community (H,M,H)
Indigenous Fish Species or Populations
(H,L,H) . .
Sports Fishery (M,H,M) .
(including catfish)
Huntable Wildlife (M,H,M)
population counts and surveys (temporal
and seasonal, nesting success) -
population counts and surveys
actual counts (individuals) .
biotic index; periphyton
invertebrate community index
population counts (transect) abundance and
diversity surveys
fish'surveys .
estimated fish catch, including weight, age,
and condition; fish surveys
game take including weight, age,and
condition; population surveys, particularly
for game caught by trapping (huntable
wildlife associated with water)
Component #3a. Ecosystem Water Quality
Ecological Value: Maintenance, and where.possible, enhancement of the water
quality such that the water resources (surface and groundwater) of the Middle
Platte watershed support designated aquatic life uses while also supporting other
designated uses (e.g. drinking water, human health, agricultural etc.).
Assessment Endnoints
Measurement Endnoints
A18
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Surface water quality (M',H,H)
Physical: p'H, temperature, turbidity
Chemical: water quality criteria, Fish
advisories
Biological: bacterial criteria,
bioassessments
2
3
Groundwater quality (H,H,H)
Physical: NA
Chemical: water quality criteria; .
Pesticides: nitrates
Biological: bacterial criteria
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
'Component #3b: Ecosystem Hydrology
Ecological Value: Maintenance, and where possible, enhancement of the surface
and groundwater hydrology of the Middle Platte watershed in order to support
diverse flora and fauna dependent upon them while providing for existing
recreational, commercial, and agricultural use. '
[I Assessment Endpoints
Measurement Endpoints
26
27
Riverine hydrology (H,H,H)
Groundwater hydrology
(H,H,H)
Physical: flow volume, water depth,
seasonal variation
Chemical: NA
Biological: NA
Ground water level
Chemical: NA
Biological: NA
A19
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Figure ^."Platte River Basin
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Figure 4. Summary of Major Diversions from the Platte
Missouri River
Louisville 4.73
Elkhom River 0.88
.73 J)
1.16
. Loup River " 054 ^
Kearney Power Canal 0.06
Kearney Canal 0.08
Mean Annual Straamflow
Determined for Period of
Available Records
in Millions of Acre-Feet
Per Year
1.16
»
1JI7
River or Creek and
Mean Annual Flow
Canal and Mean
Annual Flow
QtyorTown
Calculated Flow
Cozad 0
0.35 Salt Creek
324 North Bend
O 1-14 Grand island
Q 1.17 Overton
Johnson Power Ganal
I.49 O
Thirty-mile, Gothenburg, Six-mile
Cozad, Orchard-Alfalfa and
Dawson Canals
-J
Jaffery Power Canal
056 Brady
Tri-County Canal
1.62
North Platte River
1.07
South Platte River
Figure 4. Mean Annual Streamflow along the Platte
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Draft - Do Not Cite or Quote
F-64
Figure -20. Sandhill Crane Staging Areas in the Platte River Valley
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Draft - Do Not Cite or Quote
F-66 '
Figure SQT Confirmed Sightings and Migration Corridors of the Whooping Crane
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Figure 5. Transportation network in the Middle Platte Watershed
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Figure 6. Land use in the Middle Platte Watershed
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Figure 27. Wetlands in the Cozad-Kearney reach of the Middle Platte Watershed
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figure 26. Wetlands in the Kearney-Grand Island reach of the Middle Platte Watershed
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