Long Term Resource Monitoring Program

Program Report

98-P012

1996 Annual Status Report

A Summary of Aquatic Vegetation Monitoring at

Fixed Transects in Pools 4, 8, 13, and 26 and

La Grange Pool of the Upper Mississippi River System

September 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

 ACTINGDIRECTOR

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 
1996 Annual Status Report

A Summary of Aquatic Vegetation Monitoring at

Fixed Transects 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

Heidi Langrehr and J. Therese Dukerschein

Wisconsin Department of Natural Resources

Onalaska Field Station

575 Lester Avenue

Onalaska, Wisconsin 54650

Jenny Winkelman

Minnesota Department of Natural Resources

1801 South Oak Street

Lake City, Minnesota 55041

John Nelson

Illinois Natural History Survey

Alton Field Station

4134 Alby Street

Alton, Illinois 62002

Theresa Blackburn

Iowa Department of Natural Resources

Mississippi River Monitoring Station

206 Rose Street

Bellevue, Iowa 52031

Thad Cook

Illinois Natural History Survey

Havana Field Station

704 North Schrader Avenue

Havana, Illinois 62644

November 1998
Suggested citation:

Rogers, S., H. Langrehr, J. T. Dukerschein, J. Winkelman, J. Nelson, T. Blackburn, and T. Cook. 1998. 1996 annual status

report: A summary of aquatic vegetation monitoring at fixed transects 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, November 1998. LTRMP 98-P012. 23 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

Informal Surveys .............................................................. 7

Environmental Factors .......................................................... 7

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

Results and Discussion ............................................................. 9

All Pools ..................................................................... 9

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

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

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

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

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

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

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

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

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

Tables

Table 1. Area and relative proportions of aquatic habitats (based on geomorphology) by navigation

pool for select reaches of the Upper Mississippi River System studied as part of the Long

Term Resource Monitoring Program ......................................... 3

Table 2. Frequency (%) of aquatic plant species sampled in Pools 4, 8, 13, and 26 of the Upper

Mississippi River and La Grange Pool (LG) of the Illinois River, 1996 ............. 10

Table 3. Frequency of vegetated sites with submersed aquatic plant species along transects in Pools 4,

8, 13, and 26 of the Upper Mississippi River and La Grange Pool of the Illinois River during

spring and summer sampling, 1996 ......................................... 12
iv

Table 4. Maximum rooting depths of submersed aquatic plant species in Pools 4, 8, 13, and 26 of the

Upper Mississippi River and La Grange Pool of the Illinois River during spring and summer

sampling, 1996 ......................................................... 12

Table 5. Frequencies and relative frequencies of submersed aquatic plant species found along

transects in Pool 4 of the Upper Mississippi River during spring (May 22–June 13) and

summer (July 18–August 15) sampling periods, 1996 ........................... 13

Table 6. Seasonality of submersed aquatic plant species sampled along transects in backwaters of

Pool 4, Upper Mississippi River, 1996 ...................................... 14

Table 7. Frequencies and relative frequencies of submersed aquatic plant species found along

transects in Pool 8 of the Upper Mississippi River during spring (May 20–June 13) and

summer (July 15–August 12) sampling periods, 1996 ........................... 15

Table 8. Seasonality of submersed aquatic plant species sampled along transects in backwaters of

Pool 8 of the Upper Mississippi River, 1996 .................................. 16

Table 9. Frequencies and relative frequencies of submersed aquatic plant species found along

transects in Pool 13 of the Upper Mississippi River during spring (May 21–June 19) and

summer (July 19–August 21) sampling period, 1996 ............................ 17

Table 10. Seasonality of submersed aquatic plant species sampled along transects in backwaters of

Pool 13 of the Upper Mississippi River, 1996 ................................. 18

Table 11. Frequencies and relative frequencies of submersed aquatic plant species found along

transects in Pool 26 of the Upper Mississippi River during spring (June 5–13) and summer

(August 2–8) sampling periods, 1996 ....................................... 20

Table 12. Seasonality of submersed aquatic plant species sampled along transects in backwaters of

Pool 26 of the Upper Mississippi River, 1996 ................................. 20

Table 13. Frequencies and relative frequencies of submersed aquatic plant species found along

transects in La Grange Pool of the Illinois River during spring (May 22–30) and summer (July

17–August 1) sampling periods, 1996 ....................................... 20

Table 14. Seasonality of submersed aquatic plant species sampled along transects in backwaters of La

Grange Pool of the Illinois River, 1996 ...................................... 21

Figures

Figure 1. Location of Navigation Pools 4, 8, 13, and 26 and La Grange Pool in the Upper Mississippi

River System where aquatic vegetation was surveyed, Long Term Resource Monitoring

Program, 1996 .......................................................... 3

Figure 2. Backwater locations in Pool 4 (Upper Mississippi River) where transects were monitored for

aquatic vegetation, Long Term Resource Monitoring Program, 1996 ................ 4
v

Figure 3. Backwater locations in Pool 8 (Upper Mississippi River) where transects were monitored for

aquatic vegetation, Long Term Resource Monitoring Program, 1996 ................ 5

Figure 4. Backwater locations in Pool 13 (Upper Mississippi River) where transects were monitored

for aquatic vegetation, Long Term Resource Monitoring Program, 1996 ............. 5

Figure 5. Backwater locations in Pool 26 (Upper Mississippi River) where transects were monitored

for aquatic vegetation, Long Term Resource Monitoring Program, 1996 ............. 5

Figure 6. Backwater locations in La Grange Pool (Illinois River) where transects were monitored for

aquatic vegetation, Long Term Resource Monitoring Program, 1996 ................ 6

Figure 7. Daily water surface elevations for select navigation pools of the Upper Mississippi River

system ................................................................ 8
vi

Preface

The Long Term Resource Monitoring Program (LTRMP) was authorized under the Water Resources

Development Act of 1986 (Public Law 99-662) as an element of the U.S. Army Corps of Engineers'

Environmental Management Program. The LTRMP is being implemented by the Environmental Management

Technical Center (EMTC). 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 and river managers 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 (U.S. Fish and

Wildlife Service 1993).

 This report presents the results of aquatic vegetation transect surveys conducted in 1996 by field station

personnel under the direction of the EMTC. 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 1996, 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 1996. This report was developed with funding provided by the Long Term Resource Monitoring

Program. 
1996 Annual Status Report

A Summary of Aquatic Vegetation Monitoring at

Fixed Transects in Pool 4, 8, 13, and 26 and

La Grange Pool of the Upper Mississippi River System

by

Sara Rogers, Heidi Langrehr, J. Therese Dukerschein, Jenny Winkelman,

John Nelson, Theresa Blackburn, and Thad Cook

Abstract

Distribution and frequency of submersed aquatic vegetation in the Upper Mississippi River System are monitored

as part of the Long Term Resource Monitoring Program. This report summarizes results of sampling aquatic

vegetation along fixed transects in Navigation Pools 4, 8, 13, and 26 in the Upper Mississippi River and

La Grange Pool in the Illinois River in 1996. Plants were sampled at regular intervals along fixed transects using

a modified rake technique. Sampling was conducted twice during the growing season (spring and summer).

Twenty-four submersed and rooted floating-leaved species were found. Most species were found in Pools 4, 8,

and 13. Pool 26 had the fewest (3) number of species and Pool 4 had the greatest (23), including most largeleaved pondweeds and the first LTRMP record of floating pondweed (Potamogeton natans). Sago pondweed

(P. pectinatus) and coontail (Ceratophyllum demersum) were dominant in the contiguous backwaters sampled.

Seasonal trends were observed in nine species, all of which, except sago pondweed, increased later in the season.

Throughout the growing season, more sites were vegetated in Pools 8 and 13 and La Grange Pool (frequency of

50–73%) than in Pools 4 and 26 (<25%). Pool 26 was devoid of vegetation during the second sampling. Aquatic

vegetation was generally rare in contiguous areas of Pool 26 and La Grange Pool, but more plentiful in the

isolated, managed backwaters of La Grange Pool.

Introduction

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

Resource Monitoring Program (LTRMP; U.S. Fish and Wildlife Service 1993). The distribution and

frequency 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 water quality, fish, and invertebrate monitoring, the overall mission of the Program is to provide

scientifically sound and useful information for effective river management. The purpose of this report is to

document the results of transect sampling at selected locations in 1996. 

Historically, submersed aquatic vegetation (SAV) has played an important role in the UMRS ecosystem.

These plant communities provide food for migratory waterfowl (Korschgen et. al. 1988) and improvement

of water quality by stabilizing sediments, filtering out suspended materials, and taking up nutrients that can

otherwise support nuisance algal growth (Barko et al. 1991). Macrophytes also provide nursery areas for

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

surface area (Engel 1990).

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

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

and concern for this important resource, however, especially in view of the drastic decline of SAV in the

Illinois River in the 1950s, of which only remnant populations survive (Talkington and Semonin 1991).

Concern for SAV in the Upper Mississippi River escalated in the mid- to late-1980s when widespread and

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

(E. Nelson and C. Cheap, U.S. Fish and Wildlife Service, Winona, Minnesota, unpublished data; C.
2

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, Wisconsin, personal communication).

Long-term monitoring can play a substantial role in increasing an 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?

This report documents the results of sampling of submersed and rooted floating-leaved vegetation along

transects at selected locations in 1996. It provides baseline information to evaluate changing conditions. The

1996 growing season was the sixth year that we conducted field surveys in designated LTRMP study reaches.

The objectives for monitoring aquatic vegetation in the UMRS are to

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

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

(3) identify environmental factors that may influence both long- and short-term changes in the

distribution and abundance of SAV.

Fulfillment of these objectives requires research in addition to monitoring.

Study Areas

The LTRMP vegetation study area consists of five reaches within the UMRS, four on the Upper

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

pool designations according to the U.S. Army Corps of Engineers (USACE) lock and dam system. The Upper

Mississippi River navigation pools studied are Pool 4 (Mississippi River mile [M] 752 to 797), Pool 8

(M 679 to 703), Pool 13 (M 523 to 557), Pool 26 (M 202 to 242), and La Grange Pool of the Illinois River

(Illinois River mile [I] 80 to 158). Pool 26 includes 12 miles of the lower Illinois River upstream of its

confluence (M 218) with the Upper Mississippi River. River miles for the Upper Mississippi River are

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

of the Mississippi and Illinois Rivers.

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

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

geomorphically complex with contiguous and isolated backwaters and numerous interconnected channels

(Table 1). A relatively large proportion of the aquatic area in these pools comprise backwaters and

impounded areas. The upper portions retain the most riverine character with braided channels, forested

islands, and a relatively large range of water-level fluctuations (Peck and Smart 1986). In contrast, the lower

portions of these pools provide a shallow, more lacustrine environment. Pool 26 has a greater proportion of

main channel area. La Grange Pool has a high percentage of contiguous backwaters, but very little SAV has

been observed. Consequently, SAV sampling effort is less intensive in the two southern pools.
3

Figure 1. Location of Navigation Pools 4, 8, 13, and 26 and La Grange Pool in the

Upper Mississippi River System where aquatic vegetation was surveyed, Long Term

Resource Monitoring Program, 1996. The Open River Reach (Mississippi River mile

0 to 80), where water quality, fish, and invertebrates are sampled as part of the Long

Term Resource Monitoring Program, is not monitored for vegetation because of the

lack of habitat for submersed aquatic vegetation.

Table 1. Area and relative proportions of aquatic habitats (based on geomorphology) by navigation pool for select

reaches of the Upper Mississippi River System studied as part of the Long Term Resource Monitoring Program.a

Main Side

channel channel Backwate Lake Impounded Isolated

r

Location (ha) % (ha) % (ha) % (ha) % (ha) % (ha) % (ha)

Area Area Area Area Area Area Total area

Pool 4 1,240 8 721 5 2,300 16 9,764 66 0 0 660 5 14,685 b

Pool 8 1,256 16 1,380 17 1,767 22 0 0 3,476 43 124 2 8,003

Pool 13 2,700 27 805 8 2,810 28 0 0 3,560 36 116 1 9,991

Pool 26 4,860 57 1,496 18 415 5 948 11 176 2 580 7 8,475 c

La Grange Pool 2,398 22 143 1 5,676 51 0 0 0 0 2,835 26 11,052 d

Data for Pools 4, 8, 13, and 26 were based on the sampling strata coverage. Data for La Grange Pool were based on the aquatic a

areas coverage.

Refers to Lake Pepin, a tributary delta lake. b

Refers to Swan Lake. c

La Grange Pool is located on the Illinois River. d
4

Figure 2. Backwater locations in Pool 4 (Upper Mississippi River) where transects were

monitored for aquatic vegetation, Long Term Resource Monitoring Program, 1996.

In Pool 4, we surveyed contiguous backwaters where transects were established in 1991 (Figure 2).

Transects 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, Mud Lake, and Catherine Pass

(referred to as Bay City Flats in previous reports; Appendix A). Upper Mud Lake, which was added in 1993,

was surveyed only during the spring sampling period. Transect sampling was discontinued in Upper Mud

Lake because it is semi-isolated, atypical of backwaters in upper Pool 4, and access and sampling can be

difficult. Instead, Upper Mud Lake was adopted as a fixed location for qualitative (informal) surveys. Lower

pool locations (below Lake Pepin) included Robinson Lake and Peterson Lake, as well as three that are part

of the Big Lake area, Big Lake, Rice Lake, and Big Lake Bay. In 1996, an additional transect was placed in

upper Big Lake to capture dynamic changes in SAV. Data collected along thistransect were excluded from

analysis. A Habitat Rehabilitation and Enhancement Project (HREP), which involved dredging part of

Big Lake Bay, was completed in spring 1993. The construction of a HREP in Peterson Lake in fall 1995

required relocating the first transect approximately 30 m downstream.

In Pool 8, we sampled five backwaters where transects were established in 1991 (Figure 3). Locations

included Target Lake, Lawrence Lake, a backwater area near Goose Island, Shady Maple, and the interior

of Horseshoe Island (Appendix A). We added a backwater near Stoddard, Wisconsin, in 1992, and two

backwaters, Blue Lake and the interior of Boomerang Island, in 1993. Horseshoe Island and Boomerang

Island are part of the Pool 8 Islands HREP. Most backwaters were located in the lower two thirds of the pool.

In Pool 13, we monitored seven backwaters where transects were established in 1991 (Figure 4). Most

of the backwaters were located in the middle and lower portions of the pool and included Brown's Lake,

Savanna Bay, Spring Lake, Pomme de Terre, Potter's Marsh, Johnson Creek, and Johnson Creek Levee

(Appendix A). Brown’s Lake and Potter’s Marsh are part of HREPs initiated in 1988 and 1994, respectively.
5

Figure 4. Backwater locations in Pool 13

(Upper Mississippi River) where transects

were monitored for aquatic vegetation, Long

Term Resource Monitoring Program, 1996.

Figure 3. Backwater locations in Pool 8

(Upper Mississippi River) where transects

were monitored for aquatic vegetation,

Long Term Resource Monitoring Program,

1996.

Figure 5. Backwater locations in Pool 26 (Upper Mississippi River)

where transects were monitored for aquatic vegetation, Long Term

Resource Monitoring Program, 1996.

In Pool 26, we surveyed two backwaters where transects were established in 1991 (Figure 5). These

backwaters included Stump Lake and the Calhoun Point area, which consists of several backwater lakes,

sloughs, and ephemeral ponds (Appendix A). We also surveyed Fuller Lake, which was added in 1992. The

HREP construction in Swan Lake, which was sampled in previous years, prevented vegetation sampling in

1996. Before the HREP implementation, only Swan Lake was contiguous with the main river. The other

transects were located in isolated backwaters that are intensively managed as moist soil units (namely, to

mimic pre-impoundment hydrology). The reach known as Pool 26 includes portions of the Upper Mississippi

River and lower Illinois River. All backwater locations sampled for vegetation were found in the lower

12 miles of the Illinois River.
6

Figure 6. Backwater locations in La Grange Pool (Illinois River) where transects were

monitored for aquatic vegetation, Long Term Resource Monitoring Program, 1996.

In La Grange Pool, we have sampled three backwaters since 1991 (Figure 6); Bulrush Pond in the Banner

Marsh State Fish and Wildlife Area, Point Lake, and Spring Lake (Appendix A). The Grape Island area,

which was added in 1992, was sampled only in the summer in 1996. High water in the spring prevented

sampling. Water levels in the main river influence the Grape Island area and Point Lake, but not Spring Lake

and Banner Marsh, which are behind large drainage district levees.

Methods

Transect Sampling

Transects were positioned perpendicular to shorelines at regular intervals, from 50 to 200 m apart

depending on the size of the area. Transects typically traversed an entire backwater. Sampling was performed

twice in most locations during the growing season in order to observe seasonal changes. In 1996, spring

sampling began on May 20 and ended June 19. The summer sampling period extended from July 15 to

August 21 (Appendix A). Two sites were sampled only once during 1996, Upper Mud Lake in Pool 4 (Upper

Mississippi River) and Grape Island in La Grange Pool (Illinois River).

In 1996, we considered water temperature and calendar date in determining the onset of spring sampling.

Ideally, sampling would proceed when temperatures in the backwaters reached 18E C, which exceeds the

threshold for SAV growth and elongation (Barko and Smart 1981; Madsen and Adams 1988; Flint and
7

Madsen 1995). In fact, sampling was initiated before the threshold was reached due to the prolonged cool

weather and the need to complete sampling by mid-June.

Sampling along the transects was conducted at regularly spaced intervals or sites. Sites were sampled

every 15 m in Pools 8, 13, and 26 and La Grange Pool, and every 30 m in Pool 4 due to the large size of some

backwaters. The sampling method was modified from a technique used by Jessen and Lound (1962). At each

site along a transect, a sampling area extending approximately 2 m from the front of the boat was divided

into thirds. We sampled plants once in each third by lowering a long-handled thatching rake to the bottom

and twisting it. The thatching rake had a 38.1-cm (15-inch) head with 20, 12.7-cm-long (5-inch) teeth and

sampled an area of approximately 0.1 m . The submersed species on the rake were identified and recorded.

2

After all three twists were made, each species retrieved was assigned a rating of 1 to 4, based on the number

of times it appeared on the rake. A rating of 4 was assigned only if a species completely covered the rake

teeth on all three twists.

If rooted floating-leaved species were present, they were assigned a rating of 1 to 4 based on the amount

of vegetative cover visible in the entire 2-m sampling area (1 = 1–25% cover, 2 = 26–50% cover, 3 = 51–75%

cover, and 4 = 76–100% cover). Rooted floating-leaved species were not used in calculating relative

frequency. Non-rooted floating species (e.g., Lemnaceae) were recorded if they exceeded 5% of the surface

area, but were excluded from analysis.

Fassett (1957), Voss (1972, 1985), and Gleason and Cronquist (1991) were the primary keys used for

plant identification. Scientific nomenclature and common names are based on those found in the U.S.

Department of Agriculture Internet PLANTS Database (http://plants.usda.gov/plants/). Leafy pondweed

(Potamogeton foliosus) and small pondweed (P. pusillus) were collectively referred to as “small and leafy

pondweeds.” They were not distinguished from each other during field sampling and were combined for

analysis. Watermilfoilspecies were considered to be Eurasian watermilfoil (Myriophyllum spicatum) unless

specifically recorded as short spike watermilfoil (M. sibiricum). Chara (Chara spp.), which is a macroalgae,

was analyzed together with the vascular plants.

Since sampling began in 1991, examples of species found in each pool have been saved as voucher

specimens. Voucher specimens have been pressed, dried, mounted, labeled, and stored at each field station.

Rare species and unusual specimens have been saved for reference and sent to outside experts for

verification. A list of submersed and floating-leaved species found during LTRMP monitoring since 1991

appears in Appendix B.

Informal Surveys

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

we qualitatively surveyed many portions within each study pool. When vegetation was observed, visually

or with the aid of a depth finder, we recorded species composition, relative abundance, approximate bed size,

water depth,substrate type, and location information. Informal surveys have not been conducted in Pool 26

since 1992, when extensive surveys revealed that SAV was generally scarce.

Environmental Factors

Water depth was recorded at each site. The maximum rooting depth was calculated by averaging the

deepest 10% of sites vegetated with SAV. Depths were not adjusted for water surface elevations (WSE),
8

which fluctuate due to water-level management and natural events. A qualitative sediment assessment based

on visual and tactile characteristics was recorded for each transect, but was excluded from analysis.

Daily WSE were measured by the USACE (Figure 7). Most backwaters with transects were in the middle

to lower sections of the pools, therefore, select mid-pool gage readings were used to produce stage

hydrographs for Pool 4 (Wabasha, Minnesota; M 760.4), Pool 8 (La Crosse, Wisconsin; M 696.8), Pool 26

(Grafton, Illinois; I 218.0), and La Grange Pool (Beardstown, Illinois; I 88.0). No mid-pool gage

measurements for 1996 were available for Pool 13, so no WSE data were included for Pool 13. Mid-pool

gages are preferred because most transects are located in that part of the pool. Similar stage hydrograph

patterns are observed along the length of a pool and ultimately depend on discharge, which determines how

pool level is controlled.

Statistical Analysis

The frequency of a species is defined as

f = j /n i i

where 

 j = number of sample sites containing species I on at least one of the three rake twists, i

 n = total number of sample sites.

Relative frequency of a species was defined as

rf = e /Ef i i

where

e = number of rake twists where species I was recorded, i

Ef = sum of the total number of samples of each species present.

Frequency was calculated on a per site basis (a site was considered vegetated if at least one of three rake

twists recovered plants); whereas, relative frequency calculations used each rake twist in order to assess the

relative proportion of each species. Frequency and relative frequency are expressed as percent. Records of

rooted floating-leaved species were omitted from the relative frequency calculations.

Chi-square tests were used to test for significant seasonal differences in the number of vegetated sites in

each pool. To test for significant change in the frequency of individual species between sampling periods,

a value for Z was calculated for each species in each backwater location 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 = j /n , 1 1 1

p = j /n , 2 2 2

n and n = 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.
Month

Water surface elevation (feet above mean sea level)

Pool 4 (Wabasha gage, M 760.4)

Pool 8 (La Crosse gage, M 696.8)

Pool 26 (Grafton gage, M 218.0)

La Grange Pool (Beardstown gage, I 88.0)

630

635

640

645

650

655

660

664

669

674

679

684

689

694

415

420

425

430

435

440

445

425

430

435

440

445

450

455

J ND FM A M A J J S O

J ND FM A M A J J S O

J ND FM A M A J J S O

J ND FM A M A J J S O

9

Figure 7. Daily water surface elevations for select navigation pools of the Upper Mississippi

River System. Solid line shows 1996 stage hydrograph. Dotted line indicates mean annual

stage hydrograph and shaded area shows minimum and maximum water surface elevations

for the period of record from 1950–1996 (Mississippi River mile [M]; Illinois River mile [I]; U.S.

Army Corps of Engineers data). Mid-pool gage data are not available for Pool 13.

Results and Discussion

All Pools

A total of 24 species of submersed and rooted floating-leaved plants were found in 1996 (21 and 3 species,

respectively; Table 2). Of these, 16 submersed species were found along transects, and the remainder were
10

recorded during informal surveys. Pool 4 was the most species rich (23, of which 20 were submersed) and

Pool 26 the most depauperate (3, of which 2 were submersed). A total of 12 species, including 10 submersed,

were recorded in La Grange Pool, Illinois River. As Peck and Smart (1986) noted, most species in the Upper

Mississippi River were found upstream of Pool 14.

Table 2. Frequency (%) of aquatic plant species sampled in Pools 4, 8, 13, and 26 on the Upper Mississippi River

and La Grange Pool (LG) of the Illinois River, 1996.

Spring Summer

Species 4 8 13 26 LG 4 8 13 26 LG

Submersed species

bladderwort, common IS 2.0 – – – – 2.5 – – –

(Utricularia macrorhiza)

a b

buttercup, longbeak IS – – – – – – – – –

(Ranunculus longirostris)

chara IS – – – – – – 0.2 – 10.3

(Chara spp.)

coontail 4.4 50.7 11.4 – 15.7 2.9 52.2 20.2 – 17.9

(Ceratophyllum demersum)

pondweed, alpine IS – – – – – – – – –

(Potamogeton alpinus)

pondweed, curly 8.6 17.0 1.2 – 12.4 1.3 10.0 1.7 – 18.8

(P. crispus)

pondweed, flatstem – 3.6 0.2 – – 0.1 4.4 1.1 – –

(P. zosteriformis)

pondweed, floating IS – – – – – – – – –

(P. natans)

pondweeds, small and leafy 0.5 16.2 0.1 – 3.4 0.5 19.3 0.4 – 20.5

(P. pusillus, P. foliosus)

pondweed, longleaf 0.4 0.7 1.5 1.3 2.2 0.2 1.6 2.2 – 6.0

(P. nodosus)

pondweed, ribbonleaf IS – – – – – – – – –

(P. epihydrus)

pondweed, Richardson’s IS – – – – – – – – –

(P. richardsonii)

pondweed, sago 14.3 29.6 40.0 11.6 6.7 4.8 29.6 32.1 – 6.8

(P. pectinatus)

pondweed, horned IS 0.2 – – – – 0.2 – – 8.5

(Zannichellia palustris)

water stargrass 0.2 0.1 6.8 – – 1.1 0.7 20.2 – –

(Heteranthera dubia)

watermilfoil, Eurasian 1.9 11.8 1.2 – 38.2 4.0 15.1 5.5 – 66.7

(Myriophyllum spicatum)

watermilfoil, shortspike 0.2 – – – – – – – – –

(M. sibiricum)

waternymph, nodding IS 0.1 – – – – 4.8 1.7 – 2.6

(N. flexilis)

waternymph, southern – – – – – – – 2.2 – –

(N. guadalupensis)

waterweed, Canadian 0.4 2.8 2.8 – – 1.5 4.0 3.9 – 3.4

(Elodea canadensis)

wild celery – – 6.4 – – 9.8 0.3 16.4 – –

(Vallisneria americana)
Table 2. Continued.

Spring Summer

Species 4 8 13 26 LG 4 8 13 26 LG

11

Number of submersed species 9 12 10 2 6 10 13 13 0 10

(transects)

Rooted floating-leaved species

American lotus – 0.4 9.2 5.2 2.2 3.8 19.0 40.1 – 7.7

(Nelumbo lutea)

pondlily, yellow IS 5.6 – – – – 4.3 – – –

(Nuphar lutea)

waterlily, white 3.0 35.8 1.9 – – 6.4 42.6 3.3 – 7.7

(Nymphaea odorata)

Number of rooted floating- 1 3 2 1 1 2 3 2 0 2

leaved species (transects)

Total number of species per 23 16 15 3 12

poolc

IS indicates a species was recorded during informal surveys but not during transect sampling. a

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

Includes data from spring and summer transects and from informal surveys. c

Sago pondweed (Potamogeton pectinatus), longleaf pondweed (P. nodosus), and American lotus

(Nelumbo lutea) were the most cosmopolitan species present in all pools (Table 2). Coontail (Ceratophyllum

demersum), curly pondweed (P. crispus), small and leafy pondweeds (P. pusillus and P. foliosus), Eurasian

watermilfoil (Myriophyllum spicatum), nodding waternymph (Najas flexilis), Canadian waterweed (Elodea

canadensis), and white waterlily (Nymphaea odorata) were found in all LTRMP study reaches except

Pool 26. Less common species were restricted in their distribution. Large-leaved pondweeds (P. alpinus,

P. epihydrus, P. richardsonii, and P. natans), longbeak buttercup (Ranunculus longirostris), and shortspike

watermilfoil (M. sibiricum) were recorded only in Pool 4, and southern waternymph (Najas guadalupensis)

was found only in Pool 13.

Sago pondweed was the most frequently found species in Pools 4, 13, and 26. Coontail was dominant in

Pool 8 transects, and Eurasian watermilfoil was most common in La Grange Pool. In general, sago pondweed

growth peaked in the spring and subsequently declined. Other taxa, such as chara (Chara spp.), small and

leafy pondweeds, water stargrass (Heteranthera dubia), Eurasian watermilfoil, waternymphs (Najas spp.),

wild celery, American lotus, and white waterlily increased in frequency later in the season.

Approximately 50–73% of the sites sampled in Pools 8, 13, and La Grange Pool were vegetated during

the 1996 growing season (Table 3). In comparison, vegetation was seen in <25% of the sites sampled in

Pools 4 and 26. During summer sampling, the Pool 26 backwaters with transects were devoid of both

submersed and floating-leaved vegetation. 

In all pools, the percent of sites with SAV changed significantly between sampling periods, but the

direction of change varied among pools (Table 3). Whether vegetation increased or decreased seasonally

could usually be attributed to the regional phenology of the most dominant species. For example, in Pools

4 and 26, the general drop in the percent of SAV sites reflected a summer decline in sago pondweed, as well

as in curly pondweed in Pool 4 (Table 2). Although wild celery later increased in Pool 4, it could not offset
12

the decline of sago and curly pondweeds. Conversely, the increase in vegetated sites in La Grange Pool

reflects the expansion of Eurasian watermilfoil.

Table 3. Frequency of vegetated sites with submersed aquatic plant species along transects in Pools 4, 8, 13, and

26 of the Upper Mississippi River and La Grange Pool of the Illinois River during spring and summer sampling, 1996.

Pool Spring (%) n Summer (%) n Significancea

 4 24.6 963 18.8 950 * P < 0.002 b

 8 73.4 1,293 65.4 1,252 * P < 0.001

13 49.1 985 56.2 996 * P < 0.002

26 12.3 310 0.0 166 * P < 0.001

La Grange 52.8 89 72.7 117 * P < 0.003 c

Probability value is based on Chi-square test where % = 0.05. The symbol “*” indicates significant change. a

Upper Mud Lake was excluded from calculations. b

Grape Island was excluded from calculations. c

In Pools 4, 8, and 13, the maximum rooting depth decreased from north to south (Table 4). Overall, the

maximum rooting depth of SAV was deepest in Pool 26 (3.0 m, spring) and shallowest in Pool 13 (0.9 m,

summer). In all study reaches, SAV grew deeper in the spring than in the summer. This trend reflects the

natural hydrograph where seasonal precipitation typically swells WSE in the springtime (Figure 7). In

Pools 4 and 8, the 1996 hydrographic pattern was characteristic, although higher than usual in the springtime.

For the second consecutive year, spring flooding in the Illinois River resulted in unusually high water levels

in Pool 26 and La Grange Pool. The hydrographic pattern indicates that water levels dropped during July.

The relatively deep growth of plants in La Grange Pool reflects seasonal high water, as well as control of

water levels for fish production. In Pool 26, the lack of SAV during summer sampling precluded

determination of rooting depth.

Table 4. Maximum rooting depths (m) of submersed aquatic plant species in Pools 4, 8, 13, and 26 of the Upper

Mississippi River and La Grange Pool of the Illinois River during spring and summer sampling, 1996.a

Pool Spring n Summer n

 4 1.7 ± 0.03 24 1.3 ± 0.04 18 b

 8 1.5 ± 0.01 95 1.0 ± 0.01 82 

13 1.5 ± 0.01 49 0.9 ± 0.01 56 

26 3.0 ± 0.05 4 – 0 

La Grange 2.6 ± 0.02 5 2.2 ± 0.10 9 c

Maximum rooting depth was calculated by averaging the deepest 10% of sites with submersed vegetation. a

Upper Mud Lake was excluded from calculations. b

Grape Island was excluded from calculations. c

Pool 4 

In 1996, more species were found in Pool 4 than in the other LTRMP study reaches and grew in water

up to 1.7 m deep (Tables 2 and 4); however, the overall frequency of vegetation was low in both the spring

(25%) and summer (19%) sampling periods (Table 5). Of the 11 submersed species found along transects

in Pool 4, 9 were recorded in the spring and 10 were recorded in the summer (Table 5). Shortspike

watermilfoil was found only during spring sampling, whereas flatstem pondweed (P. zosteriformis) and wild

celery were sampled only during the summer. Upstream of Lake Pepin, SAV was sparse and composed
13

singularly of sago pondweed; whereas, many more species were found in backwaters downstream of

Lake Pepin (Table 6). Lake Pepin is a 22-mile long tributary delta lake in the middle of Pool 4 that was

created by the Chippewa River depositing vast amounts of sand at its confluence with the Mississippi River.

Table 5. Frequencies and relative frequencies of submersed aquatic plant species found along transects in Pool 4 of

the Upper Mississippi River during spring (May 22–June 13) and summer (July 18–August 15) sampling periods, 1996.a

Frequencies (%) Relative frequencies (%)

Species n = 963 n = 950 Spring Summer 

Spring Summer 

coontail 4.4 2.9 11.7 8.2

(Ceratophyllum demersum)

pondweed, curly 8.6 1.3 24.6 4.0

(Potamogeton crispus)

pondweed, flatstem 0 0.1 0 0.3

(P. zosteriformis)

pondweeds, small and leafy 0.5 0.5 1.2 1.3

(P. pusillus, P. foliosus)

pondweed, longleaf 0.4 0.2 0.9 1.3

(P. nodosus)

pondweed, sago 14.3 4.8 54.3 17.4

(P. pectinatus)

water stargrass 0.2 1.1 0.5 2.6

(Heteranthera dubia)

watermilfoil, Eurasian 1.9 4.0 5.4 13.5

(Myriophyllum spicatum)

watermilfoil, shortspike 0.2 0 0.5 0

(M. sibiricum)

waterweed, Canadian 0.4 1.5 0.9 4.2

(Elodea canadensis)

wild celery 0 9.8 0 47.2

(Vallisneria americana)

Percent of vegetated sites 24.6 18.8 b

Upper Mud Lake sites were monitored during spring only and were excluded from analysis. a

From Table 3. b

Sago and curly pondweeds dominated the SAV community in spring (combined relative frequencies of

79%); however, they only grew in a small proportion of the sites sampled (14 and 9%, respectively; Table 5).

During summer sampling only one species, wild celery, exceeded a frequency of 5%. Wild celery (relative

frequency of 47%) replaced sago and curly pondweed as the dominant species. 

Seasonal differences were indicated for particular species and in the upper versus the lower pool

(Table 6). Sago pondweed was the only species found in the upper pool, where it declined significantly in

two backwaters. Robinson Lake (lower pool) was the most dynamic area, where both sago and curly

pondweeds decreased and three species (wild celery, water stargrass, and Canadian waterweed) increased.

Wild celery also expanded in Big Lake. Low frequency values limit the detection of trends in all but the most

commonly found species.
14

Table 6. Seasonality of submersed aquatic plant species sampled along transects in backwaters of Pool 4, Upper

Mississippi River, 1996.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between 

spring and summer spring and summer spring and summer

a a

coontail Big Lake

(Ceratophyllum demersum) Big Lake Bay

Lower Peterson Lake

Peterson Lake

Rice Lake

Robinson Lake

pondweed, curly Robinson Lake Big Lake

(Potamogeton crispus) Big Lake Bay

Lower Peterson Lake 

Peterson Lake

Rice Lake

pondweed, flatstem Robinson Lake

(P. zosteriformis)

pondweeds, small and leafy Big Lake Bay

(P. pusillus, P. foliosus) Robinson Lake

pondweed, longleaf Rice Lake

(P. nodosus) Robinson Lake

pondweed, sago Bay City Flats Big Lake

(P. pectinatus) Dead Slough Lake Big Lake Bay

b

b

Robinson Lake Goose Lakeb

Lower Peterson Lake

Mud Lakeb

Peterson Lake

Rice Lake

water stargrass Peterson Lake Robinson Lake

(Heteranthera dubia)

watermilfoil, Eurasian Big Lake

(Myriophyllum spicatum) Big Lake Bay

Lower Peterson Lake

Peterson Lake

Rice Lake

Robinson Lake 

watermilfoil, shortspike Rice Lake

(M. sibiricum)

waterweed, Canadian Peterson Lake Robinson Lake

(Elodea canadensis) 

wild celery Big Lake Bay Big Lake

(Vallisneria americana) Lower Peterson Lake Robinson Lake

Peterson Lake

Rice Lake

Changes in a species frequency were significant at P < 0.05. a

Upper Pool 4 locations. b

Pool 8

Of the 13 submersed species found along transects in Pool 8, 12 were recorded in the spring and 13 were

recorded in the summer, 1996 (Table 7). Wild celery was sampled only during the summer and at a very low

frequency (<1%). The areas where transects are located may not be suitable habitat for wild celery as it was
15

often observed in other areas of Pool 8 during the informal surveys. Water stargrass and horned pondweed

(Zannichellia palustris) were also rarely recorded. 

Coontail was the most frequently recorded species throughout the growing season (51% in spring and 52%

in summer) followed by sago pondweed (30%, both periods). Small and leafy pondweeds were the third most

common species in 1996. The small-leaved pondweed group, which would include sago and the small and

leafy pondweeds in Pool 8, comprised approximately 32% of the SAV community, nearing that of coontail

(43%) during both periods.

The percent of vegetated sites decreased between spring (73%) and summer (65%) sampling (Table 7).

Even though the frequency increased for all species except curly and sago pondweeds, there was still a

significant poolwide decline in vegetated areas. Overall, curly pondweed, which only declined by 7%,

decreased significantly in only two backwaters and actually increased in another (Table 8). This suggests that

most curly pondweed was found in Boomerang Island and Lawrence Lake and that following its senescence,

these sites were not vegetated by other species.

Table 7. Frequencies and relative frequencies of submersed aquatic plant species found along transects in Pool 8 of

the Upper Mississippi River during spring (May 20–June 13) and summer (July 15–August 12) sampling periods, 1996.

Frequencies (%) Relative frequencies (%)

Species n = 1,293 n = 1,252 Spring Summer 

Spring Summer 

bladderwort, common 2.0 2.5 0.9 1.2

(Utricularia macrorhiza)

coontail 50.7 52.2 43.7 43.4

(Ceratophyllum demersum)

pondweed, curly 17.0 10.0 9.6 4.8

(Potamogeton crispus)

pondweed, flatstem 3.6 4.4 2.1 2.2

(P. zosteriformis)

pondweeds, small and leafy 16.2 19.3 13.0 14.0

(P. pusillus, P. foliosus )

pondweed, longleaf 0.7 1.6 0.4 0.9

(P. nodosus)

pondweed, sago 29.6 29.6 20.4 17.9

(P. pectinatus)

pondweed, horned 0.2 0.2 0.1 0.1

(Zannichellia palustris)

water stargrass 0.1 0.7 <0.1 0.3

(Heteranthera dubia)

watermilfoil, Eurasian 11.8 15.1 7.9 9.5

(Myriophyllum spicatum)

waternymph, nodding 0.1 4.8 0.1 3.0

(Najas flexilis)

waterweed, Canadian 2.8 4.0 1.8 2.5

(Elodea canadensis)

wild celery 0 0.3 0 0.2

(Vallisneria americana)

Percent of vegetated sites 73.4 65.4 a

From Table 3. a
16

Only sago and curly pondweeds declined in any discrete locations (Table 8). In contrast, common

bladderwort (Utricularia macrorhiza), coontail, small and leafy pondweeds, Eurasian watermilfoil, and

nodding waternymph increased in at least one location. Lawrence and Blue Lakes were the most seasonally

dynamic areas, and all 13 species recorded in Pool 8 were found in Lawrence Lake.

Table 8. Seasonality of submersed aquatic plant species sampled along transects in backwaters of Pool 8 of the Upper

Mississippi River, 1996.

Species sampling period sampling period sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a a

bladderwort, common Lawrence Lake Blue Lake

(Utricularia macrorhiza) Target Lake

coontail Goose Island Blue Lake

(Ceratophyllum demersum) Lawrence Lake

Shady Maple

Stoddard, Wisconsin 

Target Lake

pondweed, curly Boomerang Island Goose Island Blue Lake

(Potamogeton crispus) Lawrence Lake Horseshoe Island

Shady Maple

Stoddard, Wisconsin

Target Lake

pondweed, flatstem Blue Lake

(P. zosteriformis) Goose Island

Lawrence Lake

Target Lake

pondweeds, small and leafy Blue Lake Goose Island

(P. pusillus, P. foliosus) Boomerang Island Lawrence Lake

Horseshoe Island

Stoddard, Wisconsin

Target Lake

pondweed, longleaf Goose Island

(P. nodosus) Lawrence Lake

Shady Maple

Target Lake

pondweed, sago Boomerang Island Blue Lake Target Lake

(P. pectinatus) Goose Island Lawrence Lake

Horseshoe Island Shady Maple

Stoddard, Wisconsin 

pondweed, horned Goose Island

(Zannichellia palustris) Horseshoe Island

Lawrence Lake

water stargrass Goose Island

(Heteranthera dubia) Lawrence Lake

Target Lake

watermilfoil, Eurasian Goose Island Lawrence Lake

(Myriophyllum spicatum) Shady Maple

Target Lake

waternymph, nodding Target Lake Blue Lake

(Najas flexilis) Lawrence Lake
Table 8. Continued.

Species sampling period sampling period sampling periods

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a a

17

waterweed, Canadian Blue Lake

(Elodea canadensis) Goose Island

Horseshoe Island

Lawrence Lake

Stoddard, Wisconsin

Target Lake

wild celery Boomerang Island

(Vallisneria americana) Lawrence Lake

Changes in a species frequency were significant at P < 0.05. a

Pool 13

Of the 13 submersed species found along transects in Pool 13 in 1996, 10 were found during the spring

sampling period and 13 during the summer sampling period (Table 9). Chara, nodding waternymph, and southern

waternymph were found only during the summer sampling.

The percent of sites with SAV increased in Pool 13 from spring (49%) to summer (56%). Sago pondweed

was the most abundant species found during both sampling periods (40% and 32% in the spring and summer,

respectively). In the spring, sago pondweed and coontail together comprised 77% of the SAV community.

Despite an increase in coontail, their combined relative frequencies dropped to only 50% by late summer,

because other species expanded. The frequencies of wild celery and water stargrass increased by >10%

between sampling periods causing them to become the third most important species in Pool 13 by the summer

(relative frequencies of 18%). Chara and small and leafy pondweeds were rarely recorded (<1%).

Table 9. Frequencies and relative frequencies of submersed aquatic plant species found along transects in Pool 13 of

the Upper Mississippi River during spring (May 21–June 19) and summer (July 19–August 21) sampling period, 1996.

Frequencies (%) Relative frequencies (%)

Species n = 985 n = 996 Spring Summer 

Spring Summer 

chara 0 0.2 0 0.1

(Chara spp.)

coontail 11.4 20.2 13.6 18.8

(Ceratophyllum demersum)

pondweed, curly 1.2 1.7 0.9 0.9

(Potamogeton crispus)

pondweed, flatstem 0.2 1.1 0.2 0.6

(P. zosteriformis)

pondweeds, small and leafy 0.1 0.4 0.1 0.3

(P. pusillus, P. foliosus)

pondweed, longleaf 1.5 2.2 2.0 1.5

(P. nodosus)

pondweed, sago 40.0 32.1 63.6 31.3

(P. pectinatus)

water stargrass 6.8 20.2 7.1 17.9

(Heteranthera dubia)
Table 9. Continued.

Frequencies (%) Relative frequencies (%)

Species n = 985 n = 996 Spring Summer 

Spring Summer 

18

watermilfoil, Eurasian 1.2 5.5 1.3 3.7

(Myriophyllum spicatum)

waternymph, nodding 0 1.7 0 1.5

(Najas flexilis)

waternymph, southern 0 2.2 0 2.0

(N. guadalupensis)

waterweed, Canadian 2.8 3.9 3.7 3.6

(Elodea canadensis)

wild celery 6.4 16.4 7.5 17.7

(Vallisneria americana)

Percent of vegetated 49.1 56.2

sitesa

From Table 3. a

Only sago pondweed declined between sampling periods in Pool 13 (Table 10). In comparison, five

species increased in at least one location. Of these, water stargrass, Eurasian watermilfoil, and wild celery

expanded in most of the backwaters where they were found. Johnson Creek, where five species increased,

was the most dynamic area in Pool 13. In addition, all 13 species found in 1996 were recorded in Johnson

Creek.

Table 10. Seasonality of submersed aquatic plant species sampled along transects in backwaters of Pool 13 of the

Upper Mississippi River, 1996.

Species sampling period sampling period sampling period

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a a

chara Johnson Creek

(Chara spp.)

coontail Johnson Creek Levee Brown’s Lake

(Ceratophyllum demersum) Pomme de Terre Johnson Creek

Savanna Bay

Spring Lake

pondweed, curly Brown’s Lake

(Potamogeton crispus) Johnson Creek 

Johnson Creek Levee

Potter’s Marsh

Savanna Bay

Spring Lake

pondweed, flatstem Johnson Creek

(P. zosteriformis) Johnson Creek Levee

Savannah Bay

pondweeds, small and leafy Brown’s Lake

(P. pusillus, P. foliosus) Johnson Creek

Spring Lake
Table 10. Continued.

Species sampling period sampling period sampling period

Decreased between No change between Increased between

spring and summer spring and summer spring and summer

a a

19

pondweed, longleaf Brown’s Lake 

(P. nodosus) Johnson Creek

Johnson Creek Levee

Pomme de Terre

Potter’s Marsh

Savanna Bay

Spring Lake

pondweed, sago Brown’s Lake Johnson Creek

(P. pectinatus) Johnson Creek Levee Pomme de Terre

Potter’s Marsh Savanna Bay

Spring Lake

water stargrass Savanna Bay Johnson Creek

(Heteranthera dubia) Spring Lake Johnson Creek Levee

Pomme de Terre

Potter’s Marsh

watermilfoil, Eurasian Spring Lake Johnson Creek

(Myriophyllum spicatum) Potter’s Marsh Johnson Creek Levee

Pomme de Terre

waternymph, nodding Johnson Creek

(Najas flexilis) Johnson Creek Levee

Savanna Bay

Spring Lake

waternymph, southern Brown’s Lake Johnson Creek

(N. guadalupensis) Johnson Creek Levee

Pomme de Terre

Spring Lake

waterweed, Canadian Johnson Creek

(Elodea canadensis) Johnson Creek Levee

Pomme de Terre

wild celery Potter’s Marsh Johnson Creek

(Vallisneria americana) Spring Lake Johnson Creek Levee

Pomme de Terre

Changes in a species frequency were significant at P < 0.05. a

Pool 26

Overall, in Pool 26 vegetation was sparse and found only during spring sampling in Stump Lake in 1996

(12%; Tables 11 and 12). Sago and longleaf pondweeds were the only species recorded. Whereas both

species disappeared between sampling periods, the low frequency of longleaf pondweed precluded

significance. Swan Lake, a backwater sampled in previous years, was not sampled in 1996 because of

construction of a HREP. The lack of vegetation in this river reach was possibly influenced by the second

consecutive year of spring flooding by the Illinois River, shown by the elevated river stage and rooting depths

exceeding 3 m (Figure 7; Table 4). It is also likely that the lack of vegetation is related to record flooding in

1993. Since that time, SAV has been absent from most of the backwaters of the lower Illinois River. This

question has not been formally addressed in this study, but the data presented in Figure 7 and observations

made during the monitoring and analysis phases of this study suggest a possible correlation between water

depth and vegetation abundance. 
20

Table 11. Frequencies and relative frequencies of submersed aquatic plant species found along transects in Pool 26

of the Upper Mississippi River during spring (June 5–13) and summer (August 2–8) sampling periods, 1996.

Frequencies (%) Relative frequencies (%)

Species n = 310 n = 166 Spring Summer 

Spring Summer 

pondweed, longleaf 1.3 0 10.0 0

(Potamogeton nodosus)

pondweed, sago 11.6 0 90.0 0

(P. pectinatus)

Percent of vegetated sites 12.3 0

a

From Table 3. a

Table 12. Seasonality of submersed aquatic plant species sampled along transects in backwaters of Pool 26 of the

Upper Mississippi River, 1996.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between 

spring and summer spring and summer spring and summer

a a

pondweed, longleaf Stump Lake

(P. nodosus)

pondweed, sago Stump Lake

(P. pectinatus)

Changes in a species frequency were significant at P < 0.05. a

La Grange Pool

Ten submersed species were found along transects in La Grange Pool in 1996 (Table 13). Of these, 6 were

recorded during spring sampling and 10 during summer sampling. Chara, horned pondweed, nodding

waternymph, and Canadian waterweed were found only in the summer. 

More than half of the sites were vegetated with SAV throughout the growing season (Table 13). Eurasian

watermilfoil was more abundant than any other species during both sampling periods (frequencies of 38 and

67%). In the spring, Eurasian watermilfoil combined with coontail to account for >75% of the community.

Coontail’s frequency was comparable throughout the growing season (16 and 18%), however, its relative

importance decreased from 31 to 11% because small and leafy pondweeds expanded later in the season. 

Table 13. Frequencies and relative frequencies of submersed aquatic plant species found along transects in La Grange

Pool of the Illinois River during spring (May 22–30) and summer (July 17–August 1) sampling periods, 1996.a

 Frequencies (%) Relative frequencies (%)

Species n = 89 n = 117 Spring Summer 

Spring Summer 

chara 0 10.3 0 5.2

(Chara spp.)

coontail 15.7 17.9 30.9 11.2

(Ceratophyllum demersum)

pondweed, curly 12.4 18.8 11.3 9.7

(Potamogeton crispus)
Table 13. Continued.

 Frequencies (%) Relative frequencies (%)

Species n = 89 n = 117 Spring Summer 

Spring Summer 

21

pondweeds, small and leafy 3.4 20.5 3.1 13.3

(P. pusillus, P. foliosus)

pondweed, longleaf 2.2 6.0 2.1 4.4

(P. nodosus)

pondweed, sago 6.7 6.8 6.2 2.3

(P. pectinatus)

pondweed, horned 0 8.5 0 4.2

(Zannichellia palustris)

watermilfoil, Eurasian 38.2 66.7 46.4 46.1

(Myriophyllum spicatum)

waternymph, nodding 0 2.6 0 1.0

(Najas flexilis)

waterweed, Canadian 0 3.4 0 2.6

(Elodea canadensis)

Percent of vegetated 52.8 72.7

sitesb

Grape Island sites were monitored during summer only and were excluded from analysis. a

From Table 3. b

All 10 of the species recorded in La Grange Pool were found in Spring Lake. In addition, seasonal changes

were significant only in Spring Lake, where curly pondweed, small and leafy pondweeds, and Eurasian

watermilfoil increased (Table 14). Eurasian watermilfoil rebounded from its collapse in Spring Lake in 1995,

and the species that appeared during Eurasian watermilfoil’s nadir were sustained in 1996.

Coontail was the only species found in Point Lake, one of two backwaters with transects that are

contiguous with the main stem of the Illinois River. The other backwater, Grape Island (sampled only in the

summer due to high water in the spring), was devoid of vegetation. Unusually high water levels in the spring

and again in mid-summer may explain the scarcity of plants in areas contiguous with the Illinois River.

Elevated water levels would be less likely to affect Spring Lake and Banner Marsh because they are isolated

from all but the highest river stages.

Table 14. Seasonality of submersed aquatic plant species sampled along transects in backwaters of La Grange Pool

of the Illinois River, 1996.

Species sampling periods sampling periods sampling periods

Decreased between No change between Increased between 

spring and summer spring and summer spring and summer

a a

chara Spring Lake

(Chara spp.)

coontail Banner Marsh

(Ceratophyllum demersum) Point Lake

Spring Lake

pondweed, curly Banner Marsh Spring Lake

(Potamogeton crispus)

pondweeds, small and leafy Banner Marsh Spring Lake

(P. pusillus, P. foliosus)
Table 14. 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 a

22

pondweed, longleaf Banner Marsh

(P. nodosus) Spring Lake

pondweed, sago Banner Marsh

(P. pectinatus) Spring Lake

pondweed, horned Spring Lake

(Zannichellia palustris)

watermilfoil, Eurasian Banner Marsh Spring Lake

(Myriophyllum spicatum)

waternymph, nodding Spring Lake

(Najas flexilis)

waterweed, Canadian Spring Lake

(Elodea canadensis)

Changes in a species frequency were significant at P < 0.05. a

Acknowledgments

The authors gratefully acknowledge M. Coulombe-Moore, K. Hanson, K. McKeever, J. Mootz,

N. Olenych, W. Popp, S. Skemp, and S. Stratton and for their valuable assistance and support. We also thank

LTRMP field station staff and the participating agencies: Illinois Natural History Survey, Alton and La

Grange; Iowa Department of Natural Resources, Bellevue; Minnesota Department of Natural Resources,

Lake City; and Wisconsin Department of Natural Resources, Onalaska.

References

Barko, J. W., and R. M. Smart. 1981. Comparative influences of light and temperature on the growth and

metabolism of selected submersed freshwater macrophytes. Ecological Monographs 51(2):219–235. 

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. 22 pp.

Fassett, N. C. 1957. A manual of aquatic plants. University of Wisconsin Press, Madison. 405 pp.

Flint, N. A., and J. D. Madsen. 1995. The effect of temperature and daylength on the germination of

Potamogeton nodosus tubers. Journal of Freshwater Ecology 10(2):125–128.

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.

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.
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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

of Minnesota Press, Minneapolis.

Madsen,J. D., and M. S. Adams. 1988. The germination of Potamogeton pectinatus tubers: Environmental

control by temperature and light. Canadian Journal of Botany 66:2523–2526.

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)

Voss, E. G. 1972. Michigan flora, Part I, gymnosperms and monocots. Cranbrook Institute of Science,

Bloomfield Hills, Michigan. 488 pp.

Voss, E. G. 1985. Michigan flora, Part II, dicots. Regents of the University of Michigan, Ann Arbor. 724 pp.
A-1

Appendix A

Locations, Habitat, 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 1996 Sampling Season

Location transects sites sites sampled sampled between 

(river mile) Habitat spring:summer spring summer spring summer sites (m) a

Number of Number of Number of Dates Dates Distance 

Pool 4

Upper Mud Lake BWC 4:0 41 Not sampled 6/13 Not 30

(M791.5) sampled b

Mud Lake BWC 3:3 63 55 6/12 8/13, 15 30

(M791.3)

Dead Slough Lake BWC 9:9 136 136 6/11–12 8/8–9, 13 30

(M789.2, M788.5,

 M788.0)

Goose Lake BWC 3:3 30 28 6/10 8/8 30

(M788.G)c

Catherine Pass BWC 3:3 80 85 6/10 8/7 30

(Bay City Flats;

 M787.0)d

Robinson Lake BWC 9:9 228 225 5/24, 29–31; 7/24–26, 30

(M758.R) 6/4 29–30 c

Big Lake Bay BWC 3:3 46 45 6/5 8/5–6, 14 30

(M758.5)

Rice Lake BWC 3:3 39 35 6/7 7/30–31 30

(M758.0)

Big Lake BWC 5:5 182 160 6/5–7 7/31–8/2, 30

(M757.5) 8/6

Peterson Lake BWC 6:6 55 53 5/22 7/18–19 30

(M754.8, M754.5)

Lower Peterson Lake BWC 4:4 104 128 5/23 7/22–24 30

(M753.5)

Total Pool 4 52:48 1,004 950 14 20

Pool 8

Blue Lake BWI 3:3 126 118 6/4–5 7/24–25 15

(M697.0)

Target Lake BWC 11:11 293 279 5/20–24 7/15–18 15

(M696.0)

Goose Island BWC 5:5 112 114 5/31; 6/3 7/29 15

(M692.0)

Lawrence Lake BWC 10:10 421 417 6/7, 10–13 7/31–8/2, 15

(M691.0) 6–9, 12

Shady Maple BWC 3:3 102 90 6/3 7/26 15

(M690.0)
Location transects sites sites sampled sampled between 

(river mile) Habitat spring:summer spring summer spring summer sites (m) a

Number of Number of Number of Dates Dates Distance 

A-2

Horseshoe Island BWC 5:5 85 82 6/6 7/30 15

(Pool 8 Islands

 HREP; M687.0)e

Boomerang Island IMP 4:4 104 104 5/28–29 7/19 15

(Pool 8 Islands

 HREP; M686.0)e

Stoddard, Wisconsin BWI 4:4 50 48 5/30 7/23 15

(M684.0)

Total Pool 8 45:45 1,293 1,252 18 19

Pool 13

Brown's Lake BWC 15:15 338 357 6/5–6, 11–14 8/1–2, 5, 15

(M545.1, M544.5) 7–9, 12–13,

Savanna Bay BWC 12:12 142 139 5/29–30 7/26, 29 15

(M541.5, M540.5,

 M539.5)

Spring Lake BWC 10:12 162 166 5/31; 6/3–4 7/30–31 15

(M534.8, M533.6,

 M532.0 )

Pomme de Terre IMP 5:5 75 75 5/21 7/19, 22 15

(M526.0)

Potter's Marsh IMP 6:6 96 92 6/17 8/14–16 15

(M524.0)

Johnson Creek Levee IMP 4:4 113 102 6/18–19 8/20–21 15

(M523.5)

Johnson Creek IMP 2:2 59 65 5/22, 29 7/23–25 15

(M523.0)

Total Pool 13 54:56 985 996 16 22

Pool 26

Calhoun Point BWI 18:3 156 27 6/13 8/8 15

(I003.0)f

Stump Lake BWI 7:4 125 102 6/11–12 8/8 15

(I010.0)

Fuller Lake BWI 2:2 29 37 6/5, 12 8/2 15

(I011.5)

Total Pool 26 27:9 310 166 4 2

La Grange Pool

Grape Island SC 0:3 Not sampled 12 Not sampled 8/1 15

(I086.4)

Point Lake BWI 6:6 22 22 5/30 7/29 15

(I100.0)

Spring Lake IMP 5:5 51 78 5/24, 27, 30 7/18, 22, 15

(I135.5) 24–25
Location transects sites sites sampled sampled between 

(river mile) Habitat spring:summer spring summer spring summer sites (m) a

Number of Number of Number of Dates Dates Distance 

A-3

Banner Marsh IMP 2:2 16 17 5/22–23 7/17 15

(Bulrush Pond;

 I140.7)d

Total La Grange Pool 13:16 89 129 5 7

Type of habitats: BWC = Backwater contiguous, BWI = Backwater isolated, IMP = Impounded, SC = Side channel. 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

Locally recognized alternate name. d

Part of the Pool 8 Islands Habitat Rehabilitation and Enhancement Project. e

Illinois River miles, measured from the confluence of the Mississippi and Illinois Rivers. Pool 26 is located at the confluence f

of the Mississippi and Illinois Rivers and the portions named here extend up the Illinois River, are managed by the Illinois

Department of Natural Resources, and are designated by Illinois River miles.
B-1

Appendix B

List of Submersed and Floating-leaved Aquatic Species Present at Transect Sites in

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

River During Monitoring for the Long Term Resource Monitoring Program, 1991–1996a

Family Scientific name Common name

Azollaceae (Salviniaceae) Azolla spp. watervelvet, mosquitofern b

Ceratophyllaceae Ceratophyllum demersum L. coon’s tail, coontail

Characeae Chara spp. chara

Characeae Nitella spp. nitella

Haloragaceae Myriophyllum sibiricum Komarov northern watermilfoil,

shortspike watermilfoil

Haloragaceae Myriophyllum spicatum L. Eurasian watermilfoil,

spike watermilfoil 

Hydrocharitaceae Elodea canadensis Michx. Canadian waterweed

Hydrocharitaceae Vallisneria americana Michx. wild celery, American eelgrass

Lemnaceae Lemna minor L. lesser duckweed, small duckweed b

common duckweed

Lemnaceae Lemna trisulca L. star duckweed b

Lemnaceae Spirodela polyrhiza (L.) Schleid. greater duckweed, big duckweed, b

common duckweed

Lemnaceae Wolffia braziliensis Weddell Brazilian watermeal b

(Wolffia papulifera C. Thompson

Wolffia punctata Griseb.)

Lemnaceae Wolffia columbiana Karst. Columbian watermeal b

Lentibulariaceae Utricularia macrorhiza Le Conte common bladderwort

(Utricularia vulgaris L.)

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

nodding waternymph

Najadaceae Najas gracillima (A. Braun ex Engelm.) Magnus slender waternymph 

Najadaceae Najas guadalupensis (Spreng.) Magnus southern waternymph c

Nymphaeaceae Nelumbo lutea Willd. American lotus

Nymphaeaceae Nuphar lutea (L.) Sm yellow pondlily

Nymphaeaceae Nymphaea odorata Ait. American white waterlily

Onagraceae Ludwigia decurrens Walt. b wingleaf primrosewillow

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

(Zosterella dubia [Jacq.] Small ) grassleaf mudplantain

Potamogetonaceae Potamogeton alpinus Balbis red pondweed, alpine pondweed d

Potamogetonaceae Potamogeton crispus L. curly pondweed, 

curlyleaf pondweed

Potamogetonaceae Potamogeton epihydrus Raf. ribbonleaf pondweed

Potamogetonaceae Potamogeton foliosus Raf. leafy pondweed

Potamogetonaceae Potamogeton gramineus L. variableleaf pondweed

Potamogetonaceae Potamogeton illinoensis Morong. Illinois pondweed d

Potamogetonaceae Potamogeton natans L. floating pondweed d

Potamogetonaceae Potamogeton nodosus Poir river pondweed, American

pondweed, longleaf pondweed

Potamogetonaceae Potamogeton pectinatus L sago pondweed
Family Scientific name Common name

B-2

Potamogetonaceae Potamogeton pusillus L. small pondweed, slender

pondweed

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

Potamogetonaceae Potamogeton zosteriformis Fern. flatstem pondweed

Ranunculaceae Ranunculus flabellaris Raf. yellow water buttercup

Ranunculaceae Ranunculus longirostris Godr. longbeak buttercup, white water e

crowfoot

Zannichelliaceae Zannichellia palustris L. horned pondweed

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

(http://plants.usda.gov/plants/). Common names most often used by Upper Mississippi River managers are also included.

Species excluded from analysis. b

Verified for Pool 13 by Dr. E. Cawley, Loras College, Iowa. c

Verified by Dr. C. B. Hellquist, North Adams State College, Massachusetts. d

Ranunculus longirostris and R. trichophyllus were combined (Voss 1985). e
REPORT DOCUMENTATION PAGE Form Approved

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

November 1998

4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

1996 annual status report: A summary of aquatic vegetation monitoring at fixed transects in Pools 4, 8, 13, and 26 and La

Grange Pool of the Upper Mississippi River System

6. AUTHOR(S)

Sara Rogers , Heidi Langrehr , J. Therese Dukerschein , Jenny Winkelman , John Nelson , Theresa Blackburn , and Thad 1 2 2 3 4 5

Cook6

7. PERFORMING ORGANIZATION NAME AND ADDRESS 8. PERFORMING ORGANIZATION

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

Wisconsin Department of Natural Resources, Onalaska Field Station, 575 Lester Avenue, Onalaska, Wisconsin 54650. 2

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

Illinois Natural History Survey, Alton Field Station, 4134 Alby Street, Alton, Illinois 62002. 4

Iowa Department of Natural Resources, Mississippi River Monitoring Station, 206 Rose Street, Bellevue, Iowa 52031. 5

Illinois Natural History Survey, Havana Field Station, 704 North Schrader Avenue, Havana, Illinois 62644. 6

 REPORT NUMBER

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

U.S. Geological Survey 

Environmental Management Technical Center 98-P012

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)

Distribution and frequency of submersed aquatic vegetation in the Upper Mississippi River System are monitored as part of the Long Term Resource Monitoring

Program. This report summarizes results of sampling aquatic vegetation along fixed transects in Navigation Pools 4, 8, 13, and 26 in the Upper Mississippi River and La

Grange Pool in the Illinois River in 1996. Plants were sampled at regular intervals along fixed transects using a modified rake technique. Sampling was conducted twice

during the growing season (spring and summer). Twenty-four submersed and rooted floating-leaved species were found. Most species were found in Pools 4, 8, and 13.

Pool 26 had the fewest (3) number of species and Pool 4 had the greatest (23), including most large-leaved pondweeds and the first LTRMP record of floating pondweed

(Potamogeton natans). Sago pondweed (P. pectinatus) and coontail (Ceratophyllum demersum) were dominant in the contiguous backwaters sampled. Seasonal trends

were observed in 10 species, all of which increased later in the season. Throughout the growing season, more sites were vegetated in Pools 8 and 13 and La Grange

Pool (frequency of 50–73%) than in Pools 4 and 26 (<25%). Pool 26 was devoid of vegetation during the second sampling. Aquatic vegetation was generally rare in

contiguous areas of Pool 26 and La Grange Pool, but more plentiful in the isolated, managed backwaters of La Grange Pool.

14. SUBJECT TERMS 15. NUMBER OF PAGES

1996 annual report, aquatic plant monitoring, Illinois River, La Grange Pool, LTRMP, Mississippi River, submersed 23 pp. + Appendixes A–B

aquatic vegetation

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.