HISTORY OF THE CHICAGO SANITARY AND SHIP CANAL AND CREATION OF AN AQUATIC 
NUISANCE SPECIES DISPERSAL BARRIER

Phil Moy.  Wisconsin Sea Grant

Though historically separated, the Great Lakes and Mississippi River drainage 
basins were occasionally joined by a wetland called Mud Lake. During wet periods 
of the year, the lake was navigable by canoe. Explorers in the 17th century 
recognized the value of a water connection between the Great Lakes and Des 
Plaines River. Like other canals built around the Great Lakes, the Sanitary and 
Ship Canal began on a much smaller scale and was expanded to what we see today. 

The Illinois and Michigan Canal, built in 1858, joined Lake Michigan to the 
Illinois River at LaSalle-Peru. This small canal followed a course essentially 
parallel to the present-day route of the Sanitary and Ship Canal. Unlike the 
present day canal, it was narrow and shallow, requiring the use of small barges 
to move people and goods east to Chicago or west to the frontier. Pumps lifted 
water about 15 feet from the Chicago River into the Canal; the water then flowed 
by gravity to the Illinois River.

Pumping the water into the canal had the indirect effect of improving water 
quality in the Chicago River. Sewage-laden water pumped from the river was 
replaced by lake water. This improvement in water quality planted the idea for a 
larger, free-flowing canal that would improve the undesirable conditions of the 
Chicago River.

Construction of the Chicago Sanitary and Ship Canal was completed in 1910. The 
larger, deeper canal could accommodate full-size vessels and allowed free-flow 
of the Chicago River into the canal. This essentially reversed the flow of the 
Chicago River and flushed Chicago's sewage downstream. Today, this century-old, 
man-made canal is the only aquatic link between the Mississippi River and the 
Great Lakes drainage and forms a two-way avenue for invasive species dispersal.  
The canal is used for transportation of freight between Lake Michigan and the 
Illinois Waterway, and to carry wastewater away from Lake Michigan, Chicago's 
drinking water supply. Recreational vessels frequent the canal, but it is not 
used for water skiing or swimming.

The National Invasive Species Act (NISA) of 1996 authorized the U.S. Army Corps 
of Engineers to carry out a demonstration study of an aquatic nuisance species 
dispersal barrier in the Chicago Sanitary and Ship Canal.  The objective of the 
study is to slow or prevent the dispersal of invasive species via the canal.  No 
migratory species traverse this man-made canal, but the barrier is expected to 
affect native as well as invasive species.  A multi-agency advisory panel 
ensures representation of the myriad interests in the canal and development of 
the barrier.  The panel members identified potential methods and recommended an 
initial approach.  Due to the commercial uses of the canal and its importance to 
Chicago's drinking water, physical barriers and canal closure are not practical 
short-term alternatives. 

The demonstration study will begin with installation of a micro-pulsed DC 
electric barrier designed to deter fish, rather than stun them. The study will 
add methods to target other species as funding allows.  Monitoring of the 
barrier performance will help determine effectiveness of each method.  
Conceptually, the full-scale barrier will consist of a two-barrier, redundant 
system in a restricted reach of the canal.  Construction of the electric barrier 
was completed in December 2001; the barrier is expected to be operational in 
early spring of 2002.