Marquette Chute: A Cooperative Project of the U.S. Army Corps of Engineers, U.S. Fish
and Wildlife Service, Illinois Department of Natural Resources, Missouri Conservation
Department, and the Long Term Resource Monitoring Program to Restore Habitat in
the Mississippi River

Marquette Chute is located between Upper Mississippi River (UMR) miles 47.0 and
53.0. It forms an indefinite boundary between the states of Missouri and Illinois. The
side channel supports important aquatic habitat for many obligate and commensurate
riverine organisms. Of the remaining side channels in the Middle Mississippi River
(MMR), Marquette Chute is generally believed to have one of the higher substrate and
depth diversities. From a fisheries standpoint, the side channel is very important
because federal and state listed species, including pallid sturgeon (Scaphirhynchus
albus), lake sturgeon (Acipenser fulvescens), sicklefin chub (Macrhybopsis meeki),
sturgeon chub (M. gelida), blue sucker (Cycleptus elongatus), and Ohio shrimp
(Macrobrachium ohione), have been captured in it.

Biologists, long recognizing the need to enhance side channel habitat in the MMR,
identified Marquette Chute for micro modeling in 1995. Micro modeling is physical
sediment modeling on an extremely small (micro) scale. The simulated
hydrographic/sediment response of any alluvial system, including detailed engineering
analysis, is conducted on a table top flume. The river banks in these models are
generally fixed. Micro modeling technology allows biologists and engineers to evaluate
a variety of in-stream environmental design alternatives and determine which have the
most positive effect on bed configuration (sediment transport response) and flow
patterns within the study area. The goal is to create desirable biological diversity while
ensuring a safe and reliable navigation channel.

Marquette Chute is an old mainstem channel of the Mississippi River. Because of the
position of the chute in relation to the river, the Mississippi attempts to recapture the
old channel. To ensure this doesn't happen and to divert sufficient water to maintain
navigation, the inlet to the side channel has been closed by an extensive rock dike
structure. Results of the micro modeling showed little could be done to improve aquatic
habitat over most of the upper 2/3 of the chute because so little water can be allowed to
flow through the channel (Davinroy et al. 1997). However, Open River Field Station
(ORFS) biologists have captured several fish species of concern immediately below the
inlet closing structure, where openings (herein referred to as "notches") have scoured
deep holes and deposited rare gravel bars. Blue suckers, river darters (Percina
shumardi), and other species with specific habitat requirements have been sampled in
these areas.

Realizing that such habitats are rare in the MMR, the U.S. Fish and Wildlife Service
(USFWS) secured special funding in the form of a grant for habitat enhancement work
in Marquette Chute. The USFWS grant was combined with funds from the U.S. Army
Corps of Engineers' (COE) Avoid and Minimize Program (A&M) and the design and
planning stages of the Marquette Chute habitat enhancement project began.

On August 25-27, 1998, a meeting was convened in conjunction with the St. Louis COE
annual dredge spoil placement boat trip, in which project alternatives for the Marquette
Chute work were discussed. Participants were interested in meeting two objectives: 1)
improve habitat diversity, and 2) experiment with COE equipment to carry out habitat
objectives. In the past, much of this kind of work was contracted out. It was decided the
M. V. Grandtower would be used to maneuver the work barge in lieu of the M. V.
Pathfinder because the latter was not as maneuverable and its operational costs are
higher.

One alternative discussed was to cut a deep notch above an existing notch where the
river was already creating a depression in the closing structure (Figure). The idea was
to enhance flows through the closing structure in an area where the river was naturally
doing it anyway. By cutting a deep notch similar to the natural notch (Figure), it was
hoped that gravel and cobble could be deposited along and downstream of the scour
hole. Another alternative was to notch the wingdam upstream of the existing notch
(Figure) to allow water to remove the sand plug filling the notch. The existing notch was
created in February 1998 by the COE to possibly aid in removing a small portion of a
sand bar and create more depth diversity in the chute. It was decided at the meeting an
on-site inspection was needed to determine if these proposals were feasible, and if not,
where a notch(es) could be placed to meet the objectives of the project.

On August 31, 1998, Dave Gordon (COE), Lesly Conaway (ORFS), and J. J. Frazier
(ORFS) met the crew of the M. V. Grandtower for an on-site inspection and evaluation
of project alternatives. The team made the following observations and
recommendations: 1. the wingdam (Figure) was too short to effectively notch and
probably would have only limited effect on the sand plug; and, 2. a series of shallow
notches would probably create more depth and substrate diversity than a single deep
notch. The decision was made to create a series of shallow notches based on a series
of bathymetry maps showing three scour holes that have apparently persisted over the
years. The scour holes were created by small natural notches in the closing structure.
The deepest notch produced the shallowest scour hole. Dave Gordon concluded the
increased head differential between the river elevation and the elevation of the river
behind the structure provided more energy to create deeper scour holes. Given this, a
plan was developed to create a series of notches of differing elevations by enhancing
existing natural notches in the closing structure. The idea was to create a "string of
pools", which may someday connect to each other downstream of the closing structure.
A series of seven notches were laid out by the team. Two notches were designed to
enhance about a half-acre, shallow pool located on the adjacent sand bar (Figure). The
intent was to increase the wetted edge of this seasonal, temporary habitat for wading
birds and provide more water for amphibians and reptiles.

Work began on September 1 and concluded on September 4, 1998. The river stage fell
from 22 feet to 17 feet (Cape Girardeau gauge) during this period. Early in the week,
additional areas were identified for notching, but low river levels impeded access to
some sites. At projects end, eight notches were cut in the closing structure (Figure and
Table). The crew of the M. V. Grandtower provided valuable input regarding logistics
and the work load given the equipment and time available.

A clam bucket was used to create notches in the closing structure. The crane operator
was able to grab rock and place it onto the existing structure instead of dragging rock
into the river. This prevented filling of deep water areas and may create a nozzle effect
through the newly created notches at appropriate river stages (in excess of 26 feet,
Cape Girardeau gage). In the February, 1998 project, a drag line was used to remove
rock, which had to be deposited in the river. The clam bucket was much more efficient
than the drag line, however, efficiency of the bucket declined sharply when attempts
were made to remove rock below the surface of the water. Hydraulic equipment not
currently available to the St. Louis COE is needed to efficiently remove rock from below
the water surface. Because the team removed rock from depression areas in the
closing structure, fewer rocks had to be displaced to create a notch at a desired
elevation. Work progressed quickly using this approach.

Funds for the project were made available through the St. Louis COE, Avoid & Minimize
Program and a grant by the U.S. Fish and Wildlife Service. The consulting on-site
engineer was Dave Gordon (St. Louis COE); consulting on-site biologist was Jenny
Frazier (ORFS). Lesly Conaway (ORFS), Bob Hrabik (ORFS), and Steve Dierker (St.
Louis COE) were also present throughout phases of the construction.

Literature Cited:

Davinroy, R. D., D. C. Gordon, and R. D. Hetrick. 1997. Sedimentation study of the
Mississippi River, Marquette Chute, hydraulic micro model investigation.
Technical Report M3, U.S. Army Corps of Engineers, St. Louis District,
Hydrologic and Hydraulics Branch, Applied River Engineering Center, St. Louis,
Mo. Final Report, December, 1997.

Jennifer J. Frazier and Robert A. Hrabik
Missouri Department of Conservation
Long Term Resource Monitoring Program
Open River Field Station

December, 1998
A synopsis on habitat enhancement work in, September 1998: