Long Term Resource Monitoring Program

Program Report

98-P005

1991 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 
1991 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

Daniel Dieterman

Minnesota Department of Natural Resources

1801 S. Oak Street

Lake City, Minnesota 55041 

Heidi Langrehr

Wisconsin Department of Natural Resources

Onalaska Field Station

575 Lester Avenue

Onalaska, Wisconsin 54650

John Nelson and 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, D. Dieterman, H. Langrehr, J. Nelson, and S. Romano-Peitzmeyer. 1998. 1991 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-P005. 21 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

Preface ........................................................................ vii

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

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

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

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

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

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

Sediments ................................................................. 9

Nutrients ................................................................. 9

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

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

Results ........................................................................ 11

All Pools .................................................................... 11

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

Pool 8 ...................................................................... 14

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

Pool 26 ..................................................................... 18

La Grange Pool ............................................................... 19

Acknowledgments ............................................................... 20

References ..................................................................... 21

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 aquatic vegetation in 1991 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. 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 1991 spring and summer

sampling periods ....................................................... 11
iv

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

transect locations during the 1991 spring and summer sampling periods ............. 12

Table 5. Means and standard errors for percent moisture, bulk density, and percent organic matter

collected in 1991 at randomly selected sites along transects in Pools 4, 8, 13, and 26 of the

Upper Mississippi River and La Grange Pool of the Illinois River ................. 13

Table 6. Frequencies and relative frequencies (%) of species found in Pool 4 during 1991 spring and

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

Table 7. Pool 4 transect locations where species were present in the 1991 showing increase or

decrease in species between spring and summer sampling periods ................. 15

Table 8. Frequencies and relative frequencies (%) of species at transect locations in Pool 8 during

the 1991 spring and summer sampling periods ................................ 16

Table 9. Pool 8 transect locations where species were present in 1991 showing increase or decrease

in species between spring and summer sampling periods ........................ 17

Table 10. Frequencies and relative frequencies (%) of species in Pool 13 during the 1991 spring and

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

Table 11. Pool 13 transect locations where species were present in the 1991 showing increase or

decrease in species between spring and summer sampling periods ................. 18

Table 12. Frequencies and relative frequencies (%) of species in Pool 26 during the 1991 spring and

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

Table 13. Pool 26 transect locations where species were present in the 1991 showing increase or

decrease in species between spring and summer sampling periods ................. 19

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

during 1991 spring and summer sampling periods .............................. 20

Table 15. La Grange Pool, Illinois River, transect locations where species were present in 1991

showing increase or decrease in species between spring and summer sampling periods . 20

Figures

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

Resource Monitoring Program submersed vegetation surveys of 1991 (Pools 4, 8, 13, 26,

and La Grange Pool) ..................................................... 3

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1991 monitoring of submersed

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

Figure 3. Pool 8, Upper Mississippi River, transect locations for the 1991 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 1991 monitoring of submersed

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

Figure 5. Pool 26, Upper Mississippi River, transect locations for the 1991 monitoring of submersed

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

Figure 6. La Grange Pool, Illinois River, transect locations for the 1991 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 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

1991 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 1991, 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 presence and distribution of

submersed aquatic vegetation collected from the field stations for 1991. This report was

developed with funding provided by the Long Term Resource Monitoring Program. 
1991 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, Daniel Dieterman, Heidi Langrehr,

John Nelson, and Susan Romano-Peitzmeier

Abstract

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

Monitoring Program. This report summarizes the 1991 effort of monitoring submersed aquatic vegetation (SAV)

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

River and one navigation pool of the Illinois River. Seventeen species of submersed aquatic plants were found

along transects in Pools 4, 8, 13, 26, and La Grange Pool. The highest number of submersed aquatic plant species

found in any one pool was 16 in Pool 4 and the lowest number was 6 in La Grange Pool. Coon’s tail

(Ceratophyllum demersum) and sago pondweed (Potamogeton pectinatus) were the only two species found in

every study pool during both spring and summer sampling. Decreases in pondweed species noticeably affected

the number of transect sites with SAV in Pools 4 and 13. In Pool 8, nearly all species declined between sampling

periods and the proportion of sites with SAV dropped to less than 10% by August, the most decline of any pool.

Introduction

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

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

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

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

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

management. The purpose of this report is to document sampling along transects at selected locations in 1991.

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 in 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; 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 have a substantialrole in increasing our understanding of trends in this resource

by addressing the following questions:

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

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

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

The 1991 growing season was the first 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 in selected locations of the UMRS,

(2) compare present and future distribution of SAV, and

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

distribution of SAV.

This report partially fulfills the first objective. Fulfillment of the second objective will 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 the environment on

abundance and distribution requires focused initiatives to explore plant response to key factors, singly or in

combination with one another.

Study Areas

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

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

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

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

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

for the Mississippi 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 located in an

upper impounded reach characterized by high percentages of open water and aquatic vegetation and low

agricultural use. 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). Qualitatively, Pools 4, 8, and 13 are geomorphically complex and richly braided by side channels

and backwaters. 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. The main channel and main

channel border habitats make up the greater proportion of the water surface (Table 1) and habitats suitable for

aquatic vegetation make up a very small proportion of the total area (Peck and Smart 1986). 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 in the Long Term

Resource Monitoring Program submersed vegetation surveys of 1991 (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.

To locate vegetated areas to monitor, we conducted field reconnaissance and used historical reports,

conversations with biologists familiar with the river, and 1989 aerial photographs and land cover vegetation

maps. Depending on the size of the backwater and the extent of the vegetation, transects either traversed all

or a portion of the backwater or, if bordering a channel or large expanse of open water, extended to the edge

of a vegetated bed.

In Pool 4, we selected 10 contiguous backwater lakes for placement of permanent transects (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, Lower Peterson

Lake, Rice Lake, and Big Lake Bay.
4

Figure 2. Pool 4, Upper Mississippi River, transect locations for the 1991 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 aquatic vegetation in 1991 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 1991 monitoring of submersed

aquatic vegetation for the Long Term Resource

Monitoring Program.

Figure 4. Pool 13, Upper Mississippi River, transect

locations for the 1991 monitoring of submersed

aquatic vegetation for the Long Term Resource

Monitoring Program.

In Pool 8, we selected five locations for placement of permanent transects including Target Lake,

Lawrence Lake, Shady Maple, the interior of Horseshoe Island, and a backwater area near Goose Island,

(Figure 3). These locations were primarily in the lower two thirds of the pool.

In Pool 13, we selected seven locations with SAV for placement of permanent transects (Figure 4). The

transect locations were distributed primarily in the middle and lower portions of the pool and included

backwater habitats and impounded areas. Locations chosen were Brown's Lake, Savanna Bay, Spring Lake,

Pomme de Terre, Potter's Marsh, Lower Johnson Creek, and Johnson Creek Levee (Appendix A).
6

Figure 5. Pool 26, Upper Mississippi River, transect locations for the 1991 monitoring of submersed

aquatic vegetation for the Long Term Resource Monitoring Program.

In Pool 26, we selected three vegetated backwater sites for placement of permanent transects (Figure 5).

Transect locations were distributed in the Calhoun Point area, which consists of several backwater lakes,

sloughs, and wet-weather (temporary) ponds, and in Swan Lake and Stump Lake (Appendix A). The selected

areas are actually managed backwaters of the lower Illinois River. Using control structures and pumping, the

Illinois Department of Natural Resources seasonally drains these areas for waterfowl management.

In La Grange Pool, we selected three backwaters for transect locationsincluding Point Lake, Spring Lake,

and Banner Marsh (Figure 6). The three are among the few locations where submersed vegetation are still

found in this river reach. These backwaters are classified as isolated and are protected from the main stem

of the Illinois River by agricultural levees. Point Lake, however, 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.

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. Peterson Lake (Pool 4), for example, has three transects in

the upper portion, three in the middle portion, and four in the lower portion. No sampling was performed in

the areas between the groups.
7

Figure 6. La Grange Pool, Illinois River, transect locations for the 1991 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. Several transect locations were not chosen until the

summer sampling period, thus, sampling was performed only once at those locations. Locations sampled only

during the summer included Horseshoe Island and the Goose Island backwater (Pool 8), Savanna Bay and

Spring Lake (Pool 13), and Banner Marsh (La Grange Pool). Sampling was done at only every other site in

Swan Lake (Pool 26) during the summer sampling period after preliminary survey work revealed that the

vegetated area had been uprooted. Also, Stump Lake (Pool 26) was drained in the summer and sampling could

not be conducted there. We began sampling late in the spring sampling window (which was to run from

May 15 through June 15) because time was taken at the beginning of the season to select locations and mark

transect starting points. Sampling, therefore, began in late May or early June and continued into the first week

of July. 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 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
8

rake to the bottom and twisting it to snag plants—instead of dragging it as did Jessen and Lound. (In Pool 4,

the rake was dragged over a distance extending up to 0.6 m along the sediment surface.) 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

2

were identified and recorded. After all three casts were made, each species recovered was assigned a rating

of 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% visible vegetative cover within the sample area, 26–50%, 51–75%, and 76–100%). Floating-leaved

species are listed in the taxa list (Appendix B) but were not used in analysis of data because our focus was on

submersed species.

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.

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 , shortspike Myriophyllum sibiricum Komarov b

watermilfoil

Haloragaceae Eurasian watermilfoil , Myriophyllum spicatum L. b

spike watermilfoil

Hydrocharitaceae Canadian waterweed Elodea canadensis

Hydrocharitaceae Western waterweed Elodea nuttallii Planch.

Hydrocharitaceae Wild celery , Vallisneria americana Michx. b

American eelgrass

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, Potamogeton crispus L.

curlyleaf pondweed

Potamogetonaceae Flatstem pondweed Potamogeton zosteriformis Fern.

Potamogetonaceae Illinois pondweed Potamogeton illinoisensis Morong.

Potamogetonaceae River pondweed , Potamogeton nodosus Poir b

longleaf pondweed

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 on the Internet.

At least one sample of each species found 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 sampling in the field and were combined

during analysis. Two species of macroalgae, chara (Chara spp.) and nitella (Nitella spp.), were included in the

analysis with the vascular plants.

Environmental Factors

Sediments

To acquire information on the relation between macrophyte presence and sediment composition, sediments

at transect sites were cataloged subjectively into five broad categories (muck-organic, silt-clay, sand-silt, sand,

and sand-clay) based on visual and tactile characteristics. About 10% of the sites along transects were

randomly selected for collecting sediment cores. The cores were collected with a Wildco sediment corer with

a 5-cm ID acrylic core liner (Wildlife Supply Company, Saginaw, Michigan) to a depth of approximately 10

cm. Cores were frozen for later analysis. Measured volumes of the sediment were dried at 105 °C for about

12 h to determine sediment moisture content and bulk density. Dried samples were combusted in a muffle

furnace at 550 °C for estimations of organic matter content from loss of mass following ignition (Allen et al.

1974).
10

Nutrients

Aboveground plant tissues of several common species of SAV were collected from a few randomly selected

transect sites to determine nitrogen and phosphorus content. Tissue concentrations have been considered

reliable indicators of the availability of an element in the environment (Gerloff and Krombholz 1966). Forty

samples from all pools, except Pool 4, were collected and analyzed. Dried above-ground plant tissue samples

were ground (<0.7 mm diameter) in a Wiley Mill and digested with sulfuric acid and hydrogen peroxide (Allen

et al. 1974). Both N and P concentrations were determined colorimetrically with a Technicon Autoanalyzer

II (Bran + Luebbe Analyzing Technology Inc., Elmsford, New York).

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 casts for species i, and Ef = number of rake grabs for all i i i

species. Species of floating-leaved vegetation were omitted from the calculations because the life form is better

documented using a geographic information system. 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:

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

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

Species richness is defined as the number of different species found through rake grabs. This provides an

observed count for each pool but does not mean these are all the species present within a pool or even within

a transect location. Determination of species richness in an exact sense is not possible (Greig-Smith 1983)

because species richness is a function of sample size. The focusin this report, therefore, is a simple qualitative

assessment of trends in observed species numbers.

Informal Surveys

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

we began to establish protocols for conducting surveys throughout each pool. Aerial photographs and

bathymetry maps were used to locate sites supporting or likely to support SAV. Surveys were conducted by

boating along channel border habitats and through other areas most likely to support vegetation but not covered

by sampling along transects. If vegetated areas or patches of vegetation were seen at or near the surface,

samples were gathered using a rake. An estimate of abundance (rare, common, abundant) was given to each
11

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

areas and patches were recorded.

Informal surveys during 1991 did not cover as many areas as we would have preferred in a given pool

because of time constraints. Selection of and sampling along transect locations left less time than needed for

informal surveys before the second sampling period was scheduled to begin.

Results

All Pools

We found 15 species of submersed vascular aquatic plants and two species of macroalgae of the muskgrass

family (Characeae) along transects in Pools 4, 8, 13, and 26 and La Grange Pool in 1991. We also found four

species of floating-leaved plants and have included them in our species list (Appendix B). Across the study

pools, the greatest number of submersed aquatic speciesfound at transect sites in a single pool was 16 (Pool 4

in spring), and the fewest was 5 (La Grange Pool in spring and Pool 26 in summer). Only one additional

species, northern watermilfoil, was found during informal surveys (in Pool 4) that was not found along the

transects.

Coon’s tail and sago pondweed were the only two species found in every study pool during both spring and

summer sampling. Relative frequencies of coon’s tail increased in all pools except Pool 8 between spring and

summer and relative frequencies of sago pondweed declined in all pools except La Grange Pool between the

two sampling periods (Table 3). Spring relative frequencies for coon’s tail were from 7.0% in La Grange Pool

to 65.6% in Pool 8 and summer relative frequencies were from 14.6% in Pool 13 to 83.9% in Pool 26. Spring

relative frequencies for sago pondweed were from 0.3% in La Grange Pool to 73.1% in Pool 13. Summer

relative frequencies for sago pondweed were from 0.7% in La Grange Pool to 60.3% in Pool 13. Eurasian

watermilfoil was present in all pools except Pool 26, reaching highest relative frequencies during spring in

La Grange Pool (82.7%) and during summer in Pool 8 (62.1%) and La Grange Pool (68.9%). In all other pools,

the relative frequency of Eurasian watermilfoil remained less than 10.0% (Table 2). 

Relative frequencies of most other species remained lessthan 5.0%. Species reaching relative frequencies

greater than 5.0% during at least one sampling period were Canadian waterweed (Pool 4), chara (La Grange

Pool), curly pondweed (Pools 4 and 8), longleaf pondweed (Pools 8 and 26), small and leafy pondweeds

(Pool 4), water stargrass (Pool 4), and wild celery (Pools 4 and 13; Table 3).

Horned pondweed, nitella, and Richardson’s pondweed were found rarely in Pool 4, but were not found in

other pools. Chara was found in Pool 4 and in La Grange Pool in spring and summer. Western waterweed was

found only in La Grange Pool (positive identification still pending verification by an outside source).

Table 3. 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 1991 spring and summer sampling periods.a

Spring Summer

Species 4 8 13 26 LG 4 8 13 26 LG

Canadian waterweed 8.9 1.6 – 0.3 – 10.4 – – – –

b

Chara 0.2 – – – 9.6 p – – – 8.6 c

Common bladderwort 0.1 0.1 – – – – – – – –

Coon's tail 19.3 65.6 9.1 30.9 7.0 23.6 12.5 14.6 83.9 23.5
Table 3. Continued.

Spring Summer

Species 4 8 13 26 LG 4 8 13 26 LG

12

Curly pondweed 7.0 2.8 1.6 0.4 – 0.6 37.5 0.9 1.6 –

Eurasian watermilfoil 2.6 0.5 6.9 – 80.7 5.5 18.7 9.1 – 66.7

Flatstem pondweed 3.4 4.6 0.2 – – 4.3 – – – –

d

Horned pondweed 0.2 – – – – p – – – –

Longleaf pondweed 0.7 – 2.6 8.1 – 1.5 – 4.1 0.4 –

Nitella 0.1 – – – – 0.2 – – – –

Nodding waternymph 0.9 – – – – 1.2 – 0.5 – –

Richardson’s pondweed p – – – – p – – – –

Sago pondweed 15.4 24.3 73.1 55.4 0.3 6.7 31.2 60.3 13.8 0.3

Small and leafy pondweeds 16.6 – 0.2 4.8 – 4.2 – – 0.4 –

Water stargrass 7.3 – ? – – 12.9 – – – –

d

Western waterweed – – – – 0.3 – – – – 0.9 e

Wild celery 17.2 0.4 6.3 – – 28.8 – 10.5 – –

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

100%.

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

p=Relative frequency less than 0.1. c

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

Verification of specimen needed for positive identification. e

The proportion of sites with SAV to the total number of sampling sites declined significantly between

spring and summer sampling periods (based on Chi-square tests) in Pools 4, 8, and 13, but not in Pool 26 or

La Grange Pool. Species of pondweeds that declined between sampling periods were the primary contributors

to changes in the proportion of SAV sites. Our spring sampling period was conducted later than planned

(mostly in mid- to late-June), thus, we may have sampled at the time of peak growth of sago pondweed, curly

pondweed, and small and leafy pondweeds. In Pool 8, however, loss of several other species, especially in

Lawrence Lake, also contributed to the change within the pool. In Pool 26, loss of sago pondweed was

balanced by an increase in coon’s tail, thus the proportion of SAV sites remained relatively unchanged. In La

Grange Pool, pondweeds made up a very small portion of the total number of SAV and fluctuations in other

species were not great enough to cause a significant change (Table 4).

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

sites sampled at transect locations during the 1991 spring and summer

sampling periods.

Location Spring Summer

Pool 4 67.8 54.0 (0.001)a

Pool 8 75.0 6.8 (0.001)

Pool 13 38.7 28.2 (0.001)

Pool 26 46.2 48.5 (0.542)

La Grange Pool 88.6 84.0 (0.326)

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

a

P-values are based on Chi-square tests with a 0.05 level of significance.
13

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

high compared to other pools. This was probably because these backwaters were small and sheltered from wind

turbulence and high turbidity associated with the main channel of the Illinois River. Thus, SAV tends to cover

the surfaces of these backwaters.

Submersed aquatic species were present mostly on sandy silts throughout all pools. Laboratory analysis of

sediment cores taken at 10% of the transect sites revealed mean bulk densities were from 0.91 g/mL in Pool 13

to 0.53 g/mL in Pool 8 (n = 156, standard error [SE] = 0.02). Bulk density, which closely parallels sand

content, suggests that sediments at transect sites contained relatively high sand fractions. Mean percent

moisture content were from 39.01 in Pool 13 to 58.31 in Pool 8. Percent organic matter were from 6.36 in

Pool 13 to 10.91 in Pool 8 (Table 5).

Table 5. Means and standard errors for percent moisture, bulk density, and percent organic matter collected

in 1991 at randomly selected sites along transects in Pools 4, 8, 13, and 26 of the Upper Mississippi River and

La Grange Pool of the Illinois River.

Pool and n moisture error bulk density error organic error a

Mean % Standard Mean % Standard Mean % Standard

Pool 4 43.84 1.08 0.80 0.02 8.19 0.64

n = 165

Pool 8 58.31 1.04 0.53 0.01 10.91 0.42

n = 156

Pool 13 39.01 0.99 0.91 0.02 6.36 0.28

n = 119

Pool 26 52.94 1.13 0.63 0.02 8.32 0.29

n = 57

La Grange Pool 45.05 2.45 0.84 0.01 8.60 0.91

n = 57

Number of samples taken in each study area. a

Multiple comparison procedures (ANOVAs) revealed the average phosphorus content and nitrogen content

of plant tissues were not significantly different between pools. Phosphorus content mean was of 3.45 mg/g

(n = 37, SE = 0.21) and nitrogen content mean was 26.5 mg/g (n = 37, SE = 0.96). These levels are well above

critical levels for growth suggested by Gerloff and Krombolz (1966).

Pool 4

We found 16 species of SAV along Pool 4 transects during the spring sampling period and 15 during the

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

in the upper pool (above Lake Pepin; Appendix B). Species with the highest frequencies during both sampling

periods were coon's tail, wild celery, water stargrass, and Canadian waterweed. These four species made up

more than 50% of the relative frequencies. Sago pondweed, curly pondweed, and the small and leafy

pondweeds all declined in frequency and relative frequency between sampling periods (Table 6). 
14

Table 6. Frequencies and relative frequencies (%) of species found in Pool 4 during 1991 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Coon's tail 33.5 29.4 19.3 23.6

Curly pondweed 14.9 1.3 7.0 0.6

Canadian waterweed 17.0 14.2 8.9 10.4

Eurasian watermilfoil 6.8 9.3 2.6 5.5

Flatstem pondweed 9.1 7.8 3.4 4.3

Longleaf pondweed 1.6 2.3 0.7 1.5

Nodding waternymph 2.0 1.7 0.9 1.2

Sago pondweed 28.1 11.9 15.4 6.7

Small and leafy pondweeds 27.9 6.7 16.6 4.2

Water stargrass 15.7 18.6 7.3 12.9

Wild celery 27.5 30.5 17.2 28.8

Other species 1.3 1.0 0.6 0.3 b c b c

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

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

Other species include Richardson's pondweed, horned pondweed, common bladderwort, chara, and nitella. b

Other species include Richardson's pondweed, horned pondweed, chara, and nitella. c

Three species, sago, small and leafy, and curly pondweeds declined in most locations where present

between the spring and summer sampling periods. Because spring sampling was done later than planned (early

to mid-June in Pool 4), we probably caught peak growth for the pondweeds. If sampling had been done earlier,

before the pondweeds had reached their peak, the change may not have been so apparent. No other species

revealed significant change between sampling periods at locations where present. Only three species, coon’s

tail, curly pondweed, and sago pondweed, were found in transect locations above Lake Pepin. Most other

species were distributed throughout transect locations within the lower pool. Nitella and chara were found only

in the Big Lake area, whereas Richardson’s pondweed was found only in Robinson Lake (Table 7).

Pool 8

We found eight species along Pool 8 transects during the spring sampling period and four of the eight

species at the same transect locations during the summer sampling period. One additional species, longleaf

pondweed, was found at Goose Island, which was surveyed only during the summer sampling period

(Appendix B). Coon's tail and sago pondweed were the only two species with frequencies greater than 10%

and they accounted for nearly 90% of the relative frequencies during the spring sampling period. As in Pool 4,

sago pondweed dropped in frequency and relative frequency by the summer sampling period. Wild celery and

common bladderwort were rarely encountered in the spring and not found during the summer sampling period

(Table 8). No additional species were encountered during informal surveys that were not found

along transects.
15

Table 7. Pool 4 transect locations where species were present in the 1991 showing increase or decrease in species

between 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 Peterson Lake

Lower Peterson Lake

Big Lake

Big Lake Bay 

Robinson Lake

Rice Lake

Chara Big Lake

Rice Lake

Common bladderwort Big Lake

Coon's tail Peterson Lake

Lower Peterson Lake

Big Lake

Big Lake Bay

Robinson Lake

Bay City Flats

Dead Slough Lake

Mud Lake

Goose Lake

Rice Lake

Curly pondweed Lower Peterson Lake Big Lake Bay 

Peterson Lake Mud Lake

Big Lake Bay City Flats 

Robinson Lake Goose Lake

Eurasian watermilfoil Big Lake 

Peterson Lake

Lower Peterson Lake

Robinson Lake

Rice Lake

Flatstem pondweed Big Lake

Big Lake Bay 

Robinson Lake

Peterson Lake

Lower Peterson Lake

Horned pondweed Robinson Lake

Peterson Lake

Lower Peterson Lake

Big Lake

Longleaf pondweed Big Lake

Robinson Lake

Rice Lake

Nitella Big Lake

Nodding waternymph Big Lake Bay 

Robinson Lake

Big Lake 

Rice Lake

Richardson’s pondweed Robinson Lake

Sago pondweed Peterson Lake Big Lake

Lower Peterson Lake Mud Lake

Robinson Lake Rice Lake

Bay City Flats

Dead Slough Lake

Goose Lake
Table 7. Continued.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a b a

16

Small and leafy pondweeds Peterson Lake Rice Lake

Lower Peterson Lake

Big Lake

Big Lake Bay

Robinson Lake

Water stargrass Peterson Lake

Lower Peterson Lake

Big Lake 

Big Lake Bay

Robinson Lake

Rice Lake

Wild celery Big Lake Robinson Lake

Big Lake Bay

Peterson Lake

Lower 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 periods. b

Table 8. Frequencies and relative frequencies (%) of species at transect locations in Pool 8 during the 1991 spring

and summer sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 2.1 – 1.6 –

b

Coon's tail 59.9 0.6 65.6 12.5

Common bladderwort 0.3 – 0.1 –

Curly pondweed 3.1 1.3 2.8 37.5

Eurasian watermilfoil 0.8 1.0 0.5 18.7

Flatstem pondweed 6.2 – 4.6 –

Sago pondweed 29.4 1.6 24.3 31.2

Wild celery 0.3 – 0.4 –

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

Whereas no species significantly increased between sampling periods at any one location, several species

decreased. Sago pondweed, flatstem pondweed, and coon's tail all decreased significantly in Lawrence Lake.

Sago pondweed and coon's tail decreased in Target Lake and curly pondweed decreased at Shady Maple.

Common bladderwort and wild celery were found only in Target Lake, whereas flatstem pondweed was found

only in Lawrence Lake (Table 9).
17

Table 9. Pool 8 transect locations where species were present in 1991 showing increase or decrease in species

between 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 Lawrence Lake

Target Lake

Common bladderwort Target Lake

Coon's tail Target Lake

Lawrence Lake Shady Maple

Curly pondweed Shady Maple Lawrence Lake

Eurasian watermilfoil

Shady Maple

Target Lake

Lawrence Lake

Flatstem pondweed Lawrence Lake

Sago pondweed

Lawrence Lake

Target Lake Shady Maple

Wild celery 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

Pool 13

 We found eight species along Pool 13 transects during the 1991 spring sampling period and seven of those

species were found during the summer sampling period. Water stargrass was probably present, which would

add one species to the count for each sampling period, but a distinction between water stargrass and flatstem

pondweed was not made while in the field. Sago pondweed was the most frequently found species during both

the spring and summer sampling periods, but as in Pools 4 and 8, it decreased in frequency between periods

(Table 10). The remaining species were present at frequencies less than 10% during both the spring and

summer sampling periods.

Table 10. Frequencies and relative frequencies (%) of species in Pool 13 during the 1991 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Coon's tail 9.4 4.8 9.1 14.6

Curly pondweed 2.0 0.5 1.6 0.9

Eurasian watermilfoil 8.0 4.3 6.9 9.1

Longleaf pondweed 3.1 1.6 2.6 4.1

Nodding waternymph – 0.3 – 0.5 b

Sago pondweed 55.4 23.2 73.1 60.3

Small and leafy pondweeds 0.3 – 0.2 –

Wild celery 7.4 3.7 6.3 10.5

Other species 0.3 – 0.2 –

c

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

during the growing season.

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

Other species include flatstem pondweed and possibly water stargrass. c
18

Sago pondweed decreased at four of the eight locations where it was present. Coon’s tail decreased at one

of the six locations where it was found in the spring. No other species changed significantly (Table 11).

Table 11. Pool 13 transect locations where species were present in the 1991 showing increase or decrease in species

between 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

Coon's tail Johnson Creek Levee Potter's Marsh

Pomme de Terre

Brown's Lake

Curly pondweed Potter's Marsh

Pomme de Terre

Brown's Lake

Eurasian watermilfoil Johnson Creek Levee

Potter's Marsh

Pomme de Terre

Flatstem pondweed Johnson Creek Levee

Potter's Marsh

Pomme de Terre

Longleaf pondweed Pomme de Terre

Brown's Lake

Johnson Creek Levee

Nodding waternymph Pomme de Terre

Sago pondweed Johnson Creek Levee 

Potter's Marsh

Pomme de Terre

Brown's Lake

Small and leafy Pomme de Terre

 pondweeds

Wild celery Johnson Creek Levee

Potter's Marsh

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 sampling period and five of those

species during the summer sampling period. During the summer sampling period, we sampled along only 3 of

the 11 transects in Swan Lake after discovering the bed of sago pondweed had disappeared between sampling

periods. Also, sampling was limited in Stump Lake during the summer because of low water levels. Frequency

and relative frequency analysis include only those locations (and transects) that were monitored twice.

Relative frequencies were dominated by coon's tail and sago pondweed. Sago pondweed had the highest

relative frequency during the spring sampling period and coon’s tail had the highest relative frequency during

the summer sampling period. By the summer sampling period, the frequency of sago pondweed had decreased

and that of coon's tail had increased to the highest of all species found (Table 12). Informal surveys conducted

in July revealed no additional species that were not found along transects.
19

Table 12. Frequencies and relative frequencies (%) of species in Pool 26 during the 1991 spring and summer

sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Canadian waterweed 0.4 – 0.3 –

b

Coon's tail 17.3 44.8 30.9 83.9

Curly pondweed 0.5 1.6 0.4 1.6

Longleaf pondweed 4.2 0.4 8.1 0.4

Sago pondweed 33.5 5.8 55.4 13.8

Small and leafy pondweeds 8.1 0.4 4.8 0.4

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

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

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

Sago pondweed decreased significantly during the growing season (z-test; Table 13). Sago pondweed was

found uprooted and laying on the shoreline of Swan Lake. Coon's tail was the only species that increased. 

Table 13. Pool 26 transect locations where species were present in the 1991 showing increase or decrease in species

between 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 Calhoun Point

Coon's tail Calhoun Point

Curly pondweed Calhoun Point

Longleaf pondweed Stump Lake

Sago pondweed Swan Lake

Small and leafy Calhoun Point

 pondweeds

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

La Grange Pool

We found five species of submersed aquatic macrophytes along La Grange Pool transects during the 1991

spring and summer sampling periods. (One additional species, longleaf pondweed, was found in Banner

Marsh, which was sampled only during the summer sampling period.) Species frequencies in La Grange Pool

were dominated by Eurasian watermilfoil and coon's tail. Eurasian watermilfoil has been a problem species

in Spring Lake, covering most the water surface in the lower half of the lake where transects are located. In

that location, frequencies of Eurasian watermilfoil occupied at least 79% of sites where sampling was

performed (Table 14). 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.
20

Table 14. Frequencies and relative frequencies (%) of species in La Grange Pool, Illinois River, during 1991

spring and summer sampling periods.

Frequencies Relative frequencies a a

Species Spring Summer Spring Summer

Chara 11.4 9.1 9.6 8.6

Coon's tail 11.4 31.8 7.0 23.5

Eurasian watermilfoil 80.7 79.5 82.7 66.6

Sago pondweed 0.8 2.3 0.3 0.3

Western waterweed 0.9 0.7 0.3 0.9 b

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

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

Pending identification. b

Coon's tail was the only species that revealed a seasonal increase at La Grange Pool. Eurasian watermilfoil

remained stable in Spring Lake. The less frequently found sago pondweed and western waterweed also did not

change (Table 15).

Submersed aquatic macrophytes are rare in La Grange Pool, except in isolated backwaters. We found,

however, a few small patches of sago pondweed on the southeast side of Grape Island. These patches were on

fine sands with clay in water less than 0.10 m deep.

Table 15. La Grange Pool, Illinois River, transect locations where species were present in 1991 showing increase or

decrease in species between 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

Banner Marsh

Coon's tail Point Lake Spring Lake

Eurasian watermilfoil Spring Lake

Longleaf pondweed Banner Marsh

Sago pondweed Point Lake

Banner Marsh

Western waterweed Spring Lake c

Banner Marsh

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

Pending identification. c

Acknowledgments

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

thank the team leaders and staff at the participating agencies: 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.
21

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Gerloff, G. C., and P. H. Krombholz. 1966. Tissue analysis as a measure of nutrient availability for the growth

of angiosperm aquatic plants. Limnology and Oceanography 11:529–537.

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

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A-1

Appendix A

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

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

Pool of the Illinois River During the 1991 Sampling Season

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

Number of of sites of sites sampled sampled between

Number Number Dates Dates Distance

summer

Pool 4

Dead Slough Lake 9 98 93 6/17–18 8/7–8 30

(M789.2, M788.5,

M788.0)a

Goose Lake 3 25 25 6/20 8/6 30

(M788.G)b

Mud Lake 3 63 58 6/11 8/6 30

(M791.3)

Bay City Flats 3 77 74 6/20–21 8/9 30

(M788.0;

Catherine Pass)c

Robinson Lake 9 199 180 6/27–28; 8/14–16 30

(M788.R) 7/1–2 b

Big Lake Bay 3 22 48 7/3 8/19 30

(M788.5)

Rice Lake 3 27 24 7/3 8/19 30

(M758.0)

Big Lake 5 182 177 7/5, 8–10 8/20–21 30

(M757.5)

Peterson Lake 6 70 61 6/24–25 8/12 30

(M754.8, M754.5)

Lower Peterson Lake 4 94 119 6/24 8/13 30

(M753.5)

Total Pool 4 48 857 859 19 14

Pool 8

Target Lake 8 79 79 6/4–6 8/5, 7 15

(M696.0)

Goose Island 5 (summer) not sampled 80 not sampled 8/21–22 15

(M692.0)

Lawrence Lake 13 (spring) 195 195 5/30; 6/3, 8/9, 12–14 15

(M691.0) 10 (summer) 11–13, 20, 24

Shady Maple 3 24 30 6/17 8/20, 30 15

(M690.0)
Location transects in spring in in spring in summer sites (m)

Number of of sites of sites sampled sampled between

Number Number Dates Dates Distance

summer

A-2

Horseshoe HREP 5 (summer) not sampled 40 not sampled 8/15 15 d

(M687.0)

Total Pool 8 24 (spring) 298 424 10 11

31 (summer)

Pool 13

Brown's Lake 25 194 235 6/24–26; 8/5, 15, 15 or 30

(M545.1, M544.5) 7/1–2 26–27

a

Savanna Bay 12 (summer) not sampled 120 not sampled 8/28; 9/4 15

(M541.5, M540.5,

M539.5)

Spring Lake 12 (summer) not sampled 99 not sampled 8/8, 28 15

(M534.8, M533.6,

M532.0)

Pomme de Terre 5 52 59 7/3 8/6 15

(M526.0)

Potter's Marsh 6 41 41 7/9–10 8/21 15

(M524.0)

Johnson Creek Levee 4 55 40 7/10 8/22 15

(M523.5)

Lower Johnson Creek 2 (summer) not sampled 30 not sampled 8/22 15

(M523.0)

Total Pool 13 60 (spring) 342 624 9 12

94 (summer)

Pool 26

Calhoun Point 21 137 137 6/10–13, 8/8 15

(I003.0) 17–18 e,f

Swan Lake 11 (spring) 308 80 6/25, 28; 8/12 15

(I005.5) 3 (summer) 7/1, 3, 8,

10–12

Stump Lake 8 (spring) 172 24 7/16–17, 20 not sampled 15

(I010.0)

Total Pool 26 40 (spring) 617 241 15 12

32 (summer)

La Grange Pool

Point Lake 6 9 20 7/17, 24 8/21 15

(I100.0)
Location transects in spring in in spring in summer sites (m)

Number of of sites of sites sampled sampled between

Number Number Dates Dates Distance

summer

A-3

Spring Lake 5 105 99 6/13, 19–20, 8/8–9, 16, 20 15

(I135.5) 26–28;

7/11–12

Banner Marsh 2 13 13 7/31 8/19 15

(I140.7;

Bulrush Pond )

c

Total La Grange 13 127 132 10 6

Pool

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 Mississippi and Illinois 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 –

b c

Chara (Chara spp.) x – – – x

Common bladderwort

(Utricularia macrorhiza L.) x x – – –

Coon's tail

(Ceratophyllum demersum L.) x x x x x

Curly pondweed

(Potamogeton crispus L.) x x x x –

Eurasian watermilfoil lower pool

(Myriophyllum spicatum L.) x x x – x

Horned pondweed lower pool

(Zannichellia palustris L.) x – – – –

Flatstem pondweed lower pool

(Potamogeton zosteriformis Fern) x x x – –

Longleaf pondweed

(Potamogeton nodosus Poiret.) x x x x x

Nitella (Nitella spp.) x – – – –

Nodding waternymph lower pool

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

Schmidt)

Richardson’s pondweed lower pool

(Potamogeton richardsonii [Benn] x – – – –

Rydb.)

Sago pondweed

(Potamogeton pectinatus L.) x x x x x

Small and leafy pondweeds

(Potamogeton pusillus and lower pool

P. foliosus L.) x – x x –

Water stargrass lower pool

(Heteranthera dubia L.) x – ? – – –

d

Western waterweed

(Elodea Nuttallii [Planch.] St. John) – – – – x

Wild celery, American eelgrass lower pool

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

La Grange

B-2

Floating-leaved Species

American lotus

(Nelumbo lutea [Willd.] Pers.) x x x – –

White waterlily

(Nymphaea odorata Ait.) x x – – –

Yellow pondlily

(Nuphar lutea [L.] Sm.) – – – – –

Species of submersed plants found during informal surveys but not found along transects

Northern watermilfoil

(Myriophyllum sibericum Komarov) x

Total per pool 19 11 10 6 6

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

The symbol "x" indicates the species was present. b

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

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

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

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

June 1998

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

1991 Annual Status Report: A summary of 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 , Daniel Dieterman , Heidi Langrehr , John Nelson , and Susan Romano-Peitzmerer 1 2 3 4 5 5

7. PERFORMING ORGANIZATION NAME AND ADDRESS 8. PERFORMING ORGANIZATION

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

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

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

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

and

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

 REPORT NUMBER

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

U.S. Geological Survey 

Environmental Management Technical Center 98-P005

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). 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).

13. ABSTRACT (Maximum 200 words)

The Long Term Resource Monitoring Program (LTRMP) of the Upper Mississippi River System (UMRS) authorizes monitoring of submersed aquatic vegetation (SAV)

in the river system. This report summarizes the 1991 effort of monitoring SAV along transects permanently established in vegetated locations in four navigation pools

of the Upper Mississippi River and one navigation pool of the Illinois River. Seventeen species of submersed aquatic plants were found along transects in Pools 4, 8,

13, and 26 and La Grange Pool. The highest number of submersed aquatic plant species found in any one pool was 16 in Pool 4 and the lowest number was 6 in La

Grange Pool. Coon’s tail (Ceratophyllum demersum) and sago pondweed (Potamogeton pectinatus) were the only two species found in every study pool during

both spring and summer sampling. Decreases in pondweed species noticeably affected the number of transect sites with SAV in Pools 4 and 13. In Pool 8, nearly all

species declined between sampling periods and the proportion of sites with SAV dropped to less than 10% by August, the most decline of any pool. 

14. SUBJECT TERMS 15. NUMBER OF PAGES

1991 annual report, aquatic, Illinois River, LTRMP, Mississippi River, monitoring, plant, submersed, vegetation 21 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.