Long Term Resource Monitoring Program

Program Report

98-P009

1994 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 
1994 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 Andrew Spink

Illinois Natural History Survey

Havana Field Station

704 N. Schrader Avenue

Havana, Illinois 62644

July 1998
Suggested citation:

Rogers, S., T. Blackburn, H. Langrehr, J. Nelson, and A. Spink. 1998. 1994 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-P009. 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 ........................................................................ vii

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

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

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

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

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

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

Statistical Analysis ............................................................ 10

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

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

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

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

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

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

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

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

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

Acknowledgments ............................................................... 21

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 1994 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 1994 ............ 11
iv

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

transect locations during the 1994 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

1994 spring and summer sampling periods ................................... 12

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

vegetation during the 1994 spring and summer sampling periods .................. 12

Table 7. Frequencies and relative frequencies (%) of species in Pool 4 during the 1994 spring and

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

Table 8. Locations in Pool 4 where species were present during the 1994 spring and summer

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

Table 9. Frequencies and relative frequencies (%) of species in Pool 8 during the 1994 spring and

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

Table 10. Locations in Pool 8 where species were present during the 1994 spring and summer

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

Table 11. Frequencies and relative frequencies (%) of species in Pool 13 during the 1994 spring and

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

Table 12. Locations in Pool 13 where species were present during the 1994 spring and summer

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

Table 13. Frequencies and relative frequencies (%) of species in Pool 26 during the 1994 spring and

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

Table 14. Frequencies and relative frequencies (%) of species in La Grange Pool, Illinois River,

during the 1994 spring and summer sampling periods ........................... 20

Table 15. Locations in La Grange Pool, Illinois River, where species were present during the 1994

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 1994 (Pools 4,

8, 13, 26 and La Grange Pool) .............................................. 3

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1994 monitoring of submersed

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

Figure 3. Pool 8, Upper Mississippi River, transect locations for the 1994 monitoring of submersed

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

Figure 4. Pool 13, Upper Mississippi River, transect locations for the 1994 monitoring of submersed

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

Figure 5. Pool 26, Upper Mississippi River, transect locations for the 1994 monitoring of submersed

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

Figure 6. La Grange Pool, Illinois River, transect locations for the 1994 monitoring of submersed

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

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 IllinoisRiver 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 (EMTC) during the 1994 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 1994, 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 1994. This report was

developed with funding provided by the Long Term Resource Monitoring Program.
1994 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 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 1994 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. A total of 17 species of SAV were found along

transects during the 1994 season. Several additional species were found during informal surveys. More species

of submersed aquatic macrophytes were found along transects in lower Pool 4 than in any other reach. Across

all pools, sago pondweed (Potamogeton pectinatus) was the species most frequently found. Several species of

SAV were seasonally dynamic at the transect locations, with changes in frequencies especially common among

sago pondweed and curly pondweeds (P. crispus). The proportion of sites with SAV decreased significantly in

Pool 4, increased in Pool 13, but did not change within other pools. Pool 26, however, was not sampled during

the summer sampling season because the transect locations were dewatered to promote growth of annual plant

species. Mean depths of sites with SAV ranged from 0.4 m in Pool 26 during spring sampling to 1.5 m in

La Grange Pool during spring and summer sampling.

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 and to help evaluate the trends. 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 1994. This report also provides an initial indication of features of submersed aquatic

vegetation (SAV) that can be compared with 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 improvement to 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, in part because few studies have adequately addressed the questions. Biologists, however, have high

interest and concern for this important component, 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;

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,
2

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 play a substantial role 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 1994 growing season was the fourth 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, gaining more significance with

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

River 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. 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. 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 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 1994 (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 1994, we monitored vegetation 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 11 backwater locations, of which 10 were monitored for the fourth year

(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, Upper Mud Lake (added in

1993), 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 (Appendix A). All locations except Upper Mud Lake are contiguous with the main channel

of the river.
4

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1994 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 1994 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
5

Figure 3. Pool 8, Upper Mississippi River,

transect locations for the 1994 monitoring of

submersed aquatic vegetation for the Long

Term Resource Monitoring Program.

Figure 4. Pool 13, Upper Mississippi River,

transect locations for the 1994 monitoring of

submersed aquatic vegetation for the Long Term

Resource Monitoring Program.

In Pool 8, we sampled SAV for the fourth year

at five locations including Target Lake, Lawrence

Lake, a backwater area near Goose Island, Shady

Maple, and the interior of Horseshoe Island (Figure

3). A small isolated backwater near Stoddard,

Wisconsin, added in 1992, and two locations added

in 1993 (Blue Lake and Pool 8 Islands) were also

monitored (Appendix A). 

In Pool 13, we sampled SAV at seven locations

(Figure 4). All locations were selected in 1991 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 1994 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program.

In Pool 26, we sampled SAV for the fourth year at three 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). Both Stump Lake and Calhoun Point areas

are managed by the Illinois Department of Natural Resources, which conducts water drainage with control

structures and pumping for waterf owl management. Fuller Lake, located at the northern end of Swan Lake,

was monitored for the third year.

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

Spring Lake, and Banner Marsh (Bulrush Pond; 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 and Spring Lake are

actively managed for fishing and are completely isolated. A fourth location added in 1992, a channel border

location by Grape Island, was also monitored.
7

Figure 6. La Grange Pool, Illinois River, transect locations for the 1994 monitoring of submersed aquatic

vegetation for the Long Term Resource Monitoring Program.

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. We did no

sampling in the areas between the groups.

Sampling was performed twice in most transect locations during the growing season to observe seasonal

changes in species composition and relative frequencies. We were not able to conduct sampling during the

summer period in Pool 26 because the transect locations were dewatered to promote annual vegetation growth

for waterfowl. 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 La Grange Pool, but were 30 m apart in Pool 4 because several of the
8

backwaters were too large to sample at the 15-m interval. 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 sampled 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.

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 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, bushy pondweed Najas flexilis (Willd.) Rostk. & Schmidt

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.
Table 2. Continued.

Family Common name Scientific name a,b a

9

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 Leafy pondweed Potamogeton foliosus Raf.

Potamogetonaceae Longleaf pondweed, Potamogeton nodosus Poir

river pondweedb

Potamogetonaceae Ribbonleaf pondweed Potamogeton epihydrus Raf.

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

Potamogetonaceae Sago pondweed Potamogeton pectinatus L.

Potamogetonaceae Small pondweed Potamogeton pusillus L.

Potamogetonaceae Variableleaf pondweed Potamogeton gramineus 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.

If a species was not collected during the 1991, 1992, or 1993 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 analyses with the vascular plants.

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 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. 
10

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.

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 vegetated with SAV are generally scarce.

Results

All Pools

During 1994, we found 17 species of submersed aquatic plants along transects across study pools. One of

the species found is a macroalgae, belonging to the muskgrass family (Characeae), which was included in the

analysis. We also found four species of floating-leaved plants (Appendix B), which were not included in the

analysis. The greatest number of submersed aquatic species found at transect sites during a sampling period

was 14 ( Pool 8 during spring sampling) and the fewest was one (Pool 26 during spring sampling). Sago

pondweed was the only species present in every study pool during both spring and summer sampling, and
11

tended to be present at frequencies generally above 10%, at least within the upper three pools. Coon's tail, curly

pondweed, and Eurasian watermilfoil were also prevalent species, found in four of the five pools. For some

unknown reason, Eurasian watermilfoil has not been found in Pool 26. Wild celery was most common in Pools

4 and 13, but 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 below 10% throughout all pools, especially in Pool 4 during

summer where no species reached a frequency above 8% (Table 3).

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 1994.a

Spring Summer

4 8 13 26 LG 4 8 13 26 LG

Species Fre Fre Fre Fre Fre Fre Fre Fre Fre Fre Fre 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 q q q q

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

Canadian waterweed 1.5 3.1 5.2 3.1 2.9 3.9 – – – – 1.4 5.1 13 9 4.9 4.6 – – – – 

b

Chara – – – – 0.1 0.1 – – 3.7 2.8 – – – – – – – – 5.1 4.4

Common bladderwort – – 0.5 0.2 – – – – – – – – 0.6 0.2 – – – – – – 

Coon's tail 2.6 5 35 30 6.1 7.6 – – 21 15 5.6 17 44 42 11 8.2 – – 22 19

Curly pondweed 14 40 28 26 6.9 6.1 – – 40 26 3.5 12 9.6 6.3 14 9.6 – – 6 2.6

Eurasian watermilfoil 0.9 2.6 22 20 5.4 7 – – 62 49 2.4 7.1 27 21 7.7 7.8 – – 63 64

Flatstem pondweed – – 4.9 2.9 0.3 0.2 – – – – – – 0.8 0.5 0.1 <0.1 – – – – 

Horned pondweed – – 0.1 <0.1 – – – – 0.5 0.3 0.1 0.2 – – – – – – 1.4 1.4

Longbeak buttercup – – 0.1 <0.1 – – – – – – – – – – – – – – – – 

Longleaf pondweed – – 0.2 0.1 0.2 0.1 – – 2.3 1.3 0.3 1 1 0.8 1.9 1.3 – – 3.2 2.9

Nodding waternymph – – 1.9 1.5 0.4 0.4 – – – – 0.3 1 4.3 3 2.5 2.3 – – 0.9 0.7

Sago pondweed 16 48 21 14 47 68 9 100 2.8 1.4 7.6 23 19 12 44 46 – – 2.3 1

Small and leafy pondweeds 0.3 0.5 1.9 1.7 – – – – 1.4 1.3 0.8 2.5 7.4 4.5 – – – – 1.4 0.5

Southern waternymph – – – – – – – – – – – – – – 1.3 1.6 – – – – 

Water stargrass 0.5 0.9 0.2 0.1 4.2 4.8 – – – – 0.5 1.3 0.5 0.2 14 12 – – – – 

Western waterweed – – – – – – – – 4.6 2.8 – – – – – – – – 6 4.3 c

Wild celery 0.3 0.5 0.2 0.1 1.3 1.5 – – – – 6.8 30 0.2 0.1 6.6 6.3 – – – – 

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

a

frequency columns to not total 100%.

The symbol "–" indicates the species was not found. b

Verification of specimen needed for positive identification. c

A few species dominated the relative frequencies within the pools. Sago pondweed ranked at least fourth,

and usually first or second, among relative frequencies in Pools 4, 8, and 13 during spring and summer

sampling and was the only species found in Pool 26. Curly pondweed also ranked high among the relative

frequencies in these pools, although frequencies tended to drop during the season. Coon's tail had the highest

relative frequency in Pool 8 during both spring and summer sampling and ranked a distant second or third in
12

Pools 4 and 13 and La Grange Pool. Eurasian watermilfoil reached the highest relative frequency across all

pools in La Grange Pool during spring and summer sampling. Wild celery reached the highest relative

frequency in Pool 4 during summer in spite of a low frequency (Table 3).

The proportion of sites vegetated with SAV to the total number of sampling sites decreased significantly

(based on Chi-square tests) in Pool 4, increased in Pool 13, but remained similar in Pool 8 and La Grange Pool

(Table 4). Decreases of SAV sites in Pool 4 were a result of declines in the frequencies of sago and curly

pondweeds between sampling periods. Increases in SAV sites in Pool 13 were a result of increases in

frequencies of several species. Pool 26 was not sampled during the summer sampling period. The proportion

of sites with submersed vegetation at our transect locations in La Grange Pool was relatively high compared

to other pools. The backwaters where transects are located are small and protected by levees from high

turbidity associated with 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. 

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

sites sampled at transect locations during the 1994 spring and summer

sampling periods.

Location Spring Summer 

Pool 4 32.5 20.4 (P < 0.01)a

Pool 8 62 62.2 (P > 0.90)

Pool 13 54.5 62.7 (P < 0.01)

Pool 26 8.9 not sampled

La Grange Pool 82.3 76.7 (P > 0.15)

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.

Water Depths and Substrates

Mean water depths at transect sites where submersed aquatic plants grew were from 0.4 m in Pool 26 during

spring sampling to 1.5 m in La Grange Pool (Table 5). La Grange Pool, where transects are located in

backwaters protected from high turbidity levels of the Illinois River main channel, was the only pool where

water depths reached more than 1 m.

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 1994 spring and summer sampling periods.

Location spring sampling deviation N summer sampling deviation N

Mean depth Standard Mean depth Standard

Pool 4 1 0.3 322 0.7 0.3 195

Pool 8 0.8 0.4 774 0.6 0.3 771

Pool 13 0.7 0.2 508 0.6 0.2 646

Pool 26 0.4 0.2 58 – – –

La Grange Pool 1.5 0.5 127 1.5 0.5 114
13

Generally, SAV was present on silt substrates for at least 55% of the total sampled throughout all pools.

All pools also reported between 5 and 28% ofsubstrate types as either silt with sand or mostly sand substrates

SAV (Table 6).

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

1994 spring and summer sampling periods.

Relative presence

Substrate type (n = 105) (n = 89) (n = 123) (n = 40) (n = 36)

Pool 4 Pool 8 Pool 13 Pool 26 La Grange Pool

Silt/clay 74.3 87.6 64.2 100 58.4

Mostly silt with sand 9.5 6.7 17.1 – 27.8 a

Mostly sand with silt/clay 16.2 5.6 18.7 – 13.8

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

Pool 4

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

during the summersampling period (Table 7). 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). Species with the highest

frequencies during the spring sampling periods were sago pondweed (16.4%) and curly pondweed (13.5%).

The frequency of curly pondweed declined to 3.5% between sampling periods; this decline was not unexpected

as the speciesis a “cool season strategist” and typically completes its annual cycle early in the growing season

(Nichols and Shaw 1986). The frequency of sago pondweed also declined to 7.6% (Table 7).

Table 7. Frequencies and relative frequencies (%) of species in Pool 4 during the 1994 spring and summer sampling

periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 1.5 1.4 3.1 5.1

Coon's tail 2.6 5.6 5 16.7

Curly pondweed 13.5 3.5 39.8 11.7

Eurasian watermilfoil 0.9 2.4 2.6 7.1

Horned pondweed – 0.1 – 0.2 b

Longleaf pondweed – 0.3 – 1

Nodding waternymph – 0.3 – 1

Sago pondweed 16.4 7.6 47.5 23.1

Small and leafy pondweeds 0.3 0.8 0.5 2.5

Water stargrass 0.5 0.5 0.9 1.3

Wild celery 0.3 6.8 0.5 30.2

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

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

The symbol “–” indicates the species was not found. b
14

Four additional species were found during informal surveys that were not found along transects. Species

found were all members of the pondweed family: Illinois pondweed, ribbonleaf pondweed, variableleaf

pondweed, and Richard's pondweed (Appendix B).

Most species, with the exception of sago pondweed and curly pondweed, were present at frequencies less

than 10% during the spring and summer sampling. Several species were found only during the summer

sampling period including horned pondweed, longleaf pondweed, and nodding waternymph. Although curly

pondweed and sago pondweed contributed to more than 85% of the relative frequencies during spring

sampling, by summer sampling, wild celery, sago pondweed, coon's tail, and curly pondweed shared the four

highest relative frequencies, contributing to more than 80% of the total relative frequencies (Table 7). 

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

decreased significantly (based on z-tests) at individual locations during the season, while wild celery increased

at four locations. Although sago pondweed was found distributed throughout all transect locations, significant

declines between spring and summer sampling occurred only at some of the upper pool locations (Table 8). 

Table 8. Locations in Pool 4 where species were present during the 1994 spring and summer sampling periods. 

Species sampling periods periods sampling periods

Decreased between No change between spring Increased between

spring and summer and summer sampling spring and summer

a b a

Canadian waterweed Big Lake

Big Lake Bay

Lower Peterson Lake 

Peterson Lake

Rice Lake

Robinson Lake 

Upper Mud Lake

Chara Big Lake

Coon's tail Big Lake Robinson Lake

Big Lake Bay

Dead Slough Lake

Lower Peterson Lake 

Peterson Lake

Rice Lake

Upper Mud Lake

Curly pondweed Lower Peterson Lake Bay City Flats 

Robinson Lake Big Lake

Big Lake Bay

Peterson Lake 

Rice Lake

Eurasian watermilfoil Big Lake

Big Lake Bay

Lower Peterson Lake 

Peterson Lake

Rice Lake

Robinson Lake
Table 8. Continued.

Species sampling periods periods sampling periods

Decreased between No change between spring Increased between

spring and summer and summer sampling spring and summer

a b a

15

Flatstem pondweed Big Lake

Mud Lake

Peterson Lake

Horned pondweed Robinson Lake

Longleaf pondweed Big Lake

Robinson Lake

Nitella Big Lake

Nodding waternymph Robinson Lake

Sago pondweed Bay City Flats Big Lake Robinson Lake

Dead Slough Lake Big Lake Bay

Upper Mud Lake Goose Lake

Lower Peterson Lake

Mud Lake

Peterson Lake

Rice Lake

Small and leafy pondweeds Peterson Lake

Rice Lake

Robinson Lake

Water stargrass Big Lake 

Big Lake Bay 

Lower Peterson Lake

Peterson Lake

Robinson Lake 

Wild celery Rice Lake Big Lake

Lower Peterson 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

Most species were distributed throughout transect locations in lower Pool 4, except for chara and nitella,

which were found only in the Big Lake area and horned pondweed, found only in Robinson Lake. Species found

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

pondweed (Table 8).
16

Pool 8

We found 14 species along Pool 8 transects during the spring sampling period and 12 species at the same

transect locations during the summer sampling period. Longbeak buttercup and horned pondweed were found

during spring sampling but not during summer sampling. Coon's tail, Eurasian watermilfoil, curly pondweed,

and sago pondweed all reached frequencies greater than 20% during the spring sampling period, contributing

to nearly 90% of the relative frequencies. The frequency of coon’s tail reached more than 40% during the

summer sampling period, and along with Eurasian watermilfoil and sago pondweed occupied over 75% of the

relative frequencies. Species that were sampled rarely (< 2% frequency) included common bladderwort, small

and leafy pondweeds (spring), nodding waternymph (spring), horned pondweed, water stargrass, flatstem

pondweed (summer), longleaf pondweed, and wild celery (Table 9). No additional species were found during

the informal surveys that were not found during the transect surveys.

Table 9. Frequencies and relative frequencies (%) of species in Pool 8 during the 1994 spring and summer sampling

periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 5.2 13.3 3.1 9.0

Common bladderwort 0.5 0.6 0.2 0.2

Coon's tail 35.0 44.2 29.5 41.5 

Curly pondweed 27.9 9.6 26.4 6.3

Eurasian watermilfoil 21.9 26.5 20.0 21.1 

Flatstem pondweed 4.9 0.8 2.9 0.5

Horned pondweed 0.1 – <0.1 –

b

Longbeak buttercup 0.1 – <0.1 –

Longleaf pondweed 0.2 1.0 0.1 0.8

Nodding waternymph 1.9 4.3 1.5 3.0

Sago pondweed 20.9 18.7 14.2 12.4 

Small and leafy pondweeds 1.9 7.4 1.7 4.5

Water stargrass 0.2 0.5 0.1 0.2

Wild celery 0.2 0.2 0.1 0.1

Frequencies and relative frequencies are based on all locations sampled during both sampling periods pooled together. Rounding may a

cause the relative frequencies columns to not total 100%.

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

Most species were distributed in at least two transect locations, except for longbeak buttercup found only

at Lawrence Lake, and horned pondweed found only at the Pool 8 Islands. Significant increases were noted

in at least one location for several species found during the spring sampling, especially in Target Lake.

Conversely, sago pondweed, curly pondweed, and flatstem pondweed revealed significant decreases at many

locations where they were present (Table 10). 
17

Table 10. Locations in Pool 8 where species were present during the 1994 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 Shady Maple Blue Lake

Lawrence Lake

Stoddard

Target Lake

Common bladderwort Blue Lake

Lawrence Lake 

Target Lake

Coon's tail Blue Lake Stoddard

Goose Island Target Lake

Horseshoe Island

Lawrence Lake

Pool 8 Island

Shady Maple

Curly pondweed Lawrence Lake Blue Lake Target Lake

Stoddard Goose Island

Horseshoe Island 

Pool 8 Islands

Shady Maple

Eurasian watermilfoil Goose Island Target Lake

Horseshoe Island

Lawrence Lake

Pool 8 Islands

Shady Maple

Flatstem pondweed Blue Lake Goose Island

Lawrence Lake Pool 8 Islands

Target Lake

Horned pondweed Pool 8 Islands

Longbeak buttercup Lawrence Lake

Longleaf pondweed Goose Island

Lawrence Lake

Target Lake

Nodding waternymph Goose Island Blue Lake

Horseshoe Island Target Lake

Lawrence Lake 

Sago pondweed Horseshoe Island Blue Lake Stoddard

Lawrence Lake Goose Island Target Lake

Pool 8 Islands Shady Maple

Small and leafy pondweeds Horseshoe Island Blue Lake

Lawrence Lake Goose Island

Stoddard Target Lake

Water stargrass Horseshoe Island

Lawrence Lake

Wild celery Lawrence Lake

Shady Maple

Target 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
18

Pool 13

We found 11 species along Pool 13 transects during the 1994 spring sampling period, and 10 species were

found during the summer sampling period (Appendix B). During both spring and summer sampling, sago

pondweed had at least 3 times the frequency of any other species, and thus dominated the relative frequencies.

Sago pondweed was the only species that reached a frequency above 10% during the spring sampling period,

declining only slightly between periods. By summer sampling, several species had increased in frequencies.

Those reaching above 10%, in addition to sago pondweed, were water stargrass, curly pondweed, and coon's

tail. These three species contributed to an additional 30% of the relative frequencies while sago pondweed

reached 45.8% of the relative frequencies. Species that were rarely found (<2% frequency) during at least

one sampling period included chara, flatstem pondweed, longleaf pondweed, nodding waternymph (spring), and

wild celery (spring; Table 11). 

Table 11. Frequencies and relative frequencies (%) of species in Pool 13 during the 1994 spring and summer sampling

periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 2.9 4.9 3.9 4.6

Chara 0.1 – 0.1 –

b

Coon's tail 6.1 10.7 7.6 8.2

Curly pondweed 6.9 14.4 6.1 9.6

Eurasian watermilfoil 5.4 7.7 7 7.8

Flatstem pondweed 0.3 0.1 0.2 <0.1 

Longleaf pondweed 0.2 1.9 0.1 1.3

Nodding waternymph 0.4 2.5 0.4 2.3

Sago pondweed 47.1 43.5 68.2 45.8 

Southern waternymph – 1.3 – 1.6

Water stargrass 4.2 13.5 4.8 12.2 

Wild celery 1.3 1.5 6.3

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

columns to not total 100%.

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

Most species were distributed throughout two or more locations, except for chara and flatstem pondweed

found only at the Johnson Creek area. Many species showed significant increases in frequencies in at least one

location in Pool 13 during the 1994 growing season. The only species that significantly declined was sago

pondweed at Potter's Marsh and the Johnson Creek area (Table 12).
19

Table 12. Locations in Pool 13 where species were present during the 1994 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 Johnson Creek 

Johnson Creek Levee 

Pomme de Terre

Chara Johnson Creek 

Johnson Creek Levee

Coon's tail Johnson Creek Brown’s Lake

Johnson Creek Levee Spring Lake

Pomme de Terre 

Savanna Bay

Curly pondweed Johnson Creek Brown's Lake

Johnson Creek Levee 

Potter's Marsh

Savanna Bay

Spring Lake

Eurasian watermilfoil Johnson Creek

Johnson Creek Levee

Pomme de Terre

Potter's Marsh

Spring Lake

Flatstem pondweed Johnson Creek

Johnson Creek Levee

Longleaf pondweed Brown's Lake

Johnson Creek

Johnson Creek Levee

Pomme de Terre

Savanna Bay

Spring Lake

Nodding waternymph Spring Lake Johnson Creek

Johnson Creek Levee 

Sago pondweed Johnson Creek Pomme de Terre Brown’s Lake

Johnson Creek Levee Savanna Bay 

Potter's Marsh Spring Lake

Water stargrass Pomme de Terre Johnson Creek

Savanna Bay Johnson Creek Levee

Spring Lake Potter's Marsh

Wild celery Pomme de Terre Johnson Creek

Potter's Marsh Johnson Creek Levee

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
20

Pool 26

We found only one species of SAV during the spring sampling period in Pool 26 (Table 13). We were not

able to conduct sampling during the summer sampling period because the transect locations were dewatered

by the summer sampling period to promote annual vegetation growth for waterfowl.

Table 13. Frequencies and relative frequencies (%) of species in Pool 26 during the 1994 spring and summer sampling

periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Sago pondweed 9 – 100 –

b

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

La Grange Pool

We found a total of 10 species of SAV at transect locations in the La Grange Pool during the 1994 period

(Table 14). Species frequencies in La Grange Pool were dominated by Eurasian watermilfoil, curly pondweed

and coon's tail during the spring sampling period. These three species contributed to 90% of the relative

frequencies during the spring sampling. During the summer sampling period, coon’s tail and Eurasian

watermilfoil shared more than 80% of the relative frequencies whereas curly pondweed dropped to less than

3% relative frequency. All other species were present at frequencies below 10% during both sample periods.

La Grange Pool backwaters are the only locations within our study areas where we found western waterweed.

Table 14. Frequencies and relative frequencies (%) of species in La Grange Pool, Illinois River, during the 1994 spring

and summer sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Chara 3.7 5.1 2.8 4.4

Coon's tail 20.9 22.3 15 18.5

Curly pondweed 40 6 26.1 2.6

Eurasian watermilfoil 62.3 63.2 48.8 63.7

Horned pondweed 0.5 1.4 0.3 1.4

Longleaf pondweed 2.3 3.2 1.3 2.9

Nodding waternymph 0.4 0.9 0.4 0.7

Sago pondweed 2.8 2.3 1.4 1

Small and leafy pondweeds 1.4 1.4 1.3 0.5

Western waterweed 4.6 6 2.8 4.3

Frequencies and relative frequencies are based on all transect locations pooled together. Rounding may cause the relative frequencies a

columns to not total 100%.
21

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

one exception was curly pondweed which declined in Spring Lake (Table 15).

Table 15. Locations in La Grange Pool, Illinois River, where species were present during the 1994 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 Banner Marsh

Point Lake

Spring Lake

Curly pondweed Spring Lake Banner Marsh

Eurasian watermilfoil Banner Marsh

Spring Lake

Horned pondweed Banner Marsh

Longleaf pondweed Banner Marsh

Sago pondweed Grape Island

Point Lake

Spring Lake

Small and leafy pondweeds Banner Marsh

Point Lake

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

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.
22

References

Barko, J. W., D. Gunnison, and S. R. Carpenter. 1991. Sediment interactions with submersed macrophyte

growth and community dynamics. Aquatic Botany 41:41–65.

Engel, S. 1990. Ecosystem responses to growth and control of submerged macrophytes: A literature review.

Technical Bulletin 170. Wisconsin Department of Natural Resources, Madison. 20 pp.

Fassett, N. C. 1966. A manual of aquatic plants. University of Wisconsin Press, Madison. 405 pp.

Gleason, H. A., and A. Cronquist. 1991. A manual of vascular plants of northeastern United States and

adjacent Canada. 2nd edition. The New York Botanical Garden, Bronx. 910 pp.

Gutreuter, S., R. W. Burkhardt, M. Stopyro, A. Bartels, E. Kramer, M. C. Bowler, F. A. Cronin, D. W.

Soergel, M. D. Petersen, D. P. Herzog, P. T. Raibley, K. S. Irons, and T. M. O’Hara. 1997. 1994 annual

status report: A summary of fish data in six reaches of the Upper Mississippi River System. U.S.

Geological Survey, Environmental Management Technical Center, Onalaska, Wisconsin, July 1997.

LTRMP 97-P007. 15 pp. + Chapters 1–6.

Jessen, R., and R. Lound. 1962. An evaluation of survey techniques for submerged aquatic plants. Game

Investigational Report 6. Minnesota Department of Conservation, St. Paul. 10 pp.

Korschgen, C. E., L. S. George, and W. L. Green. 1988. Feeding ecology of canvasbacks staging on Pool 7

of the Upper Mississippi River. Pages 237–249 in M. W. Weller, editor. Waterfowl in winter. University

Minnesota Press, Minneapolis.

Laustrup, M. S., and C. D. Lowenberg. 1994. Development of a systemic land cover/land use database for the

Upper Mississippi River System derived from Landsat Thematic Mapper satellite data. National Biological

Survey, Environmental Management Technical Center, Onalaska, Wisconsin, May 1994. LTRMP 94-T001.

103 pp.

Nichols, S. A., and B. H. Shaw. 1986. Ecological life histories of three aquatic nuisance plants, 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 1994 Sampling Season

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

Number of of sites of sites sampled sampled between 

Number Number Dates Dates Distance 

Pool 4

Bay City Flats 3 78 62 6/6 8/5 30

(Catherine Pass;a

M787.0)b

Big Lake 5 156 149 5/24, 7/28; 30

(M757.5) 26–27 8/1

Big Lake 3 29 23 5/20 7/27 30

(M758.0)

Big Lake Bay 3 52 30 5/20 7/27 30

(M758.5)

Dead Slough Lake 9 139 136 6/3, 6 8/4–5 30

(M789.2, M788.5, M788.0)

Goose Lake 3 26 27 6/6 8/5 30

(M788.G)c

Lower Peterson Lake 4 115 132 5/17 7/19–20 30

(M753.5)

Mud Lake 3 59 53 6/1 8/4 30

(M791.3)

Peterson Lake 6 69 72 5/16 7/19 30

(M754.8, M754.5)

Robinson Lake 9 223 221 5/18–19 7/21–22, 25–26 30

(M758.R)

Upper Mud Lake 4 44 46 6/13 8/3–4 30

(M791.5)

 Total Pool 4 52 990 951 15 15

Pool 8

Blue Lake 3 112 110 5/31 7/29; 8/2 15

(M697.0)

Goose Island 5 112 112 6/2 8/4 15

(M692.0)

Horseshoe HREP 5 76 78 6/1 8/11 15 d

(M687.0)

Lawrence Lake 6 (spring) 392 407 6/6, 8–9, 13, 8/12, 15–16, 15

(M691.0) 10 (summer) 16–17, 20 18, 22–25

Pool 8 Islands 3 107 102 5/23–24 8/28 15

(M686.0)

Shady Maple 3 100 105 6/3 8/29 15

(M690.0)

Stoddard 4 48 47 5/27 7/28 15

(M684.0)
Location transects in spring in summer in spring in summer sites (m) 

Number of of sites of sites sampled sampled between 

Number Number Dates Dates Distance 

A-2

Target Lake 11 298 278 5/16–19 7/20–22, 15

(M696.0) 25–26

 Total Pool 8 44 1,245 1,239 11 18

Pool 13

Brown's Lake 25 379 390 6/1–3, 7 8/1–5, 8 15

(M545.1, M544.5)

Johnson Creek Levee 4 83 89 6/9 8/17 15

(M523.5)

Lower Johnson Creek 2 41 59 5/20 7/26–27 15

(M523.0)

Pomme de Terre 5 74 82 5/19 8/15 15

(M526.0)

Potter's Marsh 6 77 101 6/8 8/16 15

(M524.0)

Savanna Bay 12 151 134 5/20, 25 7/28–29 15

(M541.5, M540.5, M539.5)

Spring Lake 12 136 176 5/25, 27, 31 8/9, 11 15

(M534.8, M533.6, M532.0)

 Total Pool 13 66 941 1,031 16 12

Pool 26

Calhoun Point 17 155 not sampled 6/1 not sampled 15

(I003.0)e,f

Fuller Lake 2 45 not sampled 6/12

(I011.5)

Stump Lake 8 169 not sampled 157 not sampled 15

(I010.0)

Swan Lake 11 276 not sampled 5/24–25 not sampled 15

(I005.5)

 Total Pool 26 38 645 0 7 6

La Grange Pool

Bulrush Pond 2 26 22 5/25–26 8/1 15

(I140.7)a

Grape Island 3 18 21 5/24 7/29 15

(I086.4)

Point Lake 6 25 26 6/14 9/2 15

(I100.0)

Spring Lake 5 146 146 5/18–20, 23 8/4, 12, 16 15

(I135.5)

 Total La Grange Pool 16 215 215 9 8

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 f

River, 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 Present at Transect

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

the La Grange Pool (Illinois River) 

Species Pool 4 Pool 8 Pool 13 Pool 26 Pool

La Grange 

Submersed Aquatic Species

Canadian waterweed

(Elodea canadensis L.) x x x – –

a b

Chara – – x – x

(Chara spp.)

Common bladderwort

(Utricularia macrorhiza L.) – x – – –

Coon's tail

(Ceratophyllum demersum L.) x x x – x

Curly pondweed

(Potamogeton crispus L.) x x x – x

Eurasian watermilfoil

(Myriophyllum spicatum L.) x x x – x

Flatstem pondweed

(Potamogeton zosteriformis Fern.) x x – –

–

Horned pondweed

(Zannichellia palustris L.) x x – – x

Longbeak buttercup – x – – –

(Ranunculus longirostris Godron.)

Longleaf pondweed

(Potamogeton nodosus Poiret.) x x x – x

Nodding waternymph

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

Schmidt) 

Sago pondweed

(Potamogeton pectinatus L.) x x x x x

Small and leafy pondweeds

(Potamogeton pusillus and x x – – x

P. foliosus L.)

Water stargrass

(Heteranthera dubia L.) x x x – –

Western waterweed – – – – x

(Elodea nuttallii [Planch.] St. John)

Wild celery, American eelgrass

(Vallisneria americana Michx.) x x x – –
Species Pool 4 Pool 8 Pool 13 Pool 26 Pool

La Grange 

B-2

Floating-leaved Species

American lotus x x x – x

(Nelumbo lutea [Willd.] Pers.)

American white waterlily x x – – x

(Nymphaea tuberosa Ait.)

Yellow pondlily x x – – –

(Nuphar lutea [L.] Sm.)

 Total per pool 

 Submersed aquatic species 11 14 11 10 10

 Floating-leaved species 3 3 1 2

Additional Species Found During Informal Surveys

Illinois pondweed x – – – –

(Potamogeton illinoisensis Morong.)

Longbeak buttercup x – – – –

(Ranunculus longirostris Godron.)

Ribbonleaf pondweed x – – – –

(Potamogeton epihydrus Raf.)

Richard’s pondweed x – – – –

(Potamogeton richardsonii [Benn.]

Rydb.)

Variable leaf pondweed x – – – –

(Potamogeton gramineus L.)

 Total number of submersed 19 1

 aquatic vegetation and

 floating-leaved speciesc

The symbol "x" indicates the species was present during at least one sampling period. a

The symbol "–" indicates the species was not found. b

Total per pool is the total number of species present regardless of sampling period, including informal sampling. c
REPORT DOCUMENTATION PAGE Form Approved

OMB No. 0704-0188

Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing

data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or

any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information

Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction

Project (0704-0188), Washington, D.C. 20503

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

July 1998

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

1994 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 Andrew Spink 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. 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-P009

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 

(1-800-553-6847 or 703-487-4650)

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 1994 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. A total of 17 species of SAV were found along transects during the 1994 season. Several additional species were

found during informal surveys. More species of submersed aquatic macrophytes were found along transects in lower Pool 4 than in any other reach. Across all pools,

sago pondweed (Potamogeton pectinatus) was the species most frequently found. Several species of SAV were seasonally dynamic at the transect locations, with

changes in frequencies especially common among sago pondweed and curly pondweeds (P. crispus). The proportion of sites with SAV decreased significantly in Pool 4,

increased in Pool 13, but did not change within other pools. Pool 26, however, was not sampled during the summer sampling season because the transect locations were

dewatered to promote growth of annual plant species. Mean depths of sites with SAV ranged from 0.4 m in Pool 26 during spring sampling to 1.5 m in La Grange Pool

during spring and summer sampling.

14. SUBJECT TERMS 15. NUMBER OF PAGES

1994 annual status report, aquatic, Illinois River, LTRMP, Mississippi River, monitoring, plant, submersed, vegetation 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.