Long Term Resource Monitoring Program

Program Report

98-P006

1992 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

June 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 
1992 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

Heidi Langrehr

Wisconsin Department of Natural Resources

Onalaska Field Station

575 Lester Avenue

Onalaska, Wisconsin 54650

John Nelson and Susan Romano-Peitzmeyer

Illinois Natural History Survey

Havana Field Station

704 N. Schrader Avenue

Havana, Illinois 62644

June 1998
Suggested citation:

Rogers, S., T. Blackburn, H. Langrehr, J. Nelson, and S. Romano-Pietzmeyer. 1998. 1992 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, June 1998.

LTRMP 98-P006. 24 pp. + Appendixes A–C

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 ........................................................................ vii

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

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

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

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

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

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

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

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

Results and Discussion ............................................................ 10

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

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

Pool 4 ...................................................................... 13

Pool 8 ...................................................................... 16

Pool 13 .................................................................... 18

Pool 26 ..................................................................... 20

La Grange Pool ............................................................... 21

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

References ..................................................................... 23

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

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

Appendix C ................................................................... C-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 1992 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
iv

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 1992 ............ 11

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

at transect locations during the 1992 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

1992 spring and summer transect sampling periods ............................. 13

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

vegetation during the 1992 spring and summer sampling periods .................. 13

Table 7. Frequencies and relative (%) frequencies of species in Pool 4 during the 1992 spring and

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

Table 8. Locations in Pool 4 where species were present during the 1992 spring and summer

sampling periods ....................................................... 15

Table 9. Frequencies and relative (%) frequencies of species in Pool 8 during the 1992 spring and

summer sampling periods ................................................ 17

Table 10. Locations in Pool 8 where species were present during the 1992 spring and summer

sampling periods ....................................................... 17

Table 11. Frequencies and relative frequencies (%) of species in Pool 13 during the 1992 spring and

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

Table 12. Locations in Pool 13 where species were present during the 1992 spring and summer

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

Table 13. Frequencies and relative frequencies (%) of species in Pool 26 during the 1992 spring and

summer sampling periods ................................................ 21

Table 14. Locations in Pool 26 where species were present during the 1992 spring and summer

sampling periods ....................................................... 21

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

during the 1992 spring and summer sampling periods ........................... 22

Table 16. Locations in La Grange Pool, Illinois River, where species were present during the 1992

spring and summer sampling periods ........................................ 23
v

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 1992 (Pools 4, 8, 13,

26, and La Grange Pool) .................................................. 3

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1992 monitoring of submersed

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

Figure 3. Pool 8, Upper Mississippi River, transect locations for the 1992 monitoring of submersed

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

Figure 4. Pool 13, Upper Mississippi River, transect locations for the 1992 monitoring of submersed

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

Figure 5. Pool 26, Upper Mississippi River, transect locations for the 1992 monitoring of submersed

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

Figure 6. La Grange Pool, Illinois River, transect locations for the 1992 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

1992 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 1992,

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 1992. This

report was developed with funding provided by the Long Term Resource Monitoring Program.
1992 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, Heidi Langrehr, John Nelson,

and Susan Romano-Pietzmeyer

Abstract

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

Monitoring Program. This report summarizes the 1992 effort of monitoring submersed aquatic vegetation (SAV)

along transects permanently established in vegetated locations within four navigation pools of the Upper

Mississippi River and one navigation pool of the Illinois River. More species of submersed aquatic macrophytes

were found along transects in lower Pool 4 than in any other reach. La Grange Pool and Pool 26 transects had the

fewest species. Across all pools, sago pondweed (Potamogeton pectinatus) and coon's tail (Ceratophyllum

demersum) were the species most frequently found. Several species of SAV were seasonally dynamic at the

transect locations, with changes in frequencies especially common among sago and curly (P. crispus), and species

of narrow-leaved pondweeds. Many of the species in Pools 8 and 13 increased in frequencies between sampling

periods, resulting in a significantly higher proportion of sites with SAV by the summer sampling period.

Although frequencies of individual species changed during the growing season in Pools 4 and 26 and La Grange

Pool, the proportion of sites with SAV remained stable. Community diversity within each pool was similar

between sampling periods except in Pool 13 where diversity increased at most locations during the season.

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 provide a baseline of information to which

future observations can be compared. In combination with other component 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 1992. This report also provides an initial indication of features of submersed aquatic vegetation

(SAV) that can be compared to future monitoring efforts.

Submersed macrophytes have always played an important role in the UMRS ecosystem. These plant

communities provide food for migratory waterfowl (Korschgen et. al. 1988) and improve the 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 following 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, U.S. Fish and Wildlife Service, Winona, Minnesota, unpublished

data; C. Korschgen, Northern Prairie Wildlife Research Center, Jamestown, North Dakota, unpublished data;
2

J. Lyons, U.S. Fish and Wildlife Service, McGregor, Iowa, personal communication; R. Anderson, Western

Illinois University, Macomb, personal 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. During the 1950s, SAV in much of the river rapidly disappeared and

only remnant populations now survive (Talkington and Semonin 1991).

Long-term monitoring can increase 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 1992 growing season was the second 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 presence and 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 significance each

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

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] 752–797), Pool 8 (M679–703), Pool 13 (M523–557), Pool

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

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

the confluence of the Mississippi and Illinois Rivers.

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

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

complex with numerous backwaters and 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.

A low percentage of the total aquatic area is composed of contiguous backwaters, and commensurately, a

high percentage is composed of the main channel. La Grange Pool is similar to Pool 26 in floodplain
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 1992

(Pools 4, 8, 13, 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.

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.

During 1992, monitoring was 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 (Appendix A). 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, Peterson Lake, and Lower Peterson Lake. We also

monitored Rice Lake and Big Lake Bay, part of the Big Lake area.
4

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1992 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 1992 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

d

channel and main channel border areas.

Aquatic vegetation includes rooted floating aquatics and emergents only. e
5

Figure 3. Pool 8, Upper Mississippi River,

transect locations for the 1992 monitoring of

submersed aquatic vegetation for the Long

Term Resource Monitoring Program.

Figure 4. Pool 13, Upper Mississippi River, transect

locations for the 1992 monitoring of submersed aquatic

vegetation for the Long Term Resource Monitoring

Program.

In Pool 8, we sampled SAV for the second year at five locations including Target Lake, Lawrence Lake,

a backwater area near Goose Island, Shady Maple, and the interior of Horseshoe Island, which is the site of

of one of the U.S. Army Corps of Engineers Habitat Rehabilitation and Enhancement Projects (Figure 3).

An additional set of transects was added at a small isolated backwater near Stoddard, Wisconsin

(Appendix A). 

In Pool 13, we sampled SAV at seven locations (Figure 4). All locations were selected the previous year

and were distributed primarily in the middle and lower portions of the pool. 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 1992 monitoring of

submersed aquatic vegetation for the Long Term Resource Monitoring Program.

In Pool 26, we sampled SAV for the second year at three vegetated backwater locations (Figure 5).

Transect locations were distributed in Swan Lake, Stump Lake, and in the Calhoun Point area, which consists

of several backwater lakes, sloughs, and wet-weather ponds (Appendix A). The Illinois Department of

Natural Resources manages the Stump Lake and Calhoun Point areas and uses control structures and

pumping to drain these areas for waterfowl management. Fuller Lake, at the northern end of Swan Lake, was

added to the monitoring in 1992.

In La Grange Pool, we sampled SAV for the second year at three backwater locations including Point

Lake, Spring Lake, and Banner Marsh (Figure 6). The three backwaters are among the few locations where

submersed vegetation can still be found within this river reach. These backwaters are classified as isolated

and are protected from the main stem of the Illinois River by agricultural levees. However, Point Lake often

receives overflow water from the main channel of the Illinois River. Banner Marsh (Bulrush Pond) and

Spring Lake are actively managed for fishing and are completely isolated. A fourth monitoring site, a channel

border near Grape Island, was added in 1992.

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 in the middle portion, and four in the lower portion. We did no sampling in the areas

between the groups.
7

Figure 6. La Grange Pool, Illinois River, transect locations for the 1992 monitoring of

submersed aquatic vegetation for the Long Term Resource Monitoring Program.

In most transect locations, sampling was performed twice during the growing season to observe seasonal

changes in species composition and relative frequencies (Appendix A). In Pool 8, the Stoddard backwater

was first monitored during the summer sampling period of 1992, and in Pool 26, Stump and Fuller Lakes

were only sampled during spring because of low water levels by summer. Sampling dates for each pool

location and for each sampling period are listed in Appendix A.

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 divided into three equal portions. We sampled plants once in 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 submersed species on the rake were identified and recorded. After all three casts were 2

made, each species recovered was assigned a rating from 1 to 4—instead of from 1 to 5 as 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% visible vegetative cover within the sample area, 26–50%, 51–75%, and 76–100%). Floatingleaved species are listed in the taxa list (Appendix B), but not included in the analysis. 

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 found in

Table 2.

If a species was not collected during the 1991 season, 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.

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 Northern watermilfoil , Myriophyllum sibiricum Komarov b

shortspike watermilfoil

Haloragaceae Eurasian watermilfoil , spike watermilfoil Myriophyllum spicatum L. b

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 Yellow pondlily Nuphar lutea (L.) Sm.

Nymphaeaceae White waterlily Nymphaea odorata Ait.

Onagraceae Floating primrosewillow Jussiaea repens L.
Table 2. Continued.

Family Common name Scientific name a,b a

9

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

grassleaf mudplantain

Potamogetonaceae Curly pondweed, curlyleaf pondweed Potamogeton crispus L.

Potamogetonaceae Flatstem pondweed Potamogeton zosteriformis Fern.

Potamogetonaceae Illinois pondweed Potamogeton illinoisensis Morong.

Potamogetonaceae River pondweed , longleaf pondweed Potamogeton nodosus Poir b

Potamogetonaceae Leafy pondweed Potamogeton foliosus Raf.

Potamogetonaceae Variableleaf pondweed Potamogeton gramineus L.

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.

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.

Environmental Factors

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

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

four broad categories and subsequently condensed into three 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 f = j /n where j = number of sample sites containing species i

i i 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 i i i

all species. To test for significant changes in frequencies for a species between the two sampling periods,

a value for Z was calculated with the following formula:
10

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.

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

but 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 vegetated with SAV are generally scarce in those two

pools.

Results and Discussion

All Pools

During 1992, we found 16 species of submersed aquatic plants along transects across study pools. Two

of the species found are macroalgae belonging to the muskgrass family (Characeae). We also found four

species of floating-leaved plants and have included them in our species list (Appendix B). The most

submersed aquatic species found at transect sites during a sampling period was 14 (Pool 4 during summer

sampling), and the least was five (Pool 8 during spring sampling). Coon’s tail, sago pondweed, and curly

pondweed were the only species sampled in every study pool during both spring and summer sampling.

Eurasian watermilfoil, found in four of the five pools, was also a prevalent species, reaching high frequencies

in La Grange Pool and Pool 8. Eurasian watermilfoil, for reasons unknown to us, has not been found in

Pool 26. Wild celery was most common in Pools 4 and 13, was present at a frequency less than 1% in Pool

8, and was not found in Pool 26 or La Grange Pool. Many species remained at frequencies less than 10%

throughout all pools (Table 3).
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 1992.a

Spring Summer

4 8 13 26 LG 4 8 13 26 LG

Species q freq q freq q freq q freq q freq q freq q freq q freq q freq q freq

Fre Rel Fre Rel Fre Rel Fre Rel Fre Rel Fre Rel Fre Rel Fre Rel Fre Rel Fre Rel

Canadian waterweed 5.4 4.8 – – – – 0.7 0.3 – – 8.8 8.7 – – 1.8 1.3 0.7 0.3 – – 

Chara – – – – – – – – 5.1 3.8 <0.1 0.1 – – 0.3 0.2 – – 8.3 7.3 b 

Coon's tail 19.5 20.8 2.0 3.4 6.3 5.6 31.7 34.9 17.6 12.2 15.6 19.0 8.8 10.8 24.3 17.9 33.2 34.8 21.2 21.3

Curly pondweed 19.4 24.8 20.8 51.3 8.4 8.4 17.8 16.1 35.3 22.3 2.5 2.0 16.6 23.8 8.9 5.4 4.5 1.8 6.1 3.6

Eurasian watermilfoil 4.4 4.2 9.4 16.5 0.5 0.5 – – 69.8 56.2 6.3 5.5 19.8 24.0 11.6 7.3 – – 56.8 62.2

Flatstem pondweed 2.4 1.9 – – 0.1 0.1 – – – – 3.6 2.6 0.4 0.5 10.4 8.7 – – – – 

c

Horned pondweed – – 0.4 0.6 – – – – – – 0.5 0.5 – – – – – – – – 

d

Longleaf pondweed 1.0 1.0 – – 2.0 2.3 0.2 0.2 2.9 1.3 0.9 0.7 0.4 0.4 5.7 3.7 – – 3.8 2.4

Nitella – – – – – – – – – – <0.1 0.1 – – – – – – – – 

Nodding waternymph – – – – – – – – – – 0.8 1.1 1.6 2.2 3.3 2.1 – – – – 

Sago pondweed 28.3 38.7 16.3 28.1 49.2 81.9 46.2 41.4 7.3 3.3 16.1 16.3 28.3 37.4 53.6 47.9 54.2 58.7 3.0 0.3

Small and leafy pondweeds 1.2 0.8 – – – – 10.3 7.0 <0.1 0.2 4.3 4.1 – – 0.2 0.1 7.1 3.2 – – 

Southern waternymph – – – – – – – – – – – – 0.1 0.1 1.5 0.8 1.4 1.2 – – 

Water stargrass 1.7 1.2 – – p p – – – – 9.5 9.1 0.5 0.5 ? ? – – – – 

d c c

Western waterweed – – – – – – – – 2.2 0.7 – – – – – – – – 4.5 2.8 e

Wild celery 2.2 1.7 – – 1.1 1.1 – – – – 22.3 30.2 0.1 0.2 6.6 4.6 – – – – 

Data are based on all transect locations that were sampled during both sampling periods within a pool. Rounding may cause relative

a

frequency columns to not total 100%.

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

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

Horned pondweed and water stargrass were found in Pool 26 in a backwater that was not included in this analysis. d

Verification of specimen needed for positive identification. e

Relative frequencies revealed interesting patterns. In Pools 4, 8, 13, and 26, coon's tail, sago pondweed,

and curly pondweed represented more than 80% of the relative frequencies during spring sampling. By

summer sampling, a somewhat more balanced distribution was observed in two pools. In Pool 4, several

species, including coon's tail, Canadian waterweed, Eurasian watermilfoil, sago pondweed, small and leafy

pondweeds, water stargrass, and wild celery, contributed to more than 90% of the relative frequencies. In

Pool 13, Eurasian watermilfoil, flatstem pondweed (or water stargrass), coon's tail, and sago pondweed

represented more than 80% of the relative frequencies. In Pool 8, however, more than 70% of the relative

frequencies were still shared by coon's tail, curly pondweed, and sago pondweed. Also, in Pool 26, coon's

tail and sago pondweed remained the dominant species during the summer sampling period with more than
12

90% of the relative frequencies. The relative frequency of Eurasian watermilfoil was more than 50% in both

spring and summer in La Grange Pool. In all pools, curly pondweed dropped in relative frequency, sometimes

as much as 90%, between spring and summer sampling periods. The biggest change occurred in Pool 8,

where it dropped from 51.6 (its highest relative frequency) to 23.8%, and in Pool 4 where it dropped from

24.8 to 2% (Table 3).

The proportion of sites with SAV to the total number of sampling sites increased significantly (based on

Chi-square tests) in Pools 8 and 13, but remained similar in Pools 4 and 26 and La Grange Pool (Table 4).

In Pool 4, some species increased in frequency while others decreased, thus the proportion of sites with SAV

did not change significantly between the spring and summer sampling periods. In Pools 8 and 13, increases

in frequencies of several species over the sampling season were great enough to significantly influence the

proportion of sites vegetated with submersed species. The frequency of most species in Pool 26 and

La Grange Pool did not change significantly between spring and summer sampling periods, thus, the

proportion of vegetated sites was not significantly different between spring and summer.

Table 4. Proportion of sites with submersed aquatic vegetation

to the total number of sites sampled at transect locations

during the 1992 spring and summer sampling periods.

Location Spring Summer 

Pool 4 54.2 50.1 (p > 0.900)a

Pool 8 42.3 53.3 (p < 0.001)

Pool 13 58.4 72.2 (p <. 0.001)

Pool 26 78.6 85.6 (p > 0.800)

La Grange Pool 86.8 83.9 (p > 0.420)

Probability values for differences between sampling periods are given

a

in parentheses. P-values are based on Chi-square tests with a 0.05

level of significance.

The proportion of sites with submersed vegetation at our transect locations in La Grange Pool and in

Pool 26 was relatively high compared to other pools. The backwaters where transects are located are small

and protected by levees from the main channel of the Illinois River and most are managed for fishing or

waterfowl hunting. Thus, SAV tends to cover the water surfaces, at least during years when flooding does

not occur.

Water Depths and Substrates

Mean water depths at transect sites where submersed aquatic plants grew were from 0.3 m in Pool 26

during summer sampling to 1.3 m in La Grange Pool during spring sampling (Table 5). La Grange Pool,

where transects are located in backwaters that are protected from high turbidity levels of the Illinois River

main channel, was the only pool where water depths reached more than 1 m.
13

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 1992 spring and summer transect

sampling periods.

Location spring sampling deviation N summer sampling deviation N

Mean depth Standard Mean depth Standard

Pool 4 0.7 0.4 733 0.7 0.3 776

Pool 8 0.7 0.3 322 0.5 0.3 778

Pool 13 0.6 0.2 547 0.7 0.3 1,138

Pool 26 0.5 0.1 985 0.3 0.2 495

La Grange Pool 1.3 0.5 194 1.2 0.5 138

Generally, SAV was present mostly on silt and silt-sand substrates throughout all pools. Pools 4 and 13

also reported sand substrates along transects with SAV, reflecting a broader range of habitat types monitored

within those pools compared to the others (Table 6).

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

vegetation during the 1992 spring and summer sampling periods. 

Pool

Substrate type 4 8 13 26 La Grange

Silt/clay 75.0 92.2 71.8 100 71.9

Mostly silt with sand 20.8 7.8 19.3 – 28.1 a

Mostly sand with silt 4.2 – 8.9 – –

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

Pool 4

We found 10 species of SAV along Pool 4 transects during the first sampling period and 14 during the

second sampling period (Table 7). No additional species were found during informal surveys that were not

found along transects. More species were found along transects in lower Pool 4 (below Lake Pepin) than

along transects in the upper pool (above Lake Pepin; Appendix B). Coon's tail, sago pondweed, and curly

pondweed had the highest frenquencies during the spring sampling period and contributed to more than 70%

of the relative frequencies. These three species contributed to more than 70% of the relative frequencies.

Curly pondweed declined from nearly 20% frequency to less than 3% between sampling periods; this decline

was not unexpected as the species is a "cool season strategist" and typically completes its annual cycle early

in the growing season (Nichols and Shaw 1986). Sago pondweed and coon's tail also declined, but to a lesser

degree (Table 7).

Most species, with the exception of sago pondweed, coon's tail, and curly pondweed, were present at

frequencies less than 10% during the spring sampling, but showed increases by the summer sampling period.
14

Wild celery increased from less than 3% to greater than 20%, thus becoming the dominant species by the

summer sampling period. Wild celery, coon's tail, and sago pondweed contributed to greater than 50% of the

relative frequencies during the summer sampling period. Species with frequencies remaining less than 2%

during the season included longleaf pondweed and species of small stature such as chara, nitella, and nodding

waternymph (Table 7).

Table 7. Frequencies and relative (%) frequencies of species in Pool 4 during the 1992 spring and summer sampling

periods.

Species

Frequencies Relative frequencies a a

Spring Summer Spring Summer

Coon's tail 19.5 15.6 20.8 19.0

Curly pondweed 19.4 2.5 24.8 2.0

Canadian waterweed 5.4 8.8 4.8 8.7

Eurasian watermilfoil 4.4 6.3 4.2 5.5

Flatstem pondweed 2.4 3.6 1.9 2.6

Longleaf pondweed 1.0 0.9 1.0 0.7

Nodding waternymph – 0.8 – 1.1 b

Sago pondweed 28.3 16.1 38.7 16.3

Small and leafy pondweeds 1.2 4.3 0.8 4.1

Water stargrass 1.7 9.5 1.2 9.1

Wild celery 2.2 22.3 1.7 30.2

Other species – 0.7 – 0.7 c

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 species was not found. b

Other species include horned pondweed, chara, and nitella.

c

Although most species remained at similar frequencies at most locations, sago and curly pondweeds

decreased at many locations during the season, whereas wild celery and water stargrass increased at several

locations. Several species including Canadian waterweed, Eurasian watermilfoil, flatstem pondweed, small

and leafy pondweeds, water stargrass, and wild celery significantly increased in Robinson Lake. Water

stargrass and wild celery also increased significantly in Big Lake and Peterson Lake (Table 8).

Most species were distributed throughout transect locations in lower Pool 4. Chara and nitella, however,

were found only in the Big Lake area. Horned pondweed was found only in Robinson Lake. Species found

in upper Pool 4 include curly pondweed, Eurasian watermilfoil, flatstem pondweed, longleaf pondweed, and

sago pondweed (Table 8). Community diversity was highest in lower pool locations (Appendix C).
15

Table 8. Locations in Pool 4 where species were present during the 1992 spring and summer sampling periods. 

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

Canadian waterweed Peterson Lake (lower) Robinson Lake 

Big Lake

Big Lake Bay

Rice Lake

Peterson Lake (upper, middle)

Chara Big Lake

Big Lake Bay

Coon's tail Big Lake Lower Peterson Lake 

Peterson Lake Rice Lake

Big Lake Bay

Robinson Lake

Curly pondweed Lower Peterson Lake Big Lake Bay

Big Lake Bay City Flats 

Robinson Lake Goose Lake

Peterson Lake Dead Slough Lake

Eurasian watermilfoil Big Lake Robinson Lake

Big Lake Bay

Lower Peterson Lake 

Bay City Flats

Rice Lake

Peterson Lake

Flatstem pondweed Peterson Lake Robinson Lake

Big Lake

Big Lake Bay 

Mud Lake

Horned pondweed Robinson Lake

Longleaf pondweed Peterson Lake

Big Lake

Robinson Lake

Bay City Flats

Dead Slough Lake

Nitella Big Lake

Nodding waternymph Big Lake Bay

Robinson Lake

Rice Lake

Big Lake

Sago pondweed Big Lake Peterson Lake

Robinson Lake Rice Lake

Bay City Flats Goose Lake

Dead Slough Lake Mud Lake

Lower Peterson Lake 

Big Lake Bay
Table 8. Continued.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

16

Small and leafy Big Lake Robinson Lake

pondweeds Lower Peterson Lake

Big Lake Bay

Rice Lake

Peterson Lake

Water stargrass Peterson Lake Robinson Lake

Big Lake Bay Big Lake

Robinson Lake Lower Peterson Lake 

Wild celery Big Lake Bay Robinson Lake

Rice Lake Lower Peterson Lake

Big Lake

Peterson 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 five species of SAV along Pool 8 transects during the spring sampling period and 11 at the

same transect locations during the summer sampling period. Curly pondweed and sago pondweed were the

only two species with frequencies greater than 10% during the spring sampling period, accounting for nearly

80% of the relative frequencies during that sampling period. By the summer sampling period, curly

pondweed dropped in frequency and relative frequency, yet remained third highest in relative frequency.

Sago pondweed and Eurasian watermilfoil increased in frequency between spring and summer sampling.

Common bladderwort,flatstem pondweed, longleaf pondweed, nodding waternymph, southern waternymph,

water stargrass, and wild celery were not found until the summer sampling period. All these species,

however, remained at frequencies less than 2%, thus contributing to less than 5% of the total relative

frequencies for the summer sampling period (Table 9).

Significant increases in species frequencies occurred at several locations between spring and summer

sampling. Coon's tail and sago pondweed, which had decreased during the 1991 season, increased during the

1992 season, especially in Lawrence Lake. Eurasian watermilfoil increased at two locations, Horseshoe

Island and Lawrence Lake, and curly pondweed increased at Lawrence Lake. No species significantly

decreased at any location and several species did not change during the season (Table 10). 

Mostspecies were distributed in at least two transect locations, except for common bladderwort, southern

waternymph, and wild celery, which were found only at Lawrence Lake. Horned pondweed was found only

at Horseshoe Island (Table 10). Community diversity increased at several locations between spring and

summer sampling, especially in Lawrence Lake, Goose Island, and Target Lake (Appendix C). 
17

Table 9. Frequencies and relative (%) frequencies of species in Pool 8 during the 1992 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Coon's tail 2.0 8.8 3.4 10.8

Common bladderwort – 0.1 – 0.1 b

Curly pondweed 20.8 16.6 51.3 23.8

Eurasian watermilfoil 9.4 19.8 16.5 24.0

Flatstem pondweed – 0.4 – 0.5

Horned pondweed 0.4 – 0.6 –

Longleaf pondweed – 0.4 – 0.4

Nodding waternymph – 1.6 – 2.2

Sago pondweed 16.3 28.3 28.1 37.4

Southern waternymph – 0.1 – 0.1

Water stargrass – 0.5 – 0.5

Wild celery – 0.1 – 0.2

Frequencies and relative frequencies are based collectively on all transect locations sampled during both sampling periods pooled a

together.

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

Table 10. Locations in Pool 8 where species were present during the 1992 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

Common bladderwort Lawrence Lake

Coon's tail Shady Maple Lawrence Lake

Target Lake

Goose Island

Curly pondweed Horseshoe Island Lawrence Lake

Shady Maple

Goose Island

Eurasian watermilfoil Shady Maple Horseshoe Island

Target Lake Lawrence Lake

Goose Island

Flatstem pondweed Lawrence Lake

Goose Island

Horned pondweed Horseshoe Island
Table 10. Continued.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

18

Longleaf pondweed Shady Maple

Goose Island

Target Lake

Nodding waternymph Horseshoe Island

Goose Island

Target Lake 

Lawrence Lake

Sago pondweed Shady Maple Horseshoe Island

Goose Island Lawrence Lake

Target Lake

Southern waternymph Lawrence Lake

Water stargrass Horseshoe Island

Lawrence Lake

Shady Maple

Wild celery 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 seven species along Pool 13 transects during the 1992 spring sampling period and 12 during

the summer sampling period (Appendix B). No species were found during the informal surveys that were not

found at transect locations. Flatstem pondweed and water stargrass were probably both present, which would

add one species to the count for each sampling period, but we did not distinguish between the two species

while in the field. During spring sampling, sago pondweed was the only species with a frequency more than

10%. Most species, however, showed increases in frequencies between sampling periods, especially coon's

tail (increasing from 6% to more than 20%), Eurasian watermilfoil (increasing from less than 1% to more

than 10%), and flatstem pondweed (or water stargrass; increasing from less than 1% to more than 10%).

Species not present during spring sampling but present during summer sampling included Canadian

waterweed, chara, nodding waternymph, small and leafy pondweeds, and southern waternymph. These

species, however, remained at individual frequencies less than 3% and contributed to less than 5% of the total

relative frequencies for the summer sampling period. Sago pondweed remained the species with the highest

relative frequency during both sampling periods, dominating relative frequencies at 81.9% during spring

sampling and still dominating relative frequencies during summer sampling at nearly 50% (Table 11). 

Most species had significant increases in frequencies at some locations during the 1992 growing season.

The only decreases observed were sago pondweed which decreased at Johnson Creek Levee, and curly

pondweed, which decreased in Brown's Lake (Table 12). Most species were found at several transect

locations, except for small and leafy pondweeds, which were found only at Pomme de Terre, and nodding

waternymph and chara, which were found only at the Johnson Creek locations. Community diversity

increased at most transect locations between sampling periods (Appendix C).
19

Table 11. Frequencies and relative frequencies (%) of species in Pool 13 during the 1992 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed – 1.8 – 1.3 b

Chara – 0.3 – 0.2

Coon's tail 6.0 24.3 5.6 17.9

Curly pondweed 8.4 8.9 8.4 5.4

Eurasian watermilfoil 0.5 11.6 0.5 7.3

Longleaf pondweed 2.0 5.7 2.3 3.7

Nodding waternymph – 3.3 – 2.1

Sago pondweed 49.2 53.6 81.9 48.0

Small and leafy pondweeds – 0.2 – 0.1

Southern waternymph – 1.5 – 0.8

Wild celery 1.1 6.6 1.1 4.6

Other species 0.1 10.4 0.1 8.7 c

Frequencies and relative frequencies are based collectively on all transect locations pooled together. a

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

Other species include water stargrass and flatstem pondweed. c

Table 12. Locations in Pool 13 where species were present during the 1992 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

Canadian waterweed Spring Lake Johnson Creek 

Pomme de Terre Johnson Creek Levee

Chara Johnson Creek

Coon's tail Brown's Lake Johnson Creek

Johnson Creek Levee

Pomme de Terre

Spring Lake

Savanna Bay 

Curly pondweed Brown's Lake Potter's Marsh

Johnson Creek

Johnson Creek Levee

Spring Lake

Savanna Bay

Pomme de Terre

Brown's Lake
Table 12. Continued.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

20

Eurasian watermilfoil Savanna Bay Johnson Creek

Potter's Marsh Johnson Creek Levee

Spring Lake Pomme de Terre

Flatstem Pomme de Terre Johnson Creek

pondweed/water Brown's Lake Johnson Creek Levee

stargrass Savanna Bay

Spring Lake 

Potter's Marsh

Longleaf pondweed Brown's Lake Johnson Creek

Savanna Bay Johnson Creek Levee

Pomme de Terre

Nodding waternymph Pomme de Terre Johnson Creek

Johnson Creek

Johnson Creek Levee

Spring Lake

Savanna Bay

Sago pondweed Johnson Creek Brown's Lake Brown's Lake 

Johnson Creek Levee Savanna Bay Spring Lake

Potter's Marsh

Pomme de Terre

Small and leafy Pomme de Terre

pondweeds

Southern waternymph Johnson Creek

Johnson Creek Levee

Wild celery Pomme de Terre Johnson Creek

Potter's Marsh Johnson Creek Levee

Spring Lake 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

Pool 26

We found six species of SAV along Pool 26 transects during the spring and summer sampling periods.

Two additional species, horned pondweed and water stargrass, were found at low frequencies in Fuller and

Stump Lakes during the spring sampling (Fuller and Stump Lakes were only sampled during spring and are

not included in Table 13). Frequencies and relative frequencies were dominated by coon's tail, sago

pondweed, and curly pondweed during spring sampling and by coon's tail and sago pondweed during summer

sampling with sago pondweed owning the highest relative frequency during both periods. Small and leafy

pondweeds and curly pondweed reached highest frequencies during the spring. Canadian waterweed, longleaf

pondweed, and southern waternymph were found rarely (less than 2%; Table 13).
21

Table 13. Frequencies and relative frequencies (%) of species in Pool 26 during the 1992 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 0.7 0.7 0.3 0.3

Coon's tail 31.7 33.2 34.9 34.8

Curly pondweed 17.8 4.5 16.1 1.8

Longleaf pondweed 0.2 – 0.2 –

b

Sago pondweed 46.2 54.2 41.4 58.7

Small and leafy pondweeds 10.3 7.1 7.0 3.2

Southern waternymph – 1.4 – 1.2

Frequencies and relative frequencies are based on two locations pooled together; Calhoun Point and Swan Lake. a

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

Curly pondweed and small and leafy pondweeds decreased significantly during the growing season at

Calhoun Point. An increase in both sago pondweed occurred in Swan Lake (Table 14). Community diversity

was highest in Fuller and Stump Lakes during spring sampling (Appendix C).

Table 14. Locations in Pool 26 where species were present during the 1992 spring and summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

Canadian waterweed Calhoun Point 

Coon's tail Calhoun Point

Swan Lake

Curly pondweed Calhoun Point Swan Lake

Longleaf pondweed Stump Lake

Calhoun Point

Sago pondweed Calhoun Point Swan Lake

Small and leafy Calhoun Point 

pondweeds

Southern waternymph 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
22

La Grange Pool

We found eight species of submersed aquatic macrophytes along La Grange Pool transects during the

1992 spring sampling period, and seven during the summer period. Species frequencies in La Grange Pool

were dominated by Eurasian watermilfoil, coon's tail, and curly pondweed in spring, reaching a combined

relative frequency of more than 90%. By summer sampling, curly pondweed had dropped to less than 7%

frequency, and Eurasian watermilfoil (61.6%) and sago pondweed (21.1%) dominated the relative

frequencies. Eurasian watermilfoil has been a problem species in Spring Lake, covering most the water

surface in the lower portion where transects are located. Frequencies of Eurasian watermilfoil typically

occupied at least 80% of all sites sampled. Coon's tail dominated at Point Lake, a location where Eurasian

watermilfoil has not been found. Relative frequencies reflect the high frequencies of Eurasian watermilfoil

and coon's tail. La Grange Pool backwaters are the only locations within our study areas where we found

western waterweed, although positive identification by an expert is still needed (Table 15). Community

diversity increased at Bulrush Pond, but decreased at Spring Lake and Point Lake between sampling periods

(Appendix C).

Table 15. Frequencies and relative frequencies (%) of species in La Grange Pool, Illinois River, during the 1992 spring

and summer sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Chara 5.1 8.3 3.8 7.3

Coon's tail 17.6 21.2 12.2 21.1

Curly pondweed 35.3 6.1 22.3 3.4

Eurasian watermilfoil 69.8 56.8 56.2 61.6

Longleaf pondweed 2.9 3.8 1.3 2.4

Sago pondweed 7.3 3.0 3.3 1.4

Small and leafy pondweeds <0.1 – 0.2 –

b

Western waterweed 2.2 4.5 0.7 2.8

Frequencies and relative frequencies are based on all transect locations pooled together. a

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

Only two species had significant change in frequency between sampling periods; Eurasian watermilfoil

declined in Spring Lake and Bulrush Pond and curly pondweed declined in Spring Lake. Coon's tail and sago

pondweed were found at all locations, whereas curly pondweed, western waterweed, and chara were found

only in Spring Lake (Table 16).
23

Table 16. Locations in La Grange Pool, Illinois River, where species were present during the 1992 spring and

summer sampling periods.

Species sampling periods sampling periods sampling periods

Decreased in frequency No change between Increased in frequency

between spring and summer spring and summer between spring and summer

a b a

Chara Spring Lake

Coon's tail Point Lake

Spring Lake

Bulrush Pond

Curly pondweed Spring Lake

Eurasian watermilfoil Spring Lake

Bulrush Pond

Longleaf pondweed Bulrush Pond

Sago pondweed Point Lake

Bulrush Pond

Spring Lake

Grape Island

Western waterweed 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

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.

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Myriophyllum spicatum, Potamogeton crispus, and Elodea canadensis. Hydrobiologia 131:3–21.

Peck, J. H., and M. M. Smart. 1986. An assessment of the aquatic and wetland vegetation of the Upper

Mississippi River. Hydrobiologia 136:57–76.

Talkington, L. M., and R. G. Semonin. 1991. The Illinois River: Working for our state. Miscellaneous

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

U.S. Fish and Wildlife Service. 1993. Operating Plan for the Upper Mississippi River System Long Term

Resource Monitoring Program. Environmental management Technical Center, Onalaska, Wisconsin,

Revised September 1993. EMTC 91-P002R. 179 pp. (NTIS #PB94-160199)
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 1992 Sampling Season

Location transects in spring summer spring summer sites (m)

Number of sites of sites in sampled in sampled in between 

Number Number Dates Dates Distance 

Pool 4

Dead Slough Lake 9 130 129 6/9–11 7/30–31; 8/3 30

(M789.2, M788.5,

M788.0)a

Goose Lake 3 26 23 6/4 7/27 30

(M788.G)b

Mud Lake 3 55 56 6/4 7/29 30

(M791.3)

Bay City Flats 3 76 76 6/11–12 8/13 30

(Catherine Pass ; M787.0) c

Robinson Lake 9 198 168 5/21, 26–28 7/20–21, 23 30

(M758.R)b

Big Lake Bay 3 32 27 5/28 7/24 30

(M758.5)

Rice Lake 3 26 28 6/1 7/27 30

(M758.0)

Big Lake 5 133 123 6/1–3 7/27–28 30

(M757.5)

Peterson Lake 6 71 51 5/14–15, 19 7/15 30

(M754.8, M754.5)

Lower Peterson Lake 4 109 156 5/20–21 7/16–17 30

(M753.5)

Total Pool 4 48 856 837 22 19

Pool 8

Target Lake 7 (spring) 105 259 5/12, 14; 8/05–6, 10 15

(M696.0) 11 (summer) 6/17

Goose Island 5 111 113 5/13; 6/3 7/27, 29 15

(M692.0)

Lawrence Lake 6 (spring) 261 398 5/18–19, 21; 7/28, 31; 15

(M691.0) 10 (summer) 6/9, 11–12 8/12–14,

17–19
Location transects in spring summer spring summer sites (m)

Number of sites of sites in sampled in sampled in between 

Number Number Dates Dates Distance 

A-2

Shady Maple 3 106 105 6/2, 8 8/20, 26 15

(M690.0)

Horseshoe HREP 5 75 83 6/5, 19 8/11, 19 15 d

(M687.0)

Stoddard 4 (summer) not 47 not 8/25, 27 15

(M684.0) sampled sampled

Total Pool 8 26 (spring) 658 1,005 17 21

38 (summer)

Pool 13

Brown's Lake 25 280 354 6/05, 8–11 7/16–17, 15 and 30

(M545.1, M544.5) 20–21, 23,

27

Savanna Bay 12 146 148 5/26–27, 29 7/28, 31; 8/3 15

(M541.5, M540.5,

M539.5)

Spring Lake 12 126 136 5/29; 6/3, 5 7/29; 8/4, 5 15

(M534.8, M533.6,

M532.0)

Pomme de Terre 5 69 81 5/22 8/6 15

(M526.0)

Potter's Marsh 6 71 41 5/19 8/11, 13 15

(M524.0)

Johnson Creek Levee 4 81 73 6/12 8/13–14 15

(M523.5)

Lower Johnson Creek 2 40 56 5/20 8/12 15

(M523.0)

Total Pool 13 66 813 889 18 20

Pool 26

Calhoun Point 21 157 157 5/28; 6/1, 3 7/20, 23 15

(I003.0)e,f

Swan Lake (I005.5) 11 (spring) 291 282 5/20–21, 7/15–16 15

3 (summer) 26–27

Stump Lake 8 (spring) 200 not 6/8–9 not 15

(I010.0, I011.5) sampled sampled

Total Pool 26 40 (spring) 648 439 10 4

32 (summer)
Location transects in spring summer spring summer sites (m)

Number of sites of sites in sampled in sampled in between 

Number Number Dates Dates Distance 

A-3

La Grange Pool

Point Lake 6 20 21 5/20 8/4 15

(I100.0)e

Spring Lake 5 87 85 5/18, 28–29; 7/22–23, 28; 15

(I135.5) 6/4, 9–10 8/3, 10

Bulrush Pond 2 16 16 6/11 8/11 15

(I140.7)

Grape Island 3 13 9 5/22; 6/3 7/24 15

(I086.4)

Total La Grange Pool 11 136 132 8 7

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

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

Locally recognized name. c

Habitat Rehabilitation and Enhancement Project. d

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

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

are managed by the Illinois Department of Natural Resources, and are designated 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

(Elodea canadensis L.) x – x x –

Chara (Chara spp.) x – x – x

Common bladderwort – x – – –

(Utricularia macrorhiza L.) 

Coon's tail

(Ceratophyllum demersum L.) x x x x x

Curly pondweed

(Potamogeton crispus L.) x x x x x

Eurasian watermilfoil lower pool only

(Myriophyllum spicatum L.) x x x – x

b c

Flatstem pondweed lower pool only

(Potamogeton zosteriformis Fern) x x x – –

d

Horned pondweed lower pool only

(Zannichellia palustris L.) x x – x –

Longleaf pondweed

(Potamogeton nodosus Poiret.) x x x x x

Nitella (Nitella spp.) x – – – –

Nodding waternymph lower pool only

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

Schmidt) 

Sago pondweed

(Potamogeton pectinatus L.) x x x x x

Small and leafy pondweeds lower pool only

(Potamogeton pusillus and x – x x x

P. foliosus L.)

Southern waternymph

(Najas guadalupensis [Spreng.] – x x x –

Magnus)

Water stargrass lower pool only

(Heteranthera dubia L.) x x x x –

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 lower pool only

(Vallisneria americana Michx.) x x x – –

Floating-leaved Species

American lotus x x x – x

(Nelumbo lutea [Willd.] Pers.)

White waterlily x x – – –

(Nymphaea odorata Ait.)

Yellow pondlily – x – – –

(Nuphar lutea [L.] Sm.)

Total per pool 16 15 14 9 9

e

In Pool 4, species were found in both upper and lower pools unless otherwise indicated. a

The symbol “x” indicates the species was present during at least one sampling period. b

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

Flatstem pondweed and water stargrass are listed as both present in Pool 13 but no distinction was made between the two species d

when sampled in the field.

Total per pool is the total number of species present regardless of sampling period. e
C-1

Appendix C

Location and Community Diversity for Spring and Summer Sampling Periods

Location Spring sample diversity Summer sample diversity a a

Pool 4

 Lower Peterson Lake 0.74 0.62

 Peterson Lake 0.75 0.72

 Big Lake 0.81 0.47

 Rice Lake 0.60 0.63

 Big Lake Bay 0.64 0.77

 Robinson Lake 0.71 0.82

 Bay City Flats 0.00 0.03

 Dead Slough Lake 0.06 0.05

 Goose Lake 0.35 0.14

 Mud Lake 0.08 0.00

Pool 8

 Stoddard backwater – 0.33 b

 Pool 8 islands 0.36 0.37

 Shady Maple 0.43 0.50

 Lawrence Lake 0.34 0.66

 Goose Island 0.45 0.70

 Target Lake 0.05 0.16

Pool 13

 Johnson Creek 0.65 0.74

 Johnson Creek Levee 0.39 0.78

 Potter's Marsh 0.00 0.39

 Pomme de Terre 0.54 0.74

 Spring Lake 0.63 0.76

 Savanna Bay 0.50 0.65

 Brown's Lake 0.10 0.11
Location Spring sample diversity Summer sample diversity a a

C-2

Pool 26

 Calhoun Point 0.56 0.26

 Swan Lake 0.00 0.04

 Stump Lake 0.71 –

 Fuller Lake 0.78 –

La Grange Pool

 Grape Island 0.00 0.00

 Point Lake 0.18 0.10

 Spring Lake 0.50 0.29

 Bulrush Pond 0.30 0.68

Community diversity is calculated from a modification of Simpson's index (1949) calculated as 1 - 3(rf ) where rf is the relative a 2

frequency of each species.

The symbol “–” indicates no samples were taken during the sampling period at that location. b
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1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

June 1998

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

1992 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 , Heidi Langrehr , John Nelson , and Susan Romano-Peitzmeyer 1 2 3 4 4

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

Wisconsin Department of Natural Resources, Onalaska Field Station, 575 Lester Avenue, Onalaska, Wisconsin 54650; and 3

Illinois Natural History Survey, Havana Field Station, 704 N. Schrader Avenue, Havana, Illinois 62644 4

 REPORT NUMBER

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

U.S. Geological Survey 

Environmental Management Technical Center 98-P006

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 1992 effort of

monitoring submersed aquatic vegetation (SAV) along transects permanently established in vegetated locations within four navigation pools of the Upper Mississippi

River and one navigation pool of the Illinois River. More species of submersed aquatic macrophytes were found along transects in lower Pool 4 than in any other reach.

La Grange Pool and Pool 26 transects had the fewest species. Across all pools, sago pondweed (Potamogeton pectinatus) and coon's tail (Ceratophyllum demersum)

were the species most frequently found. Several species of SAV were seasonally dynamic at the transect locations, with changes in frequencies especially common among

sago and curly (P. crispus), and species of narrow-leaved pondweeds. Many of the species present in Pools 8 and 13 increased in frequencies between sampling periods,

resulting in a significantly higher proportion of sites with SAV by the summer sampling period. Although frequencies of individual species changed during the

growing season in Pools 4 and 26 and La Grange Pool, the proportion of sites with SAV remained stable. Community diversity within each pool was similar between

sampling periods except in Pool 13 where diversity increased at most locations during the season.

14. SUBJECT TERMS 15. NUMBER OF PAGES

1992 annual report, aquatic, Illinois River, LTRMP, Mississippi River, monitoring, plant, submersed, vegetation 24 pp. + Appendixes A–C

16. PRICE CODE

17. SECURITY CL ASSIFICATION 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.