FLOOD04472

• County: Statewide
• Community: Nemaha County Nebraska
• Stream Name: Missouri River Miles 532.4-528.9
• Basin: Statewide
• Title: Langdon Bend Habitat Restoration/Preservation Project Volume 1
• Date: 6/1/1995
• Prepared For: US Army Corps of Engineers
• Prepared By: Greenhorne & O'Mara, Inc.
• Floodplain - Doc Type: Project

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According to Carter, et al. (1982), benthic densities and numbers of taxa were typically
lowest in June and increased in late summer and autumn. This was attributed to a relatively stable
river flow, higher water temperatures, and increased photoperiod. At other times the swift
current, high turbidity, and substrate instability of the main channel of the Missouri River
seriously limit the development of macro invertebrate populations. Major colonizers are restricted
to pile dikes, rip-rap, and a narrow zone near shore. Trichoptera, Ephemeroptera, and Diptera
inhabit the dikes and Chironomidae and Oligochaeta are commonly found in depositional areas
near shore (Carter, et al. 1982).

The periphyton of the channelized Missouri River is dominated by a combination of
diatoms, green algae, and blue-green algae. Bacillariophyta, Chlorophyta, and Cyanophyta are
dominant forms of periphyton in the river (Farrell and Tesar 1982). Seasonal patterns of
zooplankton abundance were measured by Repsys and Rogers (1982) in the vicinity of Fort
Calhoun and Cooper Nuclear Stations. Extensive studies of river biota have been conducted
throughout this stretch of the Missouri River to evaluate the effects of the two nuclear stations,
They found that the populations were characterized by relatively high microcrustacean densities
from late fall to spring, with reduced populations occurring during summer and early autumn,
Most of the zooplankton present in the lower portion of the river originate in the mainstem
reservoirs located in the upper portions of the Missouri River.

g. TerrestriallWetland Resources: The following infonnation was obtained through
interpretation of aerial photographs taken in April 1994 (scale 1: 12,(00), The infonnation was
verified and enhanced through a field investigation in January 1995. A Wetland Map is provided
as Exhibit 4. The wetland category discussed below includes portions of land included under
other resource categories; therefore, some overlap of acreage exists.

(1) Riparian Timber. Approximately 5 percent of the total acreage in Nemaha
County is forested (USDA 1985). The amount of forested acreage has steadily declined due to
the conversion of forest land to cropland. The decline in pioneer forests are due to the slow rate
of point bar fonnation in the rivers and the natural conversion of existing pioneer forest to forests
of later successional species. The largest tracts of forest land on the project site are located along
the Missouri River, There are two main forest cover types: oak-hickory and bottomland
hardwoods. The bottomland in the Onawa-Haynie-A1baton association supports the hackberry-
American elm - green ash and eastern cottonwood forest cover types. Eastern cottonwood, black
willow, and American sycamore dominate in areas close to the Missouri River,

Currently, approximately 176.5 acres (24 percent) of the project site is riparian timber.
Field reconnaissance indicated that these wooded areas are comprised of mature stands of
cottonwood, black willow, red maple, green ash, and sycamore. Several of the cottonwood trees
are over mature and losing their bark. The understory includes black willow, boxelder, red
maple, red mulberry, and hackberry. Roughleaf dogwood is also common in the understory of
the forested areas. A list of common and scientific names is included in Appendix A.

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