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Des Plaines River, IL - The Des Plains River 

Wetlands Project: Wetlands for River Water Quality 

Improvement

System Description

Hydrology

System Performance

Water Quality Responses

Vegetation Responses

Wildlife Use

Acknowledgements

Research Groups
System Description

Wetlands EW3 and EW4 are encircled by access roads, 

and bordered by US Highway 41 (bottom) and 

Wadsworth Road (left). Flow enters EW3 from the left, 

and enters EW4 from the bottom. Both discharge to a 

swale (top right), which is connected to the Des Plaines 

River. On this aerial infrared photo, water is black and 

cattails are dark red.

The Des Plaines River Wetlands Demonstration 

Project is designed to produce the criteria necessary 

for rebuilding our river systems through the use of 

wetlands and for developing management programs 

for the continued operation of the new structures. 

The research program is assessing wetland 

functions through large-scale experimentation, 

controlled manipulation of flow rates and water 

depths, testing of soil conditions, and the 

employment of a wide variety of native plant 

communities. 

Four wetlands have been constructed near 

Wadsworth, Illinois, for purposes of river water 

quality improvement. The river drains an 

agricultural and urban watershed, and carries a nonpoint source contaminant load of sediment, 

nutrients and agricultural chemicals. The site is 

located 35 miles north of Chicago. It incorporates 

2.8 miles of the upper Des Plaines River and 450 

acres of riparian land. The river flows south, 

draining 200 square miles in southern Wisconsin 

and northeastern Illinois. Eighty percent of the 

watershed is agricultural and 20 percent urban. The 

river is polluted with non-point source contaminants 

from a variety of land use activities, and point source contaminants from small domestic treatment plants. 

In support of previous agricultural uses, low-lying portions of the site were drained by means of tiles. 

Past uses of the site included pasture and a Christmas tree farm which resulted in the demise of most of 

the original wetlands and associated fauna and flora. 

Water is pumped from the river to the wetlands, from a point just south of Wadsworth Road. This energy 

intensive alternative was necessary because of site constraints, and because of the desire to explore a 

wide range of hydraulic conditions. Gravity diversion would be a preferred alternative in most 

applications of this technology. Water leaving the wetlands returns to the river via grassy swales. 
Hydrology

The river is a "good old muddy midwestern stream." Shown here at 

average flow, it regularly floods a large amount of bottom land. In the 

summer of 1988, a severe drought caused it to dry to a disconnected 

string of pools.

The Des Plaines River enters the site from the north, passing 

under the Wadsworth Road bridge. It is relatively wide and 

shallow under normal flow conditions—100 feet wide and 

about 2 feet deep. This reach exhibits channel stability, 

primarily because of the low energy state of the river. Stream 

velocities average less than 1 foot per second. The gradient is 

1.2 feet per mile. 

About 15% of the variable stream flow is pumped to the 

wetlands, and allowed to return from the wetlands to the river 

through control structures followed by vegetated channels. 

Native wetland plants have been established, ranging from 

cattail, bulrushes, water lilies, and arrowhead to duckweed and 

algae. Pumping began in the 1989, and has continued during 

the ensuing spring, summer and fall periods. The experimental 

design provides for different hydraulic loading rates, ranging 

from 2 to 24 inches per week. Intensive wetland research began in late summer 1989, and continues to 

present. 

The hydrology of the wetland complex has been studied extensively. Groundwater investigations showed 

a relatively complex local flow pattern, with some groundwater interactions with the river. Wetland EW5 

leaks to groundwater, as does wetland EW5 to a minor extent. For WY 1990 (October 1989-September 

1990), precipitation and evapotranspiration were equal. 
Pumping creates a fountain effect at the inlet to each 

wetland.

Pumping occurred for all weeks in 1990, but was 

discontinued in winter in subsequent years. The pump 

is run on weekdays, for a prescheduled period. In WY 

1990, it was run 10.5% of the time. Outflow from the 

wetlands is controlled by weirs. Thus the hydrologic 

regime is cyclic, with increasing water levels and flows 

during the few daily hours of pumping, followed by a 

lowering of water levels and a slowing of flows during 

the off hours. 

Annual Average Water budget Compnents,

WY1990 (cm/day)

. EW3 EW4 EW5 EW6

Inflows

Surface Inflow 5.36 1.46 5.01 2.78
Precipitation 0.26 0.26 0.26 0.26

Outflows

Discharge 5.36 1.46 4.80 0.35

Evapotranspiration 0.26 0.26 0.26 0.26

Seepage 0.00 0.00 0.21 2.43

River enters the site from the north, passing under the Wadsworth Road 

bridge. It is relatively wide and shallow under normal flow conditions 100 

feet wide and about 2 feet deep. This reach exhibits channel stability, 

primarily because of the low energy state of the river. Stream velocities 

average less than 1 foot per second. The gradient is 1.2 feet per mile.
System Performance

The wetland internal flow patterns are not ideal in any 

sense of the word. The nominal detention times in the 

wetlands range from one to three weeks under moderate 

to high flow conditions. Some of the pumped water 

moves quickly toward the outlet, and reaches it in about 

one days time. Other portions of the pumped water are 

trapped in the litter and floc near the wetland bottom. Still 

other portions are slowed by plant clumps, or blown off 

course by the wind. The net effect is that some water 

takes three times as long as the average to find its way out 

of the wetland. 

Tracer studies have been run at Des Plaines, using lithium 

chloride as the tracer material. A sudden dump of 

dissolved lithium is made into the wetland inflow. The 

outflow is then analyzed for the lithium, which appears at 

varying concentrations and at various times after the 

dump. These tests have established that the degree of mixing within the wetlands is higher than expected. But surprisingly, 

there is not a great deal of difference between wetlands, even though they differ in shape.

Suspended Solids In and Out of 

the Des Plaines Wetlands (mg/l)

. Inlet EW3 EW4 EW5 EW6

FA89 8.0 2.0 2.4 2.6 3.0

WI89 7.1 5.0 3.6 4.2 3.0

SP90 24.2 5.5 4.5 2.9 3.3

SU90 47.7 5.7 14.9 4.3 13.9

FA90 50.1 10.8 7.4 5.4 4.4

SP91 63.9 5.8 7.4 2.4 6.2

SU91 123 6.0 6.8 3.2 7.8

FA91 66.0 10.8 6.7 25.8 NF

AVG 48.8 6.5 6.7 4.9 6.1

% Removal 87% 86% 90% 87%

The primary water quality problem of the river is associated with 

turbidity. With a mean concentration of 59 parts per million, over 5,000 

tons of suspended solids enter the site per year via the Des Plaines River 

and Mill Creek. Seventy-five percent of these solids are inorganic and 

95 percent are less than 63 microns in size. Sediment removal 

efficiencies ranged from 86-100% for the four cells during summer, and 

from 38-95% during winter. 

A fish story developed in 1990. The solids in the 

wetland effluents were steadily increasing with each 

passing week. The source of the problem was found: 

a large number of carp were growing up in the wetlands. These fish foraged in the wetland sediments, causing resuspension of 

solids. They entered as fry in the pumped water, and grew to 8-10 inches over the first two years of the project. The solution 

was to draw down the wetland water levels, in winter 1990-91, and freeze out the carp. Solids removal returned to the 

previous high levels of efficiency.
Carp rooted up sediments and impaired sediment 

removal efficiency. They were frozen out and 

removed.
Water Quality Responses

Suspended Solids In and Out of 

the Des Plaines Wetlands (mg/l)

. Inlet EW3 EW4 EW5 EW6

FA89 0.052 0.018 0.013 0.014 0.018

WI89 0.073 0.053 0.030 0.058 0.024

SP90 0.057 0.044 0.015 0.017 0.023

Other observed river water quality problems 

included violations of the state water quality 

standards for iron, copper, and fecal coliforms. 

These pollutants are found only occasionally, and 

not in dangerously high concentrations. Although 

not detected in amounts exceeding the federal Food 

and Drug Administration's criteria, dieldrin, DDT 

and PCBs have been found in fish flesh samples. 

DDT, DDE and PCBs were also found in low 

concentrations in the river borne sediments. The 
SU90 0.117 0.038 0.055 0.035 0.062

FA90 0.131 0.024 0.007 0.017 0.011

SP91 0.089 0.003 0.002 0.001 0.002

SU91 0.119 0.010 0.010 0.010 0.009

AVG 0.091 0.027 0.019 0.022 0.021

% Removal 65% 78% 73% 75%

old pesticides are pervasive everywhere else in the 

environment, and so will be in these wetlands. The 

river bears a significant nutrient load, as evidenced 

by nitrate and phosphorus. These fertilizers peak 

seasonally, corresponding to runoff timing and 

land use practices within the watershed. 

Agricultural practices within the basin produce 

pollution with atrazine, at concentrations which 

peak in excess of the federal drinking water standard. According to the results of benthic surveys, the 

stream is classified as semi-polluted. 

Phosphorus removal efficiencies average 65–80%. However, efficiency is lower in winter and higher in 

summer. That is partly because the riverine concentrations of phosphorus are very low in winter, and 

partly because biological processes slow in the cold temperatures. Winter runoff in the watershed is 

overland, over frozen soils or ice and snow. The result is low phosphorus in the river in winter. 

Most phosphorus enters the wetlands associated with mineral suspended solids. These solids settle 

quickly, and may not freely exchange their phosphorus with the wetland waters. In addition, there is a 

large biotic cycle of growth, death and decomposition at work, which leaves a residual of organic 

sedimentary material. The deposition from this cycle exceeds the deposition of incoming river solids by a 

wide margin. Both processes immobilize phosphorus in these wetlands. During the early years, 

phosphorus is also tied up in the new biomass associated with these developing ecosystems. 

Nitrate Nitrogen Reduction, (mg/l)

. Inlet EW3 EW4 EW5 EW6

FA89 2.46 1.46 0.04 1.27 0.08

WI89 2.15 0.67 0.17 1.51 0.25

1990 1.87 0.54 0.24 0.53 0.32

1991 1.22 0.23 0.10 0.18 0.18

AVG 1.80 0.61 0.15 0.70 0.22

AVG % 66% 92% 61% 88%

There are a variety of nitrogen forms in the river 

water. About 0.6 mg/l of organic nitrogen enter the 

wetlands, and the same amount leaves. Very low 

ammonium nitrogen concentrations are found in 

both river and wetland waters: about 0.05 mg/l. 

Nitrate varies seasonally in the river, in response to 

urban and agricultural practices. High spring and 

fall concentrations are echoed by similar variations 

in the nitrate content of the wetland effluent 

waters. However, in the warm seasons, a 

considerable amount of the incoming nitrate is 

removed, presumably due to denitrification. This 

microbially mediated process appears to be more 

efficient in the wetlands with lower hydraulic 

loading rate, which is equivalent to increased detention time since depths are comparable. Thus the 

overall effect of the wetlands is to control the nitrate in the water when sufficient contact time is 

available. 

Atrazine, a triazine herbicide, exists in many streams in the upper midwestern part of the United States, 

including the Des Plaines River, due to use patterns in the watershed. The atrazine-wetland interaction is 
very complex, including removal from the area by convection in the water, loss of chemical identity by 

hydrolysis to hydroxytriazine and dealkylation, and sorption on wetland sediments and litter. Atrazine 

transport, sorption and identity loss were studied at the site, and in accompanying laboratory work. 

Sorption was effective for soils and sediments, but the more organic materials, such as litter, showed a 

stronger affinity for atrazine than the mineral base soils of the wetland cells at Des Plaines. 

Atrazine was found to degrade on those sediments according to a first order rate law. Therefore, outflows 

from the Des Plaines wetland cells contained reduced amounts of atrazine compared to the river water 

inputs. During 1991, atrazine peaked in the river due to two rain events. Only about 25% of the incoming 

atrazine was removed in wetland cell EW3, but 95% was removed in wetland cell EW4. The explanation 

is that the detention time in EW4 is longer than in EW3. 
Vegetation Responses

Water clarity is generally excellent at 

the wetland outflow.

Efforts at vegetation establishment were initially thwarted by the 

extreme drought conditions of 1988. The planting of white water 

lily (Nymphea odorata) showed small success, and American 

water lotus (Nelumbo lutea) did not survive. 

The development of the macrophyte plant communities has been 

monitored from project startup. Sixteen 2m x 2m permanent 

quadrats were established in each wetland cell. Data were 

acquired on species composition and biomass for all plants in 

each quadrat. Plants were individually measured, and a 

correlation between dry weight and leaf size was developed. Thus 

biomass could be determined non-destructively. There was an 

overall increase in species as volunteer wetland vegetation 

replaced the terrestrial vegetation of pre-pumping. 

Number of Species of

Wetland Plants

. EW3 EW4 EW5 EW6

1988 2 21 22 29

1989 9 19 14 17

1990 26 28 20 26

1991 25 33 22 27

Fourteen species were observed 

in 1990 that were not present in 

1989, and ten species from 1989 

did not reappear; these later 

being mostly upland species. 

The first year of inundation 

caused the death of many 

upland species, such as cottonwood (Populus deltoides). The growing 

seasons of 1989, 1990 and 1991 all displayed an increase in the amount 

of cattail (Typha spp.). Productivity increased from 200-400 dry grams 

per square meter in 1989 to 600-800 in 1990. The growing season of 1990 produced extensive blooms of 

macrophytic algae, predominantly Cladaphora. 
Wildlife Use

Bird populations have grown much larger than in the pre-wetlands period for the site. For migratory 

waterfowl, there has been a 500% increase in the number of species, and a 4500% increase in the number 

of individuals from 1985 to 1990. Forty-seven species of birds nested on the site in 1990, a 27% increase 

over preproject numbers. 

The fall 1990 bird survey turned up a number of interesting species, including the state endangered piedbilled grebe and black-crowned night heron, and also the great egret, American bittern, and the sharpshinned hawk. The state-endangered yellow-headed blackbird and least bittern nest successfully at the 
site. 

Muskrats have moved in, and constructed both dwelling houses and feeding platforms. And, beaver are 

now resident in the wetlands. They chewed off quadrat corner posts—most of the 256 posts initially 

placed. They attempted to dam the wetland EW3 outflow nearly every night in 1992. 
Acknowledgements

Support for the project has been provided by a large number of both private and governmental agencies. 

Contributions have been both in-kind and financial. 

Abbott Laboratories

AMOCO Foundation

Annexter Brothers

Atlantic Richfield Foundation

Badger Meter Co.

Borg-Warner Foundation

Campanella & Sons, Inc.

Caterpillar Foundation

Chauncey and Marion Deering-McCormick Foundation

Commonwealth Edison Company

Exxon Company USA

Garden Guild (Winnetka)

Gaylord and Dorothy Donnelly

Hartz Construction Co., Inc.

Illinois Department of Energy 

and Natural Resources

International Minerals and 

Chemical Corporation

J. I. Case

Kelso-Burnett Co.

Lake County Forest Preserve District

Land and Lakes Company

Material Service Corporation

Midcon Corporation

Morton Arboretum

National Terminals Corporation

Olson Oil Company

Open Lands Project

Prince Charitable Trust

R. R. Donnelly & Sons

Sidney G. Haskins

Sudix Foundation

The Brunswick Foundation

The Indevco Group

The Joyce Foundation

The Munson Foundation

U. S. E. P. A.
U. S. Fish and Wildlife Service

USX Foundation, Inc.

ISPE Outstanding Engineering Achievement of 1991: The Des Plaines River 

Wetlands Demonstration Project 

Ecological Society of America: Special Recognition Award, 1993
Research Groups

Blue horizon marker particles just after 

placement. As sediments accumulate, these 

marker particules become buried. The amount of 

overlying sediment may then be determined at 

later times.

Project research has been conducted by several 

organizations: 

College of Lake County

Wetlands Research, Inc.

Iowa State University

M. C. Herp Surveys

North Dakota State University

Northeastern Illinois Planning Commission

Northern Illinois University

Northwestern University

The Illinois State Water Survey

The Illinois Institute of Technology

The Illinois State Geological Survey

The Morton Arboretum

The Ohio State University

The University of Michigan

Western Illinois University 

For the project bibliography, project reports or other 

information, contact the not-for-profit coordinating 

organization: 

Wetlands Research, Inc.

53 West Jackson Boulevard 

Chicago, Illinois 60604 

Phone 312-922-0777 

Fax 312-922-1823