Long Term Resource Monitoring Program

Program Report

98-P007

1993 Annual Status Report

A Summary of Aquatic Vegetation Monitoring at

Selected Locations in Pools 4, 8, 13, and 26 and

La Grange Pool of the Upper Mississippi River System

July 1998
The Environmental Management Technical Center issues LTRMP Program Reports

to provide Long Term Resource Monitoring Program partners

with programmatic documentation, procedures manuals, and annual status reports.

Environmental Management

Technical Center

CENTER DIRECTOR

Robert L. Delaney

APPLIED RIVER SCIENCE

ACTING DIRECTOR

Ken Lubinski

PROGRAM OPERATIONS

ACTING DIRECTOR

Linda Leake

REPORT EDITOR

Jerry Cox

Cover graphic by Mi Ae Lipe-Butterbrodt

Mention of trade names or commercial products does not constitute endorsement

or recommendation for use by the U.S. Geological Survey, U.S. Department of the Interior.

Printed on recycled paper 
1993 Annual Status Report

A Summary of Aquatic Vegetation Monitoring at

Selected Locations in Pools 4, 8, 13, and 26 and 

La Grange Pool of the Upper Mississippi River System

by

Sara Rogers

U.S. Geological Survey

Environmental Management Technical Center

575 Lester Avenue

Onalaska, Wisconsin 54650

Theresa Blackburn

Iowa Department of Natural Resources

Mississippi River Monitoring Station

206 Rose Street

Bellevue, Iowa 52031

Kris Kruse

Minnesota Department of Natural Resources

1801 South Oak Street

Lake City, Minnesota 55041

Heidi Langrehr

Wisconsin Department of Natural Resources

Onalaska Field Station

575 Lester Avenue

Onalaska, Wisconsin 54650

John Nelson and Andrew Spink

Illinois Natural History Survey

Havana Field Station

704 N. Schrader Avenue

Havana, Illinois 62644

July 1998
Suggested citation:

Rogers, S., T. Blackburn, K. Kruse, H. Langrehr, J. Nelson, and A. Spink. 1998. 1993 annual status report: A summary of

aquatic vegetation monitoring at selected locations in Pools 4, 8, 13, and 26 and La Grange Pool of the Upper Mississippi

River System. U.S. Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, July 1998.

LTRMP 98-P007. 22 pp. + Appendixes A–B

Additional copies of this report may be obtained from the National Technical Information Service, 5285 Port Royal Road,

Springfield, VA 22161 (1-800-553-6847 or 703-487-4650). Also available to registered users from the Defense Technical

Information Center, Attn: Help Desk, 8725 Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or

703-767-9050).
iii

Contents

Page

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

Abstract ........................................................................ 1

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

Study Areas ..................................................................... 2

Methods ........................................................................ 6

Transect Sampling ............................................................. 6

Environmental Factors .......................................................... 9

Statistical Analysis ............................................................. 9

Informal Surveys ............................................................. 10

Results ........................................................................ 10

All Pools .................................................................... 10

Water Depths and Substrates .................................................... 12

Pool 4 ...................................................................... 12

Pool 8 ...................................................................... 15

Pool 13 .................................................................... 17

Pool 26 ..................................................................... 19

La Grange Pool ............................................................... 20

Acknowledgments ............................................................... 22

References ..................................................................... 22

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

Appendix B ................................................................... B-1

Tables

Table 1. Key features of the floodplain and aquatic area compositions of the five Mississippi and

Illinois River study reaches monitored for vegetation in 1993 for the Long Term Resource

Monitoring Program ...................................................... 4

Table 2. Submersed and floating-leaved aquatic vegetation most likely to be found in the area covered

by the Long Term Resource Monitoring Program, arranged alphabetically by common name

within family ........................................................... 8

Table 3. Frequencies and relative frequencies (%) of species in Pools 4, 8, 13, and 26 of the Upper

Mississippi River and La Grange Pool (LG) of the Illinois River in 1993 ............ 11
iv

Table 4. Proportion of sites with submersed aquatic vegetation to total number of sites sampled at

transect locations during the 1993 spring and summer sampling periods ............. 12

Table 5. Mean depths of submersed aquatic vegetation along sampling transects in Pools 4, 8, 13,

and 26 of the Upper Mississippi River and La Grange Pool of the Illinois River during the

1993 spring and summer sampling periods ................................... 12

Table 6. Relative presence of (%) substrate types along transects containing submersed aquatic

vegetation during the 1993 spring and summer sampling periods .................. 13

Table 7. Frequencies and relative frequencies (%) of species in Pool 4 during the 1993 spring and

summer sampling periods ................................................ 13

Table 8. Locations in Pool 4 where species were present during the 1993 spring and summer

sampling periods ....................................................... 14

Table 9. Frequencies and relative frequencies (%) of species in Pool 8 during the 1993 spring and

summer sampling periods ................................................ 16

Table 10. Locations in Pool 8 where species were present during the 1993 spring and summer

sampling periods ....................................................... 16

Table 11. Frequencies and relative frequencies (%) of species in Pool 13 during the 1993 spring and

summer sampling periods ................................................ 18

Table 12. Locations in Pool 13 where species were present during the 1993 spring and summer

sampling periods ....................................................... 18

Table 13. Frequencies and relative frequencies (%) of species in Pool 26 during the 1993 spring and

summer sampling periods ................................................ 19

Table 14. Locations in Pool 26 where species were present during the 1993 spring and summer

sampling periods ....................................................... 20

Table 15. Frequencies and relative frequencies (%) of species in La Grange Pool, Illinois River,

during the 1993 spring and summer sampling periods ........................... 20

Table 16. Locations in La Grange Pool, Illinois River, where species were present during the 1993

spring and summer sampling periods ........................................ 21

Figures

Figure 1. Main stem of the Upper Mississippi River System with the study reaches used in the

Long Term Resource Monitoring Program submersed vegetation surveys of 1993 ...... 3

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program ................ 4
v

Figure 3. Pool 8, Upper Mississippi River, transect locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program ................ 5

Figure 4. Pool 13, Upper Mississippi River, transect locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program ................ 5

Figure 5. Pool 26, Upper Mississippi River, transect locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program ................ 6

Figure 6. La Grange Pool, Illinois River, transect locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program ................ 7
vi

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, a U.S. Geological Survey science center, in cooperation with the five Upper Mississippi

River System (UMRS) States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin. The U.S. Army Corps

of Engineers provides guidance and has overall Program responsibility. The mode of operation and respective

roles of the agencies are outlined in a 1988 Memorandum of Agreement.

The UMRS encompasses the commercially navigable reaches of the Upper Mississippi River, as well as

the Illinois River and navigable portions of the Kaskaskia, Black, St. Croix, and Minnesota Rivers. Congress

has declared the UMRS to be both a nationally significant ecosystem and a nationally significant commercial

navigation system. The mission of the LTRMP is to provide decision makers with information for maintaining

the UMRS as a sustainable large river ecosystem given its multiple-use character. The long-term goals of the

Program are to understand the system, determine resource trends and effects, develop management

alternatives, manage information, and develop useful products.

This report presents the results of aquatic vegetation surveys conducted by field station personnel under

direction of the Environmental Management Technical Center during the 1993 growing season. Selected areas

in Pools 4, 8, 13, and 26 of the Upper Mississippi River and La Grange Pool on the Illinois River were

surveyed. This report satisfies, for 1993, Task 2.2.4.6, Evaluate and Summarize Annual Present-Day Results

under Goal 2, Monitor Resource Change of the Operating Plan (U.S. Fish and Wildlife Service 1993). The

purpose of this report is to provide a summary of data regarding the distribution and abundance of submersed

aquatic vegetation collected from the field stations for 1993. This report was developed with funding provided

by the Long Term Resource Monitoring Program.
1993 Annual Status Report

A Summary of Aquatic Vegetation Monitoring at

Selected Locations in Pools 4, 8, 13, and 26 and

La Grange Pool of the Upper Mississippi River System

by

Sara Rogers, Theresa Blackburn, Kris Kruse, Heidi Langrehr, 

John Nelson, and Andrew Spink

Abstract

Aquatic vegetation of the Upper Mississippi River System is monitored as part of the Long Term Resource

Monitoring Program. This report summarizes the 1993 effort of monitoring submersed aquatic vegetation (SAV)

along permanently established transects in vegetated locations within certain LTRMP study reaches, specifically

Pools 4, 8, 13, and 26 of the Upper Mississippi River and La Grange Pool of the Illinois River. Data are collected

during two sampling windows, mid-May through mid-June, and mid-July through August. Fifteen species of

SAV were found along transects during the 1993 season. The greatest number of species found (12) was in

Pool 4 and the fewest number found (2) was in Pool 26. Coon’s tail and sago pondweed were the only species

found in every study pool during both spring and summer sampling. In all study reaches except La Grange Pool,

the frequency of several species of SAV changed between sampling periods, with decreases especially common

among several species of pondweeds. Several other species also decreased in Pools 13 and 26 between sampling

periods. Conversely, several species increased in frequencies in Pool 8 between periods. The proportion of sites

containing SAV declined during the season in Pools 4, 13, and 26, but not in Pool 8 or La Grange Pool.

Introduction

Aquatic vegetation of the Upper Mississippi River System (UMRS) is monitored as part of the Long Term

Resource Monitoring Program (LTRMP; U.S. Fish and Wildlife Service 1993). The trends in the status of the

vegetation are reported in annual status reports, and the data provides a baseline of information to which future

observations can be compared. In combination with other monitoring conducted for the LTRMP, the overall

mission is to provide decision makers with scientifically sound and useful information for effective river

management. The purpose of this report is to document transect sampling at selected locations in 1993. This

report also provides an initial indication of features of submersed aquatic vegetation (SAV) that can be

compared to future monitoring efforts.

Historically, submersed macrophytes have played an important role in the UMRS ecosystem. These plant

communities provide food for migratory waterfowl (Korschgen et. al. 1988) and improve water quality by

stabilizing sediments, filtering out suspended materials, and taking up nutrients that can otherwise support

nuisance algal growth (Barko et al. 1991). Submersed aquatic macrophytes also provide nursery areas for

young fish, serve as spawning habitat, and support invertebrate populations by providing structure and surface

area (Engel 1990).

We have been unable to understand or anticipate many changes in the distribution of SAV within the

UMRS, partly because few studies have adequately addressed the questions. Biologists have high interest and

concern for this important component, however, especially after the mid- to late-1980s when widespread and

sudden declines in the abundance of wild celery (Vallisneria americana) from Pools 5 to 19 were observed

(E. Nelson and C. Cheap, Winona, Minnesota, unpublished data; C. Korschgen, Northern Prairie Wildlife

Research Center, Jamestown, North Dakota, unpublished data; J. Lyons, U.S. Fish and Wildlife Service,

McGregor, Iowa, personal communication; R. Anderson, Western Illinois University, Macomb, personal
2

communication; W. Thrune, U.S. Fish and Wildlife Service, La Crosse, Wisconsin, personal communication).

Among those especially concerned were biologists familiar with the history of the Illinois River. Submersed

aquatic vegetation in much of the river rapidly disappeared during the 1950s and only remnant populations

now survive (Talkington and Semonin 1991).

Long-term monitoring can have a substantialrole in increasing our understanding of trends in this resource

by addressing the following questions: 

(1) How temporally and spatially dynamic is SAV in the UMRS? 

(2) Are we observing short-term fluctuations in one or more species or is SAV becoming irreparably lost?

(3) Based on patterns observed, what factors most likely contribute to the observed changes?

The 1993 growing season was the third year we conducted field surveys for the LTRMP specifically to

collect data on the distribution and relative abundance of SAV throughout each resource trend analysis pool.

The objectives for monitoring aquatic vegetation in the UMRS are to

(1) document the distribution of SAV within selected locations of the UMRS,

(2) compare current distribution of SAV with past or future distribution, and

(3) identify environmental factors potentially responsible for both long- and short-term changes in the

distribution of SAV.

This report partially fulfills the first and second objectives. Fulfillment of the second objective would be

accomplished over the course of the LTRMP beginning in the second year and gaining more significance with

each subsequent year. Fulfillment of the third objective requires research in addition to monitoring. Measuring

the effect of the environment on abundance and distribution requires focused initiatives to explore plant

response to key factors, singly or in combination with one another.

Study Areas

The LTRMP vegetation study areas include river reaches in the UMRS, four on the Mississippi River and

one on the Illinois River (Figure 1). Study areas are referred to herein by the navigation pool designations

according to the U.S. Army Corps of Engineers lock and dam system. Mississippi River navigation pools

studied are Pool 4 (Mississippi River mile [M] 752 to 797), Pool 8 (M679 to 703), Pool 13 (M523 to 557),

Pool 26 (M202 to 242), and La Grange Pool of the Illinois River (Illinois River mile [I]80 to 158). River miles

for the Mississippi River are measured from the confluence of the Mississippi and Ohio Rivers and for the

Illinois River from the confluence of the Mississippi and Illinois Rivers.

These study areas were chosen, in part, to reflect important differences in geomorphology, floodplain land

use, and water level management strategies that exist with the UMRS. Qualitatively, Pools 4, 8, and 13 are

geomorphically complex with numerous backwaters and richly braided side channels and contain the highest

values of total cover for aquatic vegetation (Peck and Smart 1986). Relatively high percentages of the total

aquatic area in these study reaches are composed of contiguous (to the main channel) backwaters, and

relatively low percentages are composed of main channel (Table 1). Pool 26, in a lower impounded reach, is

characterized by relatively low percentages of open water and aquatic vegetation and a high percentage of

agriculture in the floodplain. La Grange Pool is similar to Pool 26 in floodplain composition, but is similar to

Pools 8 and 13 in composition of the aquatic area. In fact, La Grange Pool has the greatest percentage (52.2%)

of contiguous backwaters among the LTRMP study areas, but aquatic vegetation is not present in most of them.
POOL 8

POOL 13

POOL 4

LA GRANGE POOL

POOL 26

ILLINOIS RIVER

MISSISSIPPI 

RIVER

KASKASKIA RIVER

ST. CROIX RIVER

BLACK RIVER

0 200

Kilometers

Minnesota

Iowa

Missouri

Wisconsin

Illinois

OPEN RIVER

3

Figure 1. Main stem of the Upper Mississippi River System with the study reaches used in the Long Term

Resource Monitoring Program submersed vegetation surveys of 1993 (Pools 4, 8, 13, and 26 and La

Grange Pool). The Open River reach was not selected as a study site because of the lack of habitat for

submersed vegetation.

During 1993, surveys of SAV were conducted in Pools 4, 8, 13, and 26 of the Mississippi River, and in

La Grange Pool of the Illinois River (Figure 1). Permanent transects, most of which were established in 1991,

were monitored at several locations throughout each pool where vegetation has grown for most of the

postimpoundment period.

In Pool 4, we sampled SAV at 10 contiguous backwater locations (Figure 2). The transect locations were

distributed in both the upper and lower portions of the pool, but not in Lake Pepin. Upper pool locations

included Dead Slough Lake, Goose Lake, Mud Lake, and Bay City Flats. Lower pool locations (below Lake

Pepin) included Big Lake, Robinson Lake, Lower Peterson Lake, and Peterson Lake. We also monitored Rice

Lake and Big Lake Bay, part of the Big Lake area. A new set of transects was added in Upper Mud Lake

(Appendix A).
4

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1993

monitoring of submersed aquatic vegetation for the Long Term Resource

Monitoring Program.

Table 1. Key features of the floodplain and aquatic area compositions of the five Mississippi and Illinois River study

reaches monitored for vegetation in 1993 for the Long Term Resource Monitoring Program. a

Floodplain composition (%) composition (%) b

Aquatic area

c

Study reach area (ha) water vegetation Agriculture backwater channel

Floodplain Open Aquatic Contiguous Main

d e

Pool 4 28,358 50.5 10.0 12.1 21.3 10.5

Pool 8 19,068 40.1 14.4 0.9 30.6 14.2

Pool 13 34,528 29.7 8.6 27.9 28.5 24.7

Pool 26 51,688 13.4 1.4 65.4 17.3 54.4

La Grange Pool, Illinois River 89,554 15.7 2.2 59.6 52.2 21.3

Table from Gutreuter et al. (1997). a

Data on floodplain composition are from Laustrup and Lowenberg (1994). b

Aquatic area is that portion of the floodplain that is inundated at normal water elevations. Data on the composition of aquatic areas c

are from the Long Term Resource Monitoring Program aquatic areas spatial database.

Submersed vegetation, when detectable, was merged with the open water class. Main channel includes area in the navigation channel

d

and main channel border areas.

Aquatic vegetation includes rooted floating aquatics and emergents only. e

In Pool 8, we sampled SAV at several established locations including Target Lake, Lawrence Lake, a

backwater area near Goose Island, Shady Maple, the interior of Horseshoe Island, and a small isolated

backwater near Stoddard, Wisconsin (Figure 3). The backwater near Stoddard was first monitored during the

second sampling period of 1992. Two additional locations were also monitored for the first year; Blue Lake,

a large isolated backwater in the northwest portion of the pool, and the Pool 8 Islands Habitat Rehabilitation

and Enhancement Project (HREP) location (Boomerang Island; Appendix A).
5

Figure 3. Pool 8, Upper Mississippi River, transect

locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource

Monitoring Program.

Figure 4. Pool 13, Upper Mississippi River, transect

locations for the 1993 monitoring of submersed

aquatic vegetation for the Long Term Resource

Monitoring Program.

In Pool 13, we sampled SAV at seven

locations that were selected in 1991 and were

distributed primarily in the middle and lower

portions of the pool (Figure 4). Locations

included Brown's Lake, Savanna Bay, Spring

Lake, Pomme de Terre, Potter's Marsh, Lower

Johnson Creek, and an aquatic area along the

Johnson Creek Levee (Appendix A). 
6

Figure 5. Pool 26, Upper Mississippi River, transect locations for the 1993 monitoring of

submersed aquatic vegetation for the Long Term Resource Monitoring Program.

In Pool 26, we sampled SAV at four locations (Figure 5). Transect locations were distributed in Swan Lake,

Stump Lake, Fuller Lake, and in the Calhoun Point area, which consists of several backwater lakes, sloughs,

and wet-weather ponds. Stump Lake, Fuller Lake, and Calhoun Point areas are managed by the Illinois

Department of Natural Resources, which conducts water drainage with control structures and pumping for

waterfowl management (Appendix A).

In La Grange Pool, we sampled SAV at three backwater transect locations and one channel border location

(Figure 6). The three backwaters, monitored for the third year, are among the few locations where submersed

vegetation are still found in this river reach. These backwaters are classified as isolated and are protected from

the main stem of the IllinoisRiver by levees. However, Point Lake occasionally receives overflow water from

the main channel of the Illinois River and did so during 1993 when the river was at flood stage. Banner Marsh

(Bulrush Pond ) and Spring Lake are actively managed for fishing and are completely isolated. The fourth

location, a channel border location by Grape Island, was monitored for the second year (Appendix A).

Methods

Transect Sampling

We positioned transects at regular intervals, from 50 to 200 m apart depending on the size of the area, and

perpendicular to shorelines. In some large backwaters, we positioned transects in groups of three or four and

placed several groups throughout the backwater. For example, Peterson Lake (Pool 4) has three transects in

the upper portion, three transects in the middle portion, and four transects in the lower portion. 
7

Figure 6. La Grange Pool, Illinois River, transect locations for the 1993 monitoring of submersed aquatic

vegetation for the Long Term Resource Monitoring Program.

Transect sampling was performed twice at most locations during the 1993 growing season to observe

seasonal changes in species composition and relative frequencies. Spring sampling was conducted between May

15 and June 15, and summer sampling was conducted between July 15 and August 30. In Pool 8, two new

locations (Blue Lake and Pool 8 Island HREP) were sampled only during the summer sampling period. In La

Grange Pool, Grape Island transect location was sampled only during the spring sampling period.

Sampling along the transects was at regularly spaced intervals(sites) such that a grid-like sampling scheme

of evenly distributed sampling sites was imposed over a backwater or vegetated area. Sites were generally 15 m

apart in Pools 8, 13, and 26 and in La Grange Pool, but 30 m apart in Pool 4 because several of the backwaters

were too large to sample at the 15-m interval (Appendix A). The sampling technique was modified from a

technique used by Jessen and Lound (1962). At each site along a transect, a 2-m diameter sampling area was

visualized and divided into three portions. We sampled plants once within each of the three portions by casting

a long-handled thatching rake to the bottom and twisting it to snag plants—instead of dragging it as did Jessen

and Lound. The thatching rake has a 15-inch head with 20, 5-inch-long teeth and samples about 0.1 m . The 2

submersed species on the rake were identified and recorded. After all three casts were made, each species

recovered was assigned a rating from 1 to 4—instead of from 1 to 5 as did Jessen and Lound—based on the

number of times each species appeared on the rake at each sampling site. A rating of 4 was assigned only if

a species completely covered the rake teeth on all three casts.
8

If floating-leaved species were present, they were recorded and assigned a rating based on four cover

classes (1–25%, 26–50%, 51–75%, and 76–100% visible vegetative cover within the sample area). Floatingleaved species found during sampling are listed in the taxa list (Appendix B).

Fassett (1966) and Gleason and Cronquist (1991) were the primary keys used for plant identification.

Scientific nomenclature and common names were taken from the U.S. Department of Agriculture PLANTS

Database on the Internet (www.itis.usda.gov/). A list of common and scientific names of plants is in Table 2.

Table 2. Submersed and floating-leaved aquatic vegetation most likely to be found in the area covered by the Long Term

Resource Monitoring Program, arranged alphabetically by common name within family.

Family Common name Scientific name a,b a

Ceratophyllaceae Coon's tail, coontail Ceratophyllum demersum

Characeae Chara Chara spp.

Characeae Nitella Nitella spp.

Haloragaceae Shortspike watermilfoil, Myriophyllum sibiricum Komarov

Northern watermilfoilb

Haloragaceae Spike watermilfoil, Myriophyllum spicatum L.

Eurasian watermilfoilb

Hydrocharitaceae Canadian waterweed Elodea canadensis

Hydrocharitaceae Western waterweed Elodea nuttallii Planch.

Hydrocharitaceae Wild celery , American eelgrass Vallisneria americana Michx. b

Lentibulariaceae Common bladderwort Utricularia macrorhiza Le Conte

Najadaceae Brittle waternymph Najas minor All.

Najadaceae Nodding waternymph, Najas flexilis (Willd.) Rostk. & Schmidt

bushy pondweed

Najadaceae Slender waternymph Najas gracillima (A. Braun ex Engelm.)

Magnus

Najadaceae Southern waternymph Najas guadalupensis (Spreng.) Magnus

Nymphaeaceae American lotus Nelumbo lutea (Willd.) Pers.

Nymphaeaceae White waterlily Nymphaea odorata Ait.

Nymphaeaceae Yellow pondlily Nuphar lutea (L.) Sm

Onagraceae Floating primrosewillow Jussiaea repens L.

Pontederiaceae Water stargrass, Heteranthera dubia (Jacq.) MacM.

grassleaf mudplantain

Potamogetonaceae Curly pondweed, Potamogeton crispus L.

curlyleaf pondweed

Potamogetonaceae Flatstem pondweed Potamogeton zosteriformis Fern.

Potamogetonaceae Illinois pondweed Potamogeton illinoisensis Morong.

Potamogetonaceae Longleaf pondweed, Potamogeton nodosus Poir

river pondweedb

Potamogetonaceae Leafy pondweed Potamogeton foliosus Raf.

Potamogetonaceae Ribbonleaf pondweed Potamogeton epihydrus Raf.

Potamogetonaceae Richardson’s pondweed Potamogeton richardsonii (Benn.) Rydb.

Potamogetonaceae Small pondweed Potamogeton pusillus L.

Potamogetonaceae Sago pondweed Potamogeton pectinatus L.

Potamogetonaceae Variableleaf pondweed Potamogeton gramineus L.
Table 2. Continued.

Family Common name Scientific name a,b a

9

Ranunculaceae Longbeak buttercup Ranunculus longirostris Godron.

Ranunculaceae White water-crowfoot Ranunculus trichophyllus Chauix.

Zannichelliaceae Horned pondweed Zannichellia palustris L.

Scientific nomenclature and common names follow the U.S. Department of Agriculture PLANTS Database on the Internet

a

(www.itis.usda.gov/).

Common names most often used by Upper Mississippi River managers are also included if different from the common names listed b

in the U.S. Department of Agriculture PLANTS Database.

If a species was not collected during the 1991 or 1992 seasons or could not be identified in the field, it was

collected for reference and archiving. After drying, pressing, mounting, and labeling, specimens were stored

at each field station. Two species of narrow-leaved pondweeds, small pondweed (Potamogeton pusillus) and

leafy pondweed (P. foliosus), collectively referred to as small and leafy pondweeds, were not distinguished

from each other during field sampling, and were also combined during analysis. Two species of macroalgae,

chara (Chara spp.) and nitella (Nitella spp.), were included in the analysis with the vascular plants.

Environmental Factors

To acquire information on the relationship between macrophyte presence and sediment texture, we recorded

the sediment type most often found for each transect. The sediment types were cataloged subjectively into three

broad categories (silt/clay, mostly silt with sand, mostly sand with silt) based on visual and tactile

characteristics. Water depth was measured at each transect site with a depth pole. 

Statistical Analysis

The frequency of a species is defined as fi = ji/n where ji = number of sample sites containing species I on

at least one of the three rake casts, and n = total number of sample sites. Relative frequency of a species is

defined as rf = e /Ef where e = the number of rake grabs for species I and Ef = number of rake grabs for all

i i i

species. Species of floating-leaved vegetation were not included in the calculations because our primary

concern with this sampling methodology is with changes in submersed vegetation. To test for significant

changes in frequencies for a species between the two sampling periods, a value for Z was calculated using the

following formula:

Z =p - p //pq[(1/n )+(1/n )] 1 2 1 2

where

p =j +j /n +n ;

1 2 1 2

q = 1-p;

p and p are the spring and summer proportions, respectively; 1 2

n and n equal the number of sampling sites, spring and summer, respectively; 1 2

j and j = number of times species j was found during the spring and summer sampling periods, 1 2

respectively; and 

Z-values were calculated for each species and for each location within a pool.
10

Chi-square tests were used to test for significant changes in the proportion of sites with SAV to the total

number of sites sampled between sampling periods. All analysis was done using the Statistical Analysis System

(SAS; SAS Institute, Inc., Cary, North Carolina).

Informal Surveys

To gain perspective on the distribution and composition of SAV in habitats other than transect locations,

we surveyed many portions of each pool where vegetation was likely to be present. Aerial photographs and

bathymetry maps were used to locate sites supporting or likely to support SAV. Pools 4, 8, and 13 were

surveyed by boating along channel border habitats and through other areas most likely to support vegetation

not covered by transect sampling. If vegetated areas or patches of vegetation were seen at or near the surface,

samples were gathered with a rake. An estimate of abundance (rare, common, abundant) was given to each

species. Species composition, approximate bed size, water depth, substrate type, and location of the vegetated

areas and patches were recorded. Informal surveys were not conducted in Pool 26 or in La Grange Pool

because previous surveys revealed that areas with SAV are generally scarce.

Results

All Pools

During 1993, we found 15 species of SAV atsites along transects across study pools (Table 3). One species

included was a non-vascular plant belonging to the muskgrass (Characeae) family. We also found several

species of floating-leaved plants and have included them in our species list (Appendix B). No additional

species were found during informal surveys that were not found at transect locations. The most species found

(12) during any one sampling period was at transect sites in Pool 4, during spring sampling, and the fewest

found (2) was in Pool 26, during summer sampling. Coon’s tail and sago pondweed were the only species

present in every study pool during both spring and summer sampling. Curly pondweed and Eurasian

watermilfoil were also prevalent species, present in all but Pool 26. Curly pondweed, however, declined in

frequency between spring and summer sampling in all pools and sago pondweed declined in all pools except

La Grange Pool, where it was present at a frequency below 5% during both sampling periods. 

Many species, including Canadian waterweed, horned pondweed, flatstem pondweed, small and leafy

pondweeds, longleaf pondweed, nodding waternymph, and water stargrass were distributed in at least two

pools, but usually at frequencies below 10%. We found wild celery in Pools 4 and 13, but at a frequency above

10% only in Pool 4 during summer sampling. Two additional species, western waterweed and chara, were

found only in La Grange Pool and at low frequencies.

Spring sampling was dominated by sago pondweed, curly pondweed, and coon’s tail in Pools 4 and 8, with

a combined relative frequency greater than 80%. In Pools 13 and 26, coon’s tail and sago pondweed

contributed to greater than 70% of the relative frequencies. In La Grange Pool, Eurasian watermilfoil, curly

pondweed, and coon’s tail contributed to a combined relative frequency of more than 80%. 

Eurasian watermilfoil and coon’s tail dominated summer sampling in Pool 8 with a combined relative

frequency greater than 70%. Coon’s tail, flatstem pondweed (or water stargrass), Canadian waterweed, and

Eurasian watermilfoil reached a combined relative frequency of more than 80% in Pool 13. Coon's tail and

sago pondweed were found at very low frequencies only in the summer sampling in Pool 26. Eurasian

watermilfoil had the highest relative frequency, and along with coon’s tail, reached a combined relative

frequency greater than 80% in La Grange Pool.
11

Table 3. Frequencies and relative frequencies (%) of species in Pools 4, 8, 13, and 26 of the Upper Mississippi

River and La Grange Pool (LG) of the Illinois River in 1993.a

Spring Summer

4 8 13 26 LG 4 8 13 26 LG

Species Fre Fre Fre Freq Fre Freq Fre Fre Fre Freq Freq Fre Fre Fre Fre Fre Fre Fre Fre Fre

q q q q q q q q q q q q q q q q

Rel Rel. Rel. Rel Rel Rel Rel Rel Rel Rel

Canadian waterweed 5.0 6.8 1.7 1.3 6.2 5.5 1.7 1.1 – – 7.9 15.3 3.5 3.5 10.1 17.5 – – – –

b

Chara – – – – – – – – 7.6 5.6 – – – – – – – – 7.0 7.0

Common bladderwort 0.1 0.1 – – – – – – – – – – 3.8 4.6 – – – – – –

Coon's tail 9.1 13.7 20.0 17.1 21.5 22.2 43.9 50.1 20.4 13.4 9.3 19.2 32.2 49.6 18.3 33.3 0.9 50.0 22.7 20.4

Curly pondweed 15.5 24.7 26.7 38.3 4.9 3.7 – – 27.0 16.8 0.9 1.1 5.9 5.3 0.3 0.4 – – 1.6 1.0

Eurasian watermilfoil 2.2 3.6 15.4 17.2 8.4 7.6 – – 65.8 53.2 2.5 4.9 22.0 24.4 8.3 14.2 – – 63.0 61.2

Flatstem pondweed 0.5 0.5 0.3 0.3 – 3.4 – – – – 1.0 1.4 1.0 0.8 11.2 19.7 – – – –

c

Horned pondweed 0.1 0.1 0.5 0.4 – – – – 4.7 2.3 – – – – – – – – – –

Longleaf pondweed 0.3 0.4 – – 3.9 4.7 7.4 8.2 2.4 1.0 0.4 0.7 0.7 1.0 1.8 2.1 – – 2.2 1.8

Nodding waternymph – – 0.3 0.3 0.3 0.2 – – – – 0.1 0.3 0.8 0.9 0.5 0.6 – – 2.2 1.4

Sago pondweed 23.6 42.6 24.0 25.0 46.0 52.3 53.8 40.6 2.4 0.9 7.2 15.0 9.0 9.5 3.4 3.9 1.1 50.0 3.2 1.8

Small and leafy 3.7 5.0 – – – – – – 0.5 2.0 1.5 2.7 0.1 0.2 – – – – 0.5 0.2

pondweeds

Water stargrass 1.8 1.9 – – 3.8 3.4 – – – – 2.6 5.2 0.3 0.2 ? ? – – – –

d

Western waterweed – – – – – – – – 9.0 4.7 – – – – – – – – 7.0 5.3 c

Wild celery 0.4 0.4 – – 0.3 0.2 – – – – 14.0 34.0 – – 5.4 8.2 – – – –

Data are based on all transect locations combined within a pool. Rounding may cause relative frequency columns to not total a

100%.

The symbol “–” indicates the species was not found. b

Flatstem pondweed relative frequency may also include water stargrass in Pool 13 c .

Verification of specimen needed for positive identification. d

The proportion of sites vegetated with SAV decreased significantly in all pools, but most remarkably in

Pools 13 and 26 where summer flooding was more severe (Table 4). The highest proportion of vegetated sites

was in La Grange Pool where transects are located in backwaters that are usually protected from high

turbidity levels and flows of the Illinois River main channel.

Table 4. Proportion of sites with submersed aquatic vegetation to total number of

sites sampled at transect locations during the 1993 spring and summer

sampling periods. 

Location Spring Summer 

Pool 4 43.2 29.5 (p < 0.01)a

Pool 8 57.2 48.3 (p < 0.01)

Pool 13 60.8 22.6 (p < 0.01)

Pool 26 79.7 2.1 (p < 0.01)

La Grange Pool 94.2 82.7 (p < 0.01)

Probability values for differences between sampling periods is given in parentheses.

a

P-values are based on Chi-square tests with a 0.05 level of significance.
12

Water Depths and Substrates

Mean water depths where submersed aquatic plants grew along transects revealed that depths were from

1.1 m in Pool 8 to 2.3 m in Pool 26 during spring sampling and from 1.1 m in Pool 8 to 3.5 m in Pool 26

during summer sampling (Table 5). Water depths were unusually deep in all the pools, especially in Pool 26,

because of prolonged summer flooding.

Table 5. Mean depths of submersed aquatic vegetation along sampling transects in Pools 4, 8, 13, and 26 of the Upper

Mississippi River and La Grange Pool of the Illinois River during the 1993 spring and summer sampling periods.

Location spring sampling deviation N summer sampling deviation N

Mean depth Standard Mean depth Standard

Pool 4 1.5 0.6 395 1.5 0.4 271

Pool 8 1.1 0.4 439 1.1 0.3 516

Pool 13 1.4 0.6 549 1.1 0.4 200

Pool 26 2.3 0.9 458 3.5 0.2 11

La Grange Pool 1.5 0.4 127 1.6 0.5 58

The majority of SAV sites were found on silt substrates throughout all pools. Pools 4 and 13 also reported

sand substrate at sites with SAV (Table 6).

Table 6. Relative presence of (%) substrate types along transects containing submersed aquatic vegetation during the

1993 spring and summer sampling periods.

Relative presence

Substrate type (n = 104) (n = 76) (n = 124) (n = 71) (n = 30)

Pool 4 Pool 8 Pool 13 Pool 26 Pool

La Grange

Silt/clay mix 76.9 92.1 66.1 100.0 60.0

Mostly silt with sand 4.8 7.9 15.3 – 26.7 a

Mostly sand with silt 18.3 – 18.6 – 13.3

The symbol “–” indicates the substrate type was not found. a

Pool 4

We found 12 species of SAV along Pool 4 transects during the spring sampling period and 11 during the

summer sampling period (Table 7). No additional species were found during informal surveys. More species

were found along transects in lower Pool 4 (below Lake Pepin) than in the upper pool (above Lake Pepin;

Appendix B). Species with the highest frequencies during spring sampling were sago pondweed (23.6%), curly

pondweed (15.5%), and coon’s tail (9.1%). These three contributed to more than 80% of the relative

frequencies during the spring sampling period. Both sago pondweed and curly pondweed declined in frequency

between spring and summer sampling periods, whereas the frequency of coon’s tail remained similar between

sampling periods (Table 7). 
13

Table 7. Frequencies and relative frequencies (%) of species in Pool 4 during the 1993 spring and summer sampling

periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 5.0 7.9 6.8 15.3

Common bladderwort 0.1 – 0.1 –

b

Coon's tail 9.1 9.3 13.7 19.2

Curly pondweed 15.5 0.9 24.7 1.1

Eurasian watermilfoil 2.2 2.5 3.6 4.9

Flatstem pondweed 0.5 1.0 0.5 1.4

Horned pondweed 0.1 – 0.1 –

Longleaf pondweed 0.3 0.4 0.4 0.7

Nodding waternymph – 0.1 – 0.3

Sago pondweed 23.6 7.2 42.6 15.0

Small and leafy pondweeds 3.7 1.5 5.0 2.7

Water stargrass 1.8 2.6 1.9 5.2

Wild celery 0.4 14.0 0.4 34.0

Frequencies and relative frequencies are based collectively on all transect locations where sampling was performed twice during a

the growing season. Rounding may cause relative frequency columns to not total 100%.

The symbol “–” indicates the species was not found. b

During the summer sampling, wild celery was the only species with a frequency greater than 10% and

Canadian waterweed, coon’s tail, and sago pondweed were the only species with frequencies above 5%. These

species had a combined relative frequency greater than 80%. Species encountered rarely (< 2.0%) included

water stargrass, wild celery, common bladderwort, and horned pondweed during spring sampling, nodding

waternymph during summer sampling, and flatstem and longleaf pondweeds during both sampling periods

(Table 7).

Two species with the highest spring frequencies, sago pondweed and curly pondweed, declined significantly

(based on z-tests) at several transect locations during the weeks between the spring and summer sampling

periods. Sago pondweed declined at upper Pool 4 transect locations including Bay City Flats, Dead Slough

Lake, and Mud Lake. Curly pondweed declined at Peterson Lake, Lower Peterson Lake, Big Lake, Robinson

Lake, and Big Lake Bay. Small and leafy pondweeds also declined in Robinson Lake. These declines were

responsible for the change in the proportion of sites vegetated with SAV between sampling periods (Table 4).

Wild celery increased at four lower pool locations: Robinson Lake, Big Lake, Peterson Lake, and lower

Peterson Lake; and Canadian waterweed increased in Robinson Lake. No other species revealed significant

change between the two sampling periods (Table 8). 
14

Table 8. Locations in Pool 4 where species were present during the 1993 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a b a

Canadian waterweed Big Lake Bay Big Lake Robinson Lake

Lake Peterson Lake

Lower Peterson

Common bladderwort Big Lake

Coon's tail Big Lake

Big Lake Bay

Lower Peterson Lake 

Peterson Lake

Rice Lake

Robinson Lake

Upper Mud Lake

Curly pondweed Big Lake Peterson Lake

Big Lake Bay Rice Lake

Lower Peterson Lake

Peterson Lake

Robinson Lake

Eurasian watermilfoil Big Lake

Big Lake Bay

Peterson Lake 

Rice Lake 

Robinson Lake 

Flatstem pondweed Big Lake

Big Lake Bay 

Peterson Lake 

Robinson Lake

Horned pondweed Peterson Lake 

Longleaf pondweed Big Lake

Big Lake Bay 

Rice Lake

Nodding waternymph Big Lake 

Sago pondweed Bay City Flats Big Lake 

Dead Slough Lake Big Lake Bay 

Mud Lake Goose Lake

Lower Peterson Lake

Peterson Lake 

Rice Lake 

Robinson Lake

Upper Mud Lake
Table 8. Continued.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a b a

15

Small and leafy pondweeds Robinson Lake Big Lake 

Big Lake Bay

Peterson Lake 

Rice Lake 

Upper Mud Lake

Water stargrass Big Lake 

Lower Peterson Lake

Peterson Lake

Robinson Lake

Wild celery Big Lake

Peterson Lake 

Robinson Lake 

Species that increased or decreased in frequency at a location are significant at the 0.05 probability level (based on z-tests). a

Species that did not change significantly may have been untestable due to small sample size during one or both sampling periods. b

Pool 8

We found eight species at Pool 8 transect locations during the spring sampling period and 11 species at the

same transect locations during the summer sampling period. Horned pondweed was found in the spring, but

not during the summer. Common bladderwort, longleaf pondweed, small and leafy pondweeds, and water

stargrass were found during summer, but not during spring sampling. Thus, a total of 12 species were found

during both seasons (Appendix B). Coon's tail, curly pondweed, and sago pondweed reached frequencies of

at least 20% during the spring sampling period, but the frequency of sago and curly pondweed decreased to

less than 10% by the summer sampling period. Eurasian watermilfoil and coon’s tail both increased in

frequency. Species rarely found (frequency less than 2%), including Canadian waterweed, common

bladderwort, flatstem pondweed, nodding waternymph, small and leafy pondweeds, and water stargrass,

increased slightly as well.

During the spring sampling period, curly pondweed, coon’s tail, and sago pondweed contributed to greater

than 80% of the relative frequencies. During the summer sampling period, coon’s tail contributed to nearly

50% of the relative frequencies and when combined with Eurasian watermilfoil and sago pondweed,

contributed to more than 80% of the relative frequencies (Table 9).

Significant decreases were noted for sago pondweed in most locations where the species was found including

Lawrence Lake, Target Lake, Horseshoe Island, and Goose Island. Curly pondweed declined in overall

frequency between the two sampling periods in Lawrence Lake. Significant increases in at least one species

occurred in Lawrence Lake, Goose Island, and Stoddard locations (Table 10). Although species both decreased

and increased at individual locations, the proportion of sites vegetated with submersed species decreased

significantly between spring and summer sampling periods, affected primarily by the decline in the two species

with the highest spring frequencies, sago pondweed and curly pondweed (Table 4).
16

Table 9. Frequencies and relative frequencies (%) of species in Pool 8 during the 1993 spring and summer sampling

periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 1.7 3.5 1.3 3.5

Common bladderwort – 3.8 – 4.6 b

Coon's tail 20.0 32.2 17.1 49.6

Curly pondweed 26.7 5.9 38.3 5.3

Eurasian watermilfoil 15.4 22.0 17.2 24.4

Flatstem pondweed 0.3 1.0 0.3 0.8

Horned pondweed 0.5 – 0.4 –

Longleaf pondweed – 0.70 – 1.0

Nodding waternymph 0.3 0.8 0.3 0.9

Sago pondweed 24.0 9.0 25.0 9.5

Small and leafy pondweeds – 0.10 – 0.2

Water stargrass – 0.30 – 0.2

Frequencies and relative frequencies are based on all locations pooled together that were sampled twice during the season. Rounding a

may cause relative frequency columns to not total 100%.

The symbol “–” indicates the species was not found. b

Table 10. Locations in Pool 8 where species were present during the 1993 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between 

spring and summer spring and summer spring and summer 

a b a

Canadian waterweed Goose Island Lawrence Lake

Horseshoe Island

Stoddard

Target Lake 

Common bladderwort Lawrence Lake

Target Lake 

Coon's tail Shady Maple Goose Island

Stoddard Lawrence Lake

Target Lake

Curly pondweed Lawrence Lake Goose Island Stoddard

Horseshoe Island

Shady Maple 

Target Lake
Table 10. Continued.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between 

spring and summer spring and summer spring and summer 

a b a

17

Eurasian watermilfoil Goose Island Lawrence Lake

Horseshoe Island

Shady Maple

Target Lake

Flatstem pondweed Goose Island

Lawrence Lake

Target Lake

Horned pondweed Horseshoe Island

Longleaf pondweed Goose Island

Lawrence Lake

Nodding waternymph Horseshoe Island Lawrence Lake

Sago pondweed Goose Island Shady Maple Stoddard

Horseshoe Island

Lawrence Lake

Target Lake

Small and leafy pondweeds Lawrence Lake Stoddard

Water stargrass Lawrence Lake

Species that increased or decreased in frequency at a location are significant at the 0.05 probability level (based on z-tests). a

Species that did not change significantly may have been untestable due to small sample size during one or both sampling periods. b

Pool 13 

We found nine species of SAV along Pool 13 transects during the 1993 sampling season (Appendix B).

All nine species were found during both sampling periods. No additional species were found during informal

surveys. Flatstem pondweed and water stargrass were probably both present, but a distinction between the two

was not made while in the field. Sago pondweed and coon’s tail had the highest frequencies during spring

sampling, at 46% and 21.5%, respectively. Frequencies of all other species in spring were below 10%. By the

summer sampling period, sago pondweed had dropped in frequency to 3.4% and most other species remained

below 10%. Coon’s tail, Eurasian watermilfoil, and nodding waternymph retained similar frequencies between

spring and summer sampling, while increases occurred among Canadian waterweed, flatstem pondweed (or

water stargrass), and wild celery.

During spring sampling, sago pondweed, coon’s tail, and Eurasian watermilfoil, contributed to greater than

80% of the relative frequencies. During summer sampling, flatstem pondweed (or water stargrass), coon’s tail,

Eurasian watermilfoil, and Canadian waterweed shared more than 80% of the relative frequencies (Table 11).

Many species showed significant decreases in frequencies at some locations where they were present

during the 1993 growing season. Thus, the proportion of sites with SAV decreased significantly between spring

and summer sampling periods (Table 4). However, the Johnson Creek area (Johnson Creek and Johnson

Creek levee locations) was the primary location where species significantly increased (Table 12).
18

Table 11. Frequencies and relative frequencies (%) of species in Pool 13 during the 1993 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 6.2 10.1 5.5 17.5

Coon's tail 21.5 18.3 22.0 33.3

Curly pondweed 4.9 0.3 3.7 0.4

Eurasian watermilfoil 8.4 8.3 7.6 14.2

Longleaf pondweed 3.9 1.8 4.7 2.1

Nodding waternymph 0.3 0.5 0.2 0.6

Sago pondweed 46.0 3.4 52.3 3.9

Wild celery 0.3 5.4 0.2 8.2

Other species 3.8 11.2 3.4 19.7 b

Frequencies and relative frequencies are based on all locations pooled together that were monitored during both the spring and

a

summer sampling efforts. Rounding may cause the relative frequencies column to not total 100%.

Other species include either or both water stargrass and flatstem pondweed. b

Table 12. Locations in Pool 13 where species were present during the 1993 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer 

a b a

Canadian waterweed Pomme de Terre Potter’s Marsh Johnson Creek

Johnson Creek Levee

Coon's tail Pomme de Terre Brown's Lake Johnson Creek

Savanna Bay Potter's Marsh Johnson Creek Levee

Spring Lake Savanna Bay

Curly pondweed Johnson Creek Brown’s Lake

Johnson Creek levee Pomme de Terre

Savanna Bay Savanna Bay

Spring Lake

Eurasian watermilfoil Pomme de Terre Potter's Marsh Johnson Creek

Spring Lake Johnson Creek Levee

Flatstem pondweed/ Pomme de Terre Johnson Creek 

water stargrass Potter's Marsh Johnson Creek Levee

Savanna Bay

Spring Lake

Longleaf pondweed Spring Lake Brown's Lake

Johnson Creek

Johnson Creek Levee

Pomme de Terre

Savanna Bay
Table 12. Continued.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer 

a b a

19

Nodding waternymph Johnson Creek

Johnson Creek Levee

Sago pondweed Brown's Lake

Johnson Creek 

Johnson Creek Levee

Pomme de Terre 

Potter's Marsh

Savanna Bay

Spring Lake

Wild celery Brown's Lake Johnson Creek

Potter's Marsh Johnson Creek Levee

Pomme de Terre

Species that increased or decreased in frequency at a location are significant at the 0.05 probability level (based on z-tests). a

Species that did not change significantly may have been untestable due to small sample size during one or both sampling periods. b

Informal surveys conducted in July were a reduced effort for Pool 13 because of high water levels

associated with the 1993 flood. Between the difficulty of sampling or finding SAV in high water, less than

25 sites with SAV were located. No additional species were found during informal surveys.

Pool 26

We found only four species of SAV during the spring sampling period and only two during the summer

sampling period in 1993. Frequencies and relative frequencies were dominated by coon's tail and sago

pondweed, with coon’s tail owning the highest relative frequency during the spring sampling period. By the

summer sampling period, which was still during high water levels associated with the 1993 flood, no species

reached a frequency of 2%, making SAV nearly nonexistent at the transect locations (Table 13). The

proportion of sites vegetated with SAV was consequently affected between spring and summer sampling by

the decreases in frequencies and in species that were originally present during the spring effort (Table 14).

Table 13. Frequencies and relative frequencies (%) of species in Pool 26 during the 1993 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 1.7 – 1.1 –

b

Coon's tail 43.9 0.9 50.1 50.0

Longleaf pondweed 7.4 – 8.2 –

Sago pondweed 53.7 1.1 40.6 50.0

Frequencies and relative frequencies are based on all locations pooled together that were sampled twice during the season. Rounding

a

may cause the relative frequencies column to not total 100%. Locations that were sampled twice during the season were Calhoun

Point, Stump Lake, Swan Lake, and Fuller Lake.

The symbol “–” indicates the species was not found. b
20

Table 14. Locations in Pool 26 where species were present during the 1993 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between 

spring and summer spring and summer spring and summer

a b a

Canadian waterweed Stump Lake Calhoun Point 

Coon's tail Calhoun Point 

Fuller Lake

Stump Lake

Longleaf pondweed Stump Lake

Sago pondweed Calhoun Point

Stump Lake

Swan Lake

Species that increased or decreased in frequency at a location are significant at the 0.05 probability level (based on z-tests). a

Species that did not change significantly may have been untestable due to small sample size during one or both sampling periods. b

Allspecies present significantly declined (based on z-tests) between sampling periods at nearly all locations

where they occurred. Coon’s tail and sago pondweed declined in Fuller and Stump Lakes and at Calhoun

Point. Canadian waterweed and longleaf pondweed both declined at Stump Lake (Table 14).

La Grange Pool

We found 10 species of SAV at transect locations in La Grange Pool in 1993. Nine species were found

during each sampling period; horned pondweed was found in spring but not in summer, and nodding

waternymph was found in summer but not in spring. No species were found at the Grape Island location, which

was sampled only during the spring sampling period.

Species frequencies in La Grange Pool were dominated by Eurasian watermilfoil, followed by curly

pondweed and coon's tail during the spring sampling period (Table 15). These three species contributed to more

than 80% of the relative frequencies during the spring sampling. During the summer sampling period,

coon’s tail and Eurasian watermilfoil made up more than 80% of the relative frequencies whereas curly

pondweed dropped to only 1% relative frequency. All other species were present at frequencies of 10% or less

during both sample periods. La Grange Pool backwaters are the only locations within our study areas where

we found western waterweed.

Table 15. Frequencies and relative frequencies (%) of species in La Grange Pool, Illinois River, during the 1993 spring

and summer sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Chara 8.4 7.0 5.6 7.0

Coon's tail 22.6 22.7 13.4 20.4

Curly pondweed 30.0 1.6 16.7 1.0

Eurasian watermilfoil 73.1 63.0 53.0 61.2

Horned pondweed 5.2 – 2.3 –

b
Table 15. Continued.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

21

Longleaf pondweed 2.6 2.2 1.0 1.8

Nodding waternymph – 2.2 – 1.4

Sago pondweed 1.6 3.2 1.1 1.8

Small and leafy pondweeds 1.6 0.5 2.0 0.2

Western waterweed 10.0 7.0 4.7 5.3

Frequencies and relative frequencies are based on all locations pooled together that were sampled twice during the season. Rounding

a

may cause the relative frequencies column to not total 100%.

The symbol “–” indicates the species was not found. b

Based on z-tests, there was little significant change in species frequencies between sampling periods. The

one exception was Eurasian watermilfoil, which declined at the Spring Lake location (Table 16). During the

growing season, there was a significant decline in the proportion of sites with SAV. The change was affected

primarily by the decline of curly pondweed and Eurasian watermilfoil in Spring Lake.

Table 16. Locations in La Grange Pool, Illinois River, where species were present during the 1993 spring and summer

sampling periods.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a b a

Chara Spring Lake

Coon's tail Bulrush Pond

Point Lake

Spring Lake

Curly pondweed Spring Lake Bulrush Pond

Eurasian watermilfoil Spring Lake Bulrush Pond

Horned pondweed Bulrush Pond

Spring Lake

Longleaf pondweed Bulrush Pond

Nodding waternymph Bulrush Pond

Spring Lake

Sago pondweed Bulrush Pond

Spring Lake

Small and leafy pondweeds Bulrush Pond

Western waterweed Point Lake

Spring Lake

Species that increased or decreased in frequency at a location are significant at the 0.05 probability level (based on z-tests). a

Species that did not change significantly may have been untestable due to small sample size during one or both sampling periods. b
22

Acknowledgments

The authors acknowledge J. Winkelman and T. Cook for their helpful comments to the manuscript. We also

thank the team leaders and summer staff at the participating agencies for their support and assistance in the

field: Illinois Natural History Survey, Alton; Illinois Natural History Survey, Havana; Iowa Department of

Natural Resources, Bellevue; Minnesota Department of Natural Resources, Lake City; and Wisconsin

Department of Natural Resources, Onalaska.

References

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Publication 128. Illinois State Water Survey, Champaign. 51 pp.

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A-1

Appendix A

Locations, Number of Transects and Sites, Sampling Dates, and Distances Between

Sites Sampled in Pools 4, 8, 13, and 26 of the Upper Mississippi River and La Grange

Pool of the Illinois River during the 1991 through 1994 sampling seasons.

Location transects spring summer spring summer sites (m)

Number of of sites in of sites in sampled in sampled in between

Number Number Dates Dates Distance

Pool 4

Bay City Flats 3 78 70 6/10–11 8/11, 13 30

(M787.0; 

Catherine Pass)a

Big Lake 3 29 26 5/26 7/28 30

(M758.0)

Big Lake 5 152 159 6/1, 3 7/29; 8/2, 29 30

(M757.5)

Big Lake Bay 3 35 30 5/26 7/26 30

(M758.5)

Dead Slough Lake 9 133 115 6/8, 10 8/4, 9 30

(M789.2, M788.5,

M788.0)b

Goose Lake 3 28 24 6/4 8/9 30

(M788.G)c

Lower Peterson Lake 4 118 132 5/19–20 7/15–16 30

(M753.5)

Mud Lake 3 57 51 6/4 8/4 30

(M791.3)

Peterson Lake 6 56 58 5/17 7/15 30

(M754.8, M754.5)

Robinson Lake 9 187 211 5/20–21, 25 7/20–22 30

(M758.R)

Upper Mud Lake 4 42 42 30

(M791.5)

 Total Pool 4 48 915 918 15 15

Pool 8

Blue Lake 3 (summer) not sampled 122 not sampled 8/19–20 15

(M697.0)

Goose Island 5 114 114 5/26 7/23, 29 15

(M692.0)

Horseshoe HREP 5 75 82 6/10 8/11 15 d

(M687.0)
Location transects spring summer spring summer sites (m)

Number of of sites in of sites in sampled in sampled in between

Number Number Dates Dates Distance

A-2

Lawrence Lake 6 (spring) 247 435 5/20–21, 25; 6/1 7/30; 8/3, 5–6, 15

(M691.0) 10 (summer) 10, 24–25

Pool 8 Islands 3 (summer) not sampled 75 not sampled 8/26 15

(M686.0)

Shady Maple 3 114 101 6/3 7/22 15

(M690.0)

Stoddard 4 48 46 5/27–28 7/20 15

(M684.0)

Target Lake 9 (spring) 169 298 6/8, 11 8/4, 13, 16 15

(M696.0) 11 (summer)

Total Pool 8 32 (spring) 767 1,273 11 18

44 (summer)

Pool 13

Brown's Lake 25 325 308 6/3–4, 8–11 7/30; 8/17–19 15

(M545.1, M544.5)

Johnson Creek Levee 4 88 82 6/14–15 8/11 15

(M523.5)

Lower Johnson Creek 2 53 59 5/20 7/26 15

(M523.0)

Pomme de Terre 5 78 77 5/19 8/6 15

(M526.0)

Potter's Marsh 6 74 75 6/11 8/10 15

 (M524.0)

Savanna Bay 12 135 150 5/21, 25–26 7/29–30; 8/3 15

(M541.5, M540.5, 

M539.5)

Spring Lake 12 149 130 5/26, 28; 6/1 8/3, 5 15

(M534.8, M533.6, 

M532.0)

Total Pool 13 66 902 881 16 12

Pool 26

Calhoun Point 17 157 156 5/25, 27 8/23–24 15

(I003.0)e,f

Fuller Lake 2 29 32

(I011.5)

Swan Lake 11 291 146 5/19–20, 24 8/26–27 15

(I005.5)
Location transects spring summer spring summer sites (m)

Number of of sites in of sites in sampled in sampled in between

Number Number Dates Dates Distance

A-3

Stump Lake 8 174 194 6/1, 3 8/25–26 15

(I010.0)

Total Pool 26 38 (spring) 651 528 7 6

32 (summer)

La Grange Pool

Banner Marsh 2 18 16 6/10 8/11–12 15

(I140.7; 

Bulrush Pond)d

Grape Island 3 (spring) 21 not sampled not sampled 15

(I086.4)

Point Lake 6 28 26 6/14–15 8/10 15

(I100.0)

Spring Lake 5 144 143 5/23, 25, 27–28; 7/19, 21–22; 15

(I135.5) 6/2–3 8/5, 18

Total La Grange Pool 16 (spring) 211 185 9 8

13 (summer)

Locally recognized name. a

Mississippi River miles, measured from the confluence of the Mississippi and Ohio Rivers. b

“G” and “R” to distinguish this lake from another lake with the same river mile. c

Habitat Rehabilitation and Enhancement Project. d

Illinois River miles, measured from the confluence of the Mississippi and Illinois Rivers. e

Pool 26 is located at the confluence of the Illinois and Mississippi Rivers and the portions named here extend up the Illinois River, f

are managed by the Illinois Department of Natural Resources, and are disignated by Illinois River miles.
B-1

Appendix B

Species of Submersed and Floating-leaved Aquatic Macrophytes Occurring at

Transect Sites in Pools 4, 8, 13, and 26 of the Upper Mississippi River and

La Grange Pool of the Illinois River

Species Pool 4 Pool 8 Pool 13 Pool 26 Pool a

La Grange

Submersed Aquatic Species

Canadian waterweed x x x x –

(Elodea canadensis L.)

b c

Chara – – – – x

(Chara spp.)

Common bladderwort x x – – –

(Utricularia macrorhiza L.) 

Coon's tail x x x x x

(Ceratophyllum demersum L.)

Curly pondweed x x x – x

(Potamogeton crispus L.)

Eurasian watermilfoil

(Myriophyllum spicatum L.) x x x – x

Flatstem pondweed

(Potamogeton zosteriformis) x x – –

x

Horned pondweed

(Zannichellia palustris L.) x – – x

x

Longleaf pondweed

(Potamogeton nodosus Poiret.) x x x x x

Nodding waternymph

(Najas flexilis [Willd.] Rostke & x x x – x

Schmidt)

Sago pondweed

(Potamogeton pectinatus [Benn] x x x x x

Rydb.)

Small and leafy pondweeds

(Potamogeton pusillus; x x – – x

P. foliosus L.)

Water stargrass

(Heteranthera dubia L.) x x ? – –

d

Western waterweed – – – – x

(Elodea nuttallii [Planch.]

St. John)
Species Pool 4 Pool 8 Pool 13 Pool 26 Pool a

La Grange

B-2

Wild celery, American eelgrass

(Vallisneria americana Michx.) – x – –

x

Floating-leaved Species

American lotus x x x x x

(Nelumbo lutea [Willd.] Pers.)

American white waterlily x x – – –

(Nymphaea odorata Ait.)

Yellow pondlily x x – – –

(Nuphar lutea [L.] Sm.)

Additional species found during 0 0 0 0 0

informal surveys not found

during transect surveys

 Total per pool

 Submersed aquatic 13 12 9 4 10

species 3 3 1 1 1

 Floating-leaved species

Found in lower Pool 4 (below Lake Pepin) only when so indicated. a

The symbol “x” indicates the species was present. b

The symbol “–” indicates the species was not found. c

Water stargrass was probably present in Pool 13, but was not distinguished from flatstem pondweed. d
REPORT DOCUMENTATION PAGE Form Approved

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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

July 1998

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

1993 annual status report: A summary of aquatic vegetation monitoring at selected locations in Pools 4, 8, 13, and 26 and

La Grange Pool of the Upper Mississippi River System

6. AUTHOR(S)

Sara Rogers , Theresa Blackburn , Kris Kruse , Heidi Langrehr , John Nelson , and Andrew Spink 1 2 3 4 5 5

7. PERFORMING ORGANIZATION NAME AND ADDRESS 8. PERFORMING ORGANIZATION

U.S. Geological Survey, Environmental Management Technical Center, 575 Lester Avenue, Onalaska, Wisconsin 54650. 1

Iowa Department of Natural Resources, Mississippi River Monitoring Station, 206 Rose Street, Bellevue, Iowa 52031. 2

Minnesota Department of Natural Resources, 1801 South Oak Street, Lake City, Minnesota 55041. 3

Wisconsin Department of Natural Resources, Onalaska Field Station, 575 Lester Avenue, Onalaska, Wisconsin 54650. 4

Illinois Natural History Survey, Havana Field Station, 704 N. Schrader Avenue, Havana, Illinois 62644. 5

 REPORT NUMBER

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORING

U.S. Geological Survey 

Environmental Management Technical Center 98-P007

575 Lester Avenue

Onalaska, Wisconsin 54650

 AGENCY REPORT NUMBER

11. SUPPLEMENTARY NOTES

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

Release unlimited. Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161 

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Help Desk, 8725 Kingman Road, Suite 0944, Fort Belvoir, VA 22060-6218 (1-800-225-3842 or 703-767-9050).

13. ABSTRACT (Maximum 200 words)

Aquatic vegetation of the Upper Mississippi River System is monitored as part of the Long Term Resource Monitoring Program. This report summarizes the 1993 effort of

monitoring submersed aquatic vegetation (SAV) along permanently established transects in vegetated locations within certain LTRMP study reaches, specifically

Pools 4, 8, 13, and 26 of the Upper Mississippi River and La Grange Pool of the Illinois River. Data are collected during two sampling windows, mid-May through midJune, and mid-July through August. Fifteen species of SAV were found along transects during the 1993 season. The greatest number of species found (12) was in Pool 4

and the fewest number found (2) was in Pool 26. Coon’s tail and sago pondweed were the only species found in every study pool during both spring and summer

sampling. In all study reaches except La Grange Pool, the frequency of several species of SAV changed between sampling periods, with decreases especially common

among several species of pondweeds. Several other species also decreased in Pools 13 and 26 between sampling periods. Conversely, several species increased in

frequencies in Pool 8 between periods. The proportion of sites containing SAV declined during the season in Pools 4, 13, and 26, but not in Pool 8 or La Grange Pool.

14. SUBJECT TERMS 15. NUMBER OF PAGES

Aquatic plant monitoring, submersed aquatic vegetation, Upper Mississippi River System 22 pp. + Appendixes A–B

16. PRICE CODE

17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

 OF REPORT OF THIS PAGE OF ABSTRACT

Unclassified Unclassified Unclassified
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 for maintaining the Upper Mississippi 

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

The LTRMP is a cooperative effort by the U.S. Geological Survey, the U.S. Army Corps

of Engineers, and the States of Illinois, Iowa, Minnesota, Missouri, and Wisconsin.