Long Term Resource Monitoring Program

Technical Report

 93-T003

An Aquatic Habitat Classification

System for the Upper

Mississippi River System 

This PDF file may appear different from the printed report

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May 1993
An Aquatic Habitat Classification System

for the Upper Mississippi River System

Daniel B. Wilcox

U.S. Fish and Wildlife Service

Environmental Management Technical Center

575 Lester Avenue

Onalaska, Wisconsin 54650

May 1993
This report is related to the efforts of the Ecological Research and

Evaluation Division, Environmental Management Technical Center.

At the time of publication of this report, Robert L. Delaney was

Program Manager, Barry W. Drazkowski was Deputy Program Manager, Dr.

John W. Barko was Technical Director, Dr. Ken Lubinski was Manager of

the Population and Community Ecology Group, and Terry D'Erchia was

report editor.

This report was developed with funding provided by the

Long Term Resource Monitoring Program.

The standard review procedure for Long Term

 Resource Monitoring Program Technical Reports includes

internal review by selected Environmental Management

Technical Center staff members, as well as review by

at least three external scientists competent

in the appropriate discipline(s).

Cover graphic

by Craig Nichols
v

Preface

The Long Term Resource Monitoring Program (LTRMP) was authorized

under the Water Resources Development Act of 1986 (Public Law 99-662)

as an element of the U.S. Army Corps of Engineers' Environmental

Management Program. The LTRMP is being implemented by the

Environmental Management Technical Center, an office of the U.S. Fish

and Wildlife Service, in cooperation with the five Upper Mississippi

River System states, Illinois, Iowa, Minnesota, Missouri, and

Wisconsin, with guidance and program responsibility provided by the

U.S. Army Corps of Engineers.

The mission of the LTRMP is to provide decision makers with

information to maintain the Upper Mississippi River System (UMRS) as

a viable large river ecosystem given its multiple-use character. The

long term goals of the program are to understand the system,

determine resource trends and impacts, develop management

alternatives, manage information, and develop useful products.

The aquatic habitat classification system described here was

initiated as part of Task PA(S)1: Classify Upper Mississippi River

System backwater areas according to geomorphological, hydrological

and biotic characteristics as described in the original Operating

Plan for the LTRMP (Rasmussen and Wlosinski 1988). The

classification system was meant to identify and define standard

categories of aquatic habitats for establishing subsequent research

and monitoring designs, and for creating selected map coverages in

the LTRMP geographic information system.

Modifications to this aquatic habitat classification system, if

necessary, will be based on data collected under strategies

associated with monitoring floodplain elevation, aquatic and

terrestrial vegetation, sediment composition, and aquatic and

floodplain habitat (USFWS 1992).

This report should be cited as:

Wilcox, D. B. 1993. An aquatic habitat classification system for

the Upper Mississippi River System. U.S. Fish and Wildlife

Service, Environmental Management Technical Center, Onalaska,

Wisconsin. EMTC 93-T003. 9 pp. + Appendix A.
vi

Abstract

A classification system for aquatic habitat in the Upper

Mississippi River System (UMRS) is needed for inventory, research,

impact assessment, and management purposes. The comprehensive system

of aquatic habitat classification proposed here has a hierarchical

structure to facilitate habitat mapping and inventory at different

spatial scales and varying levels of resolution. The classification

system is based on geomorphic features of large floodplain rivers,

constructed features of the UMRS, and physical and chemical

characteristics of aquatic habitat.
vii

Table of Contents

Page

Preface ............................. v

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

Table of Contents . . . . . . . . . . . . . . . . . . . . . . . . vii

List of Tables ........................ viii

List of Figures ........................ viii

Introduction .......................... 1

A Proposed Aquatic Habitat Classification for the UMRS ..... 3

Application ........................... 6

References ........................... 8

Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

General Definitions - Proposed Aquatic Habitat

Classification for the Upper Mississippi River System . A-1

Definitions - Aquatic Areas of the UMRS . . . . . . . . . . A-3
viii

List of Tables

Page

Table 1. Examples of conditions used to define aquatic habitat

types ........................... 5

Table 2. Vertical dimension of Upper Mississippi River

System aquatic habitat .............. 6

List of Figures

Figure 1. Upper Mississippi River System ............ 2

Figure 2. Aquatic areas of the Upper Mississippi River System . 4

Figure A-1. Example Upper Mississippi River System aquatic areas A-2

Figure A-2. Tributary delta lake and tributary channel . . . . . A-4

Figure A-3. Floodplain shallow aquatic areas . . . . . . . . . . A-5

Figure A-4. Lateral levee lake . . . . . . . . . . . . . . . . . A-6

Figure A-5. Scour channel lakes . . . . . . . . . . . . . . . . A-7

Figure A-6. Floodplain depression lake . . . . . . . . . . . . . A-8

Figure A-7. Artificial lakes . . . . . . . . . . . . . . . . . . A-9
Introduction

The Upper Mississippi River System (UMRS) includes the navigable

portions of the Mississippi River above the mouth of the Ohio River,

the Illinois River, and the lower reaches of the Minnesota, St.

Croix, Black, and Kaskaskia Rivers (Fig. 1). The UMRS upstream of

St. Louis, Missouri, has been canalized by a series of locks and dams

to maintain a minimum 2.74-m (9-ft) navigation channel. The UMRS

downstream of Lock and Dam 26 near St. Louis, Missouri, is

unimpounded but constrained by revetments, channel-training

structures, and levees. Channel-training structures, revetments,

levees, headwater reservoirs, and the navigation dams have imposed a

regulated flow regime and a set of anthropic aquatic habitat

conditions. However, despite these alterations, aquatic habitat in

the UMRS retains many characteristics of large floodplain rivers.

The UMRS, like other large river systems, contains a dynamic

mosaic of aquatic habitat. Measuring, mapping, and evaluating

aquatic habitat in a large river system is a challenging but

necessary effort for impact assessment, research, and management

purposes, and to allow stratification of sampling. There is also a

need to quantify different classes of aquatic habitat in computer

geographic information systems (GIS) for a variety of applications to

investigate habitat distributions at various spatial scales.

Nord (1967) and Sternberg (1971) distinguished large-scale

aquatic areas of the UMRS based on geomorphic and navigational

features of the river: main channel, channel borders, tailwaters,

side channels, river lakes and ponds, and sloughs. Archer et al.

(1980) and Carter et al. (1985) devised a similar classification

scheme for mapping Colorado River aquatic habitat, with more emphasis

on geomorphic features. Cobb and Clark (1980) and Cobb (1989)

developed an aquatic habitat classification system for the Lower

Mississippi River, describing aquatic zones (areas) based on

geomorphic and navigational features of the river. Leopold et al.

(1964) and Hutchinson (1957) classified river floodplain waterbodies

according to their geomorphic origins. Amoros et al. (1987)

considered the complex nature of fluvial systems and the need for

resolution at different spatial scales.

The Sternberg (1971) classification for the UMRS was designed to

describe fish habitat, to orient investigators to broad areas of

similar habitat, and to institute standard definitions. The

classification system met these objectives and has served UMRS

fisheries investigators well. This classification system is not

comprehensive, however, because it does not address smaller spatial

scales of aquatic habitat. For example, channel borders are

spatially large areas that extend the length of the river system,

containing natural banks, revetments, channel-training structures,

and a variety of depth, substrate, and current velocity conditions. 

Also, the names of aquatic areas in the Sternberg (1971)

classification are not widely used to describe floodplain

waterbodies.

Aquatic habitat in large rivers can be described at a largescale level by aquatic areas. Sternberg (1971), Archer (1980), and

Cobb and Clark (1980) all used similar descriptions of aquatic areas,

based primarily on large-scale geomorphic characteristics of

floodplain rivers.
2

Figure 1. Upper Mississippi River System
3

At finer scales of spatial resolution, aquatic habitat can be

further classified according to the conditions present. Habitat

conditions in running water can be defined using descriptors of water

temperature, dissolved gases, dissolved solids, suspended solids,

current velocity, turbulence, depth, substrate type, light, and cover

(Hynes 1970; Gorman and Karr 1978; Statzner et al. 1988). Habitat

patches in large rivers occur in a dynamic mosaic, influenced by

changes in river discharge and associated seasonal changes in

physical and water quality conditions. The appropriate scales for

ecological investigations of habitat patch and organism relationships

depend on the organism(s) and the problem(s) in question (Pringle et

al. 1988).

A Proposed Aquatic Habitat Classification for the UMRS

The classification system proposed here has a hierarchical

structure to allow habitat mapping and inventory at different spatial

scales and varying levels of resolution. At the first level or

largest spatial scale, UMRS aquatic habitat is classified into

aquatic areas (Fig. 2). Aquatic areas correspond to geomorphic and

constructed features of the river. Mapping units of aquatic areas

can be delineated, which remain spatially fixed until river and

floodplain geometry changes. These aquatic areas cannot be

considered habitat types, however, because they contain a wide range

of dynamic conditions within each category and mapping unit. 

Definitions for aquatic areas of the UMRS (Appendix A) correspond

closely to definitions of aquatic areas in the Lower Mississippi

River (Cobb and Clark 1980; Cobb 1989), but the UMRS classification

also includes features unique to the UMRS. The names and definitions

of different types of floodplain lakes follow Hutchinson (1957).

Some of the aquatic area boundary mapping definitions (Appendix

A) require information about floodplain and water surface elevation. 

Even without elevation data, most classes of aquatic areas can be

mapped from aerial photographs of the river floodplain using

provisional boundaries. When floodplain elevation and water surface

data become available, the mapping unit boundaries can be refined. 

For example, tertiary channels without emergent banks extend into

floodplain shallow aquatic areas. These smaller channels are not

apparent from aerial photographs, but they can be delineated using

bathymetric data.

At smaller spatial scales, aquatic habitat types can be

classified using combinations of aquatic habitat conditions. Aquatic

habitat conditions (Table 1) include physical and water quality

variables. Aquatic habitat types are user-defined, with habitat

conditions selected and ranges defined depending on the application. 

For example, an aquatic habitat type used by certain lotic fishes can

be defined as tailwater area, sand substrate, 2 to 5 m depth, and 10

to 50 cm/s current velocity. This habitat type is quite extensive in

tailwater areas of the UMRS at lower levels of river discharge, but

becomes more restricted at higher levels of river discharge as

current velocity and water depth increase.
4

Figure 2. Aquatic areas of the Upper Mississippi River System
5

Table 1. Examples of conditions used to define aquatic habitat types

Habitat conditions Condition ranges

Depth 0 - 0.5 m

 0.5 - 2.0 m

 2.0 - 5.0 m

 >5 m

Current

Velocity 0 - 10 cm/s

 10 - 100 cm/s

 >100 cm/s

Turbulence <500 Re (Reynold's number, laminar flow)

500 - 2000 Re (transitional)

 >2000 Re (turbulent)

Water temperature -1.0 - 0.0 EC (winter temperature ranges)

 0.0 - 2.0 EC

 2.0 - 5.0 EC

Dissolved oxygen 0 - 2.0 mg/L

 2.0 - 5.0 mg/L

 >5.0 mg/L

Suspended solids 0 - 10 mg/L

 10 - 25 mg/L

 25 - 100 mg/L

 100 - 300 mg/L

 >300 mg/L

Light 0 - 10 cm (1% light transmittance depth)

 10 - 50 cm

 50 - 100 cm

 100 - 200 cm

 >200 cm

Substrate type

Rock >100 mm (grain size)

Gravel 5 - 100 mm

Sand 0.074 - 5 mm

Silt + clay > 0.074 mm

Organic

Cover

Submersed aquatic

Emergent aquatic

Flooded terrestrial

Grasses/sedges

Brush

Forest

Overhanging trees

Overhanging bank

Rock

Built structures
6

The proposed aquatic habitat classification includes consideration

of the vertical dimension extending from the water surface into the

substrate (Table 2). A number of specialized communities exist on

the water surface, in the water column, on or in cover structures,

and on and in the substrate. Using vertical dimension

classification, habitat type occupied by caddisflies Hydropsychid

could be described as channel border, rock substrate surface, 0 to 1

m depth, and 50 to 100 cm/s current velocity.

Table 2. Vertical dimension of Upper Mississippi River System aquatic

habitat

_____________________________________________________________________

_

Vertical dimension features

_____________________________________________________________________

_

Water surface

Water column

Cover structure surface

Aquatic macrophytes

Rock

Coarse organic materials

Cover structure interior

Aquatic macrophytes

Coarse organic materials

Sediment surface

Sediment hyporheic zone

Deep sediment intertitial spaces

_____________________________________________________________________

_

Application

Application of the proposed aquatic habitat classification

involves mapping aquatic areas and more detailed investigations to

measure and to map the spatial and temporal occurrence of habitat

types. The floodplain of the UMRS covers approximately 728,000 ha,

and about 178,000 ha are normally aquatic habitat. Mapping of

aquatic areas can be accomplished using interpretation of aerial

photography. Aquatic area boundaries can be refined as bathymetric

and water surface elevation information becomes available. 

Mapping and analysis of the dynamic habitat conditions in the

UMRS require repeated spatial measurements of habitat conditions and

realistically may be done only for special investigations covering 
7

limited areas. Given the spatial complexity and rapidly changing

habitat conditions in the UMRS, these efforts will be greatly aided

by remote sensing, hydraulic modeling, and computer GIS technologies.
8

References

Amoros, C., A. L. Roux, J. L. Reygrobellet, J. P. Bravard, and G.

Patou. 1987. A method for applied ecological studies of fluvial

hydrosystems. Regulated Rivers 1:17-36.

Archer, D. L., H. Tyus, and R. Valdez. 1980. Field methodologies of

the Fish and Wildlife Service's Colorado River Fisheries Project. 

Trans. Bonneville Chapter American Fisheries Society 13-36.

Carter, J. G., R. A. Valdez, R. J. Ryel, and V. A. Lamarra. 1985. 

Fisheries habitat dynamics in the Upper Colorado River. Journal

of Freshwater Ecology 3(2):249-264.

Cobb, S. P. 1989. Lower Mississippi River aquatic habitat

classification: Channel environment. U.S. Army Engineers Lower

Mississippi Valley Division, Vicksburg, Mississippi.

Cobb, S. P., and J. R. Clark. 1980. Aquatic habitat studies of the

Lower Mississippi River, river miles 480-530. Report 2, Aquatic

habitat mapping: Miscellaneous Paper E-80-1. U.S. Army Engineer

Waterways Experiment Station, Vicksburg, Mississippi.

Gorman, O. T., and J. R. Karr. 1978. Habitat structure and stream

fish communities. Ecology 59(3):507-515. 

Hutchinson, G. E. 1957. A treatise on limnology. Volume 1. 

Geography, physics, and chemistry. John Wiley and Sons, New York.

Hynes, H. B. N. 1970. The ecology of running waters. University of

Toronto Press. 555 pp.

Leopold, L., M. G. Wolman, and J. P. Miller. 1964. Fluvial

processes in geomorphology. W. H. Freeman, San Francisco.

Nord, R. C. 1967. A compendium of fishery information on the Upper

Mississippi River. Upper Mississippi River Conservation

Committee, Sec. Publication. 238 pp.

Pringle, C. M., R. J. Naiman, G. Bretschko, J. R. Karr, M. W. Oswood,

J. R. Webster, R. L. Welcomme, and M. J. Winterbourn. 1988. 

Patch dynamics in lotic systems: the stream as a mosaic. Journal

of the North American Benthological Society 7(4):503-524.

Rasmussen, J. L., and J. H. Wlosinski. 1988. Operating Plan of the

Long Term Resource Monitoring Program for the Upper Mississippi

River System. U.S. Fish and Wildlife Service, Environmental

Management Technical Center, Onalaska, Wisconsin, January 1988. 

EMTC 88-01. 55 pp. (NTIS # PB88 169669/AS)
9

Statzner, B., J. A. Gore, and V. H. Resh. 1988. Hydraulic stream

ecology: Observed patterns and potential applications. Journal

of the North American Benthological Society 7(4):307-360.

Sternberg, R. B. 1971. Upper Mississippi River habitat

classification survey, Hastings, Minnesota, to Alton, Illinois. 

Upper Mississippi River Conservation Committee, Fish Technical

Section.

U.S. Fish and Wildlife Service. 1992. Operating Plan for the Long

Term Resource Monitoring Program for the Upper Mississippi River

System. Environmental Management Technical Center, Onalaska,

Wisconsin, August 1992. EMTC 91-P002. 183 pp.
A-1

Appendix A

General Definitions - Proposed Aquatic Habitat

Classification for the Upper Mississippi River System

Reference River Discharge

The reference river discharge is the discharge level exceeded

50% of the time at point of interest.

Reference Water Surface

The reference water surface is the water surface elevation

profile associated with the reference river discharge.

Aquatic - Floodplain Terrestrial

A distinction is made between floodplain areas that are normally

aquatic and areas that are normally terrestrial at the reference

discharge level. At times of higher river discharge, more of the

floodplain is inundated and becomes aquatic habitat. Above the

reference discharge level, portions of the floodplain that are

normally terrestrial can be described according to their elevation,

frequency, and duration of inundation.

Channel - Backwater

A distinction is made between channel areas and off-channel or

backwater areas.

Channels. Channels in the Upper Mississippi River System (UMRS)

include the main channel, secondary and tertiary channels, tributary

channels, and excavated channels (Fig. A-1). Within the main channel

(and some secondary channels) are the designated navigation channel,

sandbar, channel border, and tailwater areas. Within channel border

areas are natural bank areas and areas associated with channeltraining structures.

Backwaters. Backwaters are areas of the UMRS that are beyond

the banks of the main and secondary channels. Backwaters include a

variety of alluvial floodplain waterbodies. Tertiary and smaller

tributary channels are included in backwater areas.

Contiguous, isolated. A distinction is made between contiguous

(connected by surface flow with the main channel) and isolated

backwaters.
A-2

Figure A-1. Example Upper Mississippi River System aquatic areas
A-3

Vertical Dimension

Depending on study needs, aquatic habitat in the UMRS can be

defined according to vertical spatial categories. Within aquatic

areas are the water surface, the water column, the surfaces of cover

structures such as aquatic macrophytes, rocks, and woody debris, the

interior of cover structures, the sediment surface, the hyporheic

zone within the sediment, and the deeper sediment.

Aquatic Areas

Aquatic areas are spatially large areas of somewhat similar

aquatic habitat defined according to geomorphic and navigational

features of the river (Fig. 2, p. 4).

Habitat Conditions

Habitat conditions are physical and chemical variables that

occur in aquatic habitat (Table 1, p. 5).

Habitat Types

Habitat types are defined as needed for the application, using

aquatic area and some combination of habitat conditions. No formal

classification of aquatic habitat types is proposed. Habitat type

definitions can be developed according to the needs of different

investigations.

Definitions - Aquatic Areas of the UMRS

The following proposed definitions of UMRS aquatic areas are

provided in conjunction with Figure 2 (p. 4) and examples shown in

Figures A-1 to A-7. Boundary definitions are provided for mapping

purposes.

Main Channel

The main channel conveys the majority of the river discharge and

in most reaches includes the navigation channel (Fig. A-1). 

Boundaries of the main channel are the apparent shorelines (the

land/water boundaries visible from aerial photographs taken at the

reference discharge level), straight lines across the mouths of

secondary, tributary, and tertiary channels, and along the top of

inundated portions of the natural bank line.

Navigation Channel

The navigation channel is the designated navigation corridor

marked by channel buoys (Fig. A-1). In reaches where buoys are not

used, the centerline of the navigation channel is defined by lights

and daymarks on shore that pilots use for navigation. The navigation

channel on most of the UMRS is 91.4 m (300 ft) wide in straight

reaches and 152.4 m (500 ft) wide in bends. The navigation channels

in the upper pools of the UMRS and tributary waterways are narrower. 

The prescribed width and depth of at least 9 ft (2.6 m) are
A-4

Figure A-2. Tributary delta lake and tributary channel
A-5

Figure A-3. Floodplain shallow aquatic areas
A-6

Figure A-4. Lateral levee lake
A-7

Figure A-5. Scour channel lakes
A-8

Figure A-6. Floodplain depression lake
A-9

Figure A-7. Artificial lakes
A-10

maintained by the navigation dams and by dredging where necessary. 

The navigation channel extends through the locks at each lock and

dam. The navigation channel is usually in the main channel but in

some reaches, it is located in secondary channels.

Tailwaters

Tailwaters are the areas downstream of the navigation dams with

deep scour holes, high velocity, and turbulent flow. Boundaries of

tailwater areas are the navigation dam upstream, the apparent

shorelines, and a straight line across the channel 500 m downstream

of the dam.

Channel Border

Channel borders are the areas between the navigation channel and

the river bank (Fig. A-1). Boundaries of channel border areas are

the apparent shorelines, the navigation channel buoy line, straight

lines across the mouths of secondary and tertiary channels, and the

inundated portions of the natural bank line.

Wing Dam

Wing dams are stone and brush channel-training structures that

extend laterally into the main and secondary channels to concentrate

flow into the navigation channel (Fig. A-1). The boundaries of wing

dam areas are defined by proximity to wing dam structures. The

landward boundaries are the apparent shorelines and inundated

portions of the natural bank line. The upstream and downstream

boundaries of wing dam areas are parallel to and 50 m from the wing

dam structures. The riverward boundaries are perpendicular to the

riverward end of the wing dams.

Closing Dam

Closing dams are stone and brush channel-training structures

that were built across channels to concentrate flow into the

navigation channel (Fig. A-1). Boundaries of closing dam areas are

parallel to and 50 m upstream and downstream of the structures. 

Where closing dams are close to the main channel border, the upstream

boundary is across the mouth of the channel. The lateral boundaries

are the apparent shorelines of the channel.

Revetted Bank

Revetted banks are the armored shorelines of the main and

secondary channels (Fig. A-1). Revetment on the UMRS is rock riprap

or articulated concrete mats. Shorelines with concrete or steel

bulkheads or paved levees are included in this category. In some

locations, bank revetment is no longer connected to shore. 

Boundaries of revetted bank areas are the apparent shoreline, the

upstream and downstream limits of the revetment, and a line

riverward, parallel to and 15 m from the apparent shoreline. For

revetments that are no longer connected to shore, the shoreward

boundary of revetted bank areas is a line parallel to and 15 m from

the top of the remaining revetment material.
A-11

Unstructured Channel Border

Unstructured channel border areas are areas without revetments

or other channel-training structures. Boundaries of the unstructured

channel border areas are the apparent shoreline, the upstream and

downstream limits of other channel border areas, the downstream

limits of tailwater areas, and indundated portions of the natural

bank line.

Depending on the application, unstructured channel border areas

can be further classified according to depth gradient and geomorphic

feature (point bar, inside bend, etc.).

Secondary Channel

Secondary channels are large channels that carry less flow than

the main channel (Fig. A-1). In some reaches, the navigation channel

is located in secondary channels. Boundaries of secondary channel

areas are the apparent shorelines, straight lines across the mouths

of tertiary channels, and straight lines at the upstream and

downstream limits of the apparent shorelines where secondary channels

connect with the main channel.

Sandbar

Sandbars are flat-sloped areas within the main and secondary

channels that are characterized by sand substrate (Fig. A-1). 

Sandbars have side slopes of less than 1V:6.67H, are completely

submerged at the 10% exceedence frequency discharge level, and are

not connected to shore at the reference discharge level. Portions of

sandbar zones emergent at the reference river discharge are

unvegetated. Sandbar boundaries are the 2-m depth contours at the

reference river discharge level and the apparent shoreline or

boundaries of rock structure areas.

Tertiary Channel

Tertiary channels are small channels #30 m wide (Fig. A-1). The

lateral boundaries of tertiary channels are the apparent shorelines

or the inundated natural bank lines. The upstream and downstream

limits of tertiary channels are straight lines between the upstream

and downstream limits of the apparent shorelines, or where the

inundated natural bank lines merge with the surrounding bottom.

Tributary Channel

Tributary channels are channels of tributary streams and rivers

(Fig. A-2). The landward boundary is the line where the tributary

crosses the study area boundary. The lateral boundaries are the

apparent shorelines and any inundated natural bank lines. The

riverward limit of a tributary channel is a line drawn across the

downstream limits of the apparent shoreline or where the inundated

natural bank lines of tributary channels merge with the surrounding

bottom.
A-12

Excavated Channel

Excavated channels are constructed channels with flowing water.

Contiguous or Isolated

Contiguous means hydraulically connected by surface gravity flow

at reference river discharge. For mapping purposes, contiguous means

having apparent surface water connection with the rest of the river. 

Isolated means having no hydraulic connection by surface gravity flow

at reference river discharge. For mapping purposes, isolated means

having no apparent surface water connection with the rest of the

river.

Floodplain Shallow Aquatic

Floodplain shallow aquatic areas are portions of the floodplain

inundated by the navigation dams that are not part of any channels or

floodplain lakes (Fig. A-3). Floodplain shallow aquatic areas

contain a mosaic of open water and emergent vegetation interspersed

among islands. The boundaries of these areas are defined by the

apparent shorelines and by other aquatic areas. Boundaries of

floodplain shallow aquatic areas are often irregular. Where

floodplain shallow aquatic areas grade into impounded areas, the

boundaries will be lines connecting the downstream points of islands

or peninsulas across the floodplain. Tertiary and smaller tributary

channels flow through floodplain shallow aquatic areas, but the

boundaries (inundated bank lines) of most of these channels can be

distinguished only with bathymetric information.

Impounded

Impounded areas are large, mostly open water areas located in

the downstream portions of the navigation pools (Fig. A-3). The

downstream boundaries of impounded areas are the navigation dam and

connecting dikes. Landward boundaries are the apparent shorelines or

the boundaries of other aquatic areas. Upstream boundaries are with

islands and floodplain shallow aquatic zones. Riverward boundaries

are channel border zones.

Floodplain Lake

Floodplain lakes are distinct lakes formed by fluvial processes

or are artificial (excavated or impounded).

Abandoned Channel Lake

Abandoned channel lakes are oxbow lakes formed by meander

cutoffs, lakes formed by point bar cutoffs, and lakes formed by

avulsion (a major shift in channel course) (Fig. A-1). Boundaries

are the apparent shorelines. The downstream boundary for contiguous

abandoned channel lakes is a line that is a continuation of the

apparent shoreline of the lake. Abandoned channel lakes vary greatly

in size. The shape of most abandoned channel lakes reveals their

origins as former channels.
A-13

Tributary Delta Lake

Tributary delta lakes are formed by the tributary deltas

impounding all or part of the floodplain upstream of the mouth of the

tributary (Fig. A-2). Boundaries are the apparent shorelines. For

contiguous tributary delta lakes, the riverward boundary is where the

(usually downstream) end of the lake joins a channel. The boundary

is a line that is a continuation of the apparent shoreline of the

channel.

Lateral Levee Lake

Lateral levee lakes are lakes formed by the impounding effect of

natural riverbank levees (Fig. A-4). This type of lake is formed

between the natural levee and the high ground that defines the edge

of the floodplain of the river. Lateral levee lakes are also formed

where natural levees impound tributary streams. Boundaries are the

apparent shorelines and the boundaries of other more clearly

delineated aquatic zones. On lakes formed at the mouth of tributary

streams, the upstream boundary is the boundary of the study area.

Scour Channel Lake

Scour channel lakes are formed by the scouring of point bar

swales during high flows (Fig. A-5). Scour channel lakes are

generally small and crescent-shaped. Most of these aquatic areas are

isolated. Boundaries are the apparent shorelines. Where contiguous,

the connecting boundary is a line across the downstream limit of the

apparent shorelines.

Floodplain Depression Lake

Floodplain depression lakes are generally large, shallow water

bodies formed by uneven aggradation of sediment on floodplains during

floods (Figs. A-6 and A-7). This type of lake has even shorelines

(limited shoreline development) and a shallow basin of even depth. 

Most of these lakes are larger than 100 ha. Boundaries are the

apparent shorelines. Where contiguous, the connecting boundary is a

line across the limits of the apparent shorelines.

Borrow Pit

Borrow pits are water bodies formed where material was excavated

for levee or dike construction. The boundaries are the apparent

shorelines or the limits of excavation. Most borrow pits are

parallel and immediately adjacent to dikes or levees.

Artificial Lake

These aquatic areas are created by dikes or levees (not the main

navigation dams and dike systems) or by excavation (Fig. A-7). The

boundaries of artificial lakes are the apparent shorelines, and where

contiguous, the connecting boundary is a line across the limits of

the apparent shorelines.
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VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, D.C. 20503

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE

May 1993

3. REPORT TYPE AND DATES COVERED

4. TITLE AND SUBTITLE

An Aquatic Habitat Classification System for the Upper Mississippi River System

5. FUNDING NUMBERS

6. AUTHOR(S)

Dan Wilcox

7. PERFORMING ORGANIZATION NAME AND ADDRESS

U.S. Fish and Wildlife Service 

Environmental Management Technical Center

575 Lester Avenue

Onalaska, Wisconsin 54650

8. PERFORMING ORGANIZATION

 REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

U.S. Fish and Wildlife Service 

Environmental Management Technical Center

575 Lester Avenue

Onalaska, Wisconsin 54650

10. SPONSORING/MONITORING

 AGENCY REPORT NUMBER

93-T003

11. SUPPLEMENTARY NOTES

12a. DISTRIBUTION/AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

A classification system for aquatic habitat in the Upper Mississippi River System (UMRS) is needed for inventory, research, impact assessment, and management purposes. The comprehensive

system of aquatic habitat classification proposed here has a hierarchical structure to facilitate habitat mapping and inventory at different spatial scales and varying levels of resolution. The

classification system is based on geomorphic features of large floodplain rivers, constructed features of the UMRS, and physical and chemical characteristics of aquatic habitat.

14. SUBJECT TERMS

aquatic habitat, classification, Upper Mississippi River, Illinois River, geomorphology 

15. NUMBER OF PAGES

9 pp. + Appendix A

16. PRICE CODE

17. SECURITY CLASSIFICATION

 OF REPORT

18. SECURITY CLASSIFICATION

 OF THIS PAGE

19. SECURITY CLASSIFICATION

 OF ABSTRACT

20. LIMITATION OF ABSTRACT
The Long Term Resource Monitoring Program (LTRMP) for the Upper

Mississippi River System was authorized under the Water Resources

Development Act of 1986 as an element of the Environmental

Management Program. The mission of the LTRMP is to provide river

managers with information to maintain the Upper Mississippi River

System as a viable large river ecosystem given its multiple-use character.

The LTRMP is a cooperative effort by the U.S. Fish and Wildlife Service,

the U.S. Army Corps of Engineers, and the states of Illinois, Iowa,

Minnesota, Missouri, and Wisconsin.