7427

• UCREFRP Catalog Number: 7427
• Author: Hesse, L. W., G. R. Chaffin and J. Brabander
• Title: Missouri River Mitigation
• USFW Year: 1989
• USFW - Doc Type: A System Approach
• Copyright Material: YES

r"hll (f'k~~l' ,'l .11. l'Jil6). Nillin' wg-
Cl.llioj) has LX'Cll rcpl.1\:cd wilh ww-
crop a~ricullurc, which in turn has
nccessitated the construction of thou-
sands of small and moderate-sizcd dams
to abate the downstream InJvement of
soils (sediment) from the basin. Flood
control measures (i.e., upstream struc-
tures and channelization), together with
loss of native vegetative cover, un-
doubtedly have interrupted the essen.
tial movement of dissolved and sus-
pended organic malter which forms
the basis of ecosystem productivity.
The ecology of the Missouri River,
like other large rivers in this country
and around the world, has been studied
extensively. The U.S. Fish and Wildlife
Service (1985) lists over 600 references
in a Missouri River bibliography. How-
ever, because stream ecology is such a
young science, and because there was
no coordinated effort to achieve an
understanding of integrated stream bi-
ology in the Missouri River basin prior
to or during implementation of devel-
opment projects, the consequences of
previous alterations are just now being
recognized. Hynes (1972) and Petts
(1984) presented sound reasons for be-
lieving that the biota within this river
system are still changing as a result of
these alterations. Demand for Missouri
River water, both for irrigation within
the basin and for transfer to other
drainage basins, may deplete the flow
volume within the river and further
threaten the continued existence of a
variety of resident and migratory native
fish and wildlife species.

Water Resources
Development Act
of 1986

The mitigation package authorized
in October 1986 by the Water Resources
Development Act (Public Law 99-662)
would result in the acquisition and
management of 12,100 hectares (29,900
acres) of aquatic. wetland, and terres-
trial habitats along the river. This rep-
resents only 6.3% of the habitat lost in
the original floodplain from Sioux City
to the mouth of the Missouri River. By
comparison, the mitigation recommen-
dations presented by the U.S. Fish and
Wildlife Service (1980) called for ac-
quisition of 47,350 hectares (117,000
acres) or 24.7% of the area of habitat
losses attributable to the project. The

12

authorized kder.ll funding Ie,'cl for
miligillion of fish ilnd wildlife r,'soure,'
losses in Missouri, KilnSils, 101\'.1, ilnJ
Nebrask<1 is S51. I} million.
The authorized mitigiltion package
fails, however, to address the impact
of impounding one-third of the river
in the upper reaches (which inundated
habitat, impeded downstream trans-
port of organic material and nutrients,
and prevented upstream migration of
fish); the impoundment and channel-
ization of at least 95 tributary streams
(Hesse 1987); or the impact of altering
the hydrologic cycle through the use
of large flood-control storage capabil-
ities. The importance of each of these
areas of impact to large river systems
has been discussed extensively by Pelts
(1984) and Welcomme (1985). The en-
abling legislation directs the Secretary
of the Army to ". . . study the need
for additional measures for mitigation
of losses of aquatic and terrestrial hab-
itat caused by such a project and . . .
report to Congress within three years
after the date of enactment of this Act,
on the results of such study and any
recommendations for additional mea-
sures needed for mitigation of such
losses." A most important aspect of
the authorized plan is the recognition
that restoration of this ecosystem
should be viewed as a long-term goal
rather than a short-term objective with
a finite ending point. This recognition
characterizes accurately the continuing
nature of impacts and the evolving
concerns for protection and restoration
of natural systems. The primary goal
of a long-term mitigation plan should
include the gradual return of floodplain
functions to the river over an extended
time period.

System Mitigation:

Objectives,

Site Locations,

Construction,

Management, and Costs

Successful mitigation for lost Mis-
souri River aquatic, wetland, and ter-
restrial resources requires an ecosys-
tem approach. An adequate mitigation
plan must recognize that the degree of
Success will depend on the extent to
which natural channel and floodplain
morphological features (e.g., chutes,
oxbows, sandbars, slackwater vege-
tated areas, terrestrial grassland and

fore5t,'colypcsl arc re-l'sl.lbIISill'c1 Till'
pfl'sent llIitig,ltiol1 pl.lI1 pnl\'ldl'~ Ill(
restoration of only il 5111.111 tr,ll11l111 uf
these feiltures as thev l'xisll'd .il till'
time the project was initialed.
Objectives for Missouri River miti-
gation are as follows:
1. Recovery of some of the structural
diversity (e.g., chutes, oxbows, s.lnd-
bars, vegetated backwater areas, and
non-agricultural vegetated areas on the
floodplain) of the pre-control Missouri
River ecosystem;
2. Re-establishment of native terres-
trial and wetland vegetation along the
channel and on the floodplain, includ-
ing native prairie, wet meadow, deci-
duous forest, sandbar successional
plant communities and vegetated is-
lands;
3. Restructured reservoir releases
timed to coincide with normal climatic
conditions in the basin, but reduced in
magnitude to continue to achieve the
benefits of flood control;
4. Development of either a fish lift
(elevator) or a bypass channel for main-
stem and tributary dams; and
5. Implementation of measures to cor-
rect the degradation/aggradation im-
balance which exists throughout the
channelized portion of the river and in
unchannelized portions isolated be-
tween the mainstem dams.
These measures will bc expensive
and some may be difficult to achie"e
from an engineering sense or a political
sense. In any case it is not our desire
to write Nebraska policy; instead, our
objectives must be viewed as the correct
approach from a biological perspective.
Table 1 lists initial sites proposed for
restoration in Nebraska. The estimated
costs show that system mitigation does
not have to be extremely expensive. In
fact, land acquisition will be the greiltest
cost; actual construction might be as
simple as removing a rock dike. Our
approach would emphasize good co-
operative relationships with floodplain
landowners. Therefore, land should
not be condemned to achieve acquisi-
tion; rather, the use of easements as
well as fee-title acquisition from willing
sellers should be explored. Education
programs should be developed to assist
landowners to recognize the value of
non-conventional uses of these bottom-
lands.
System mitigation would include re-
covery of old oxbow lakes cu t off by
channelization. Higher spring flows in

Fisheries, Vol. 14, No. ]