This canal was formerly known as the Illinois Mississipi Canal. It ran from Hennepin to Rock Island. It was 75.2 miles in length with a 29.3 mile feeder canal from the Rock River in Rock Falls to the canal. Because of its straight course versus the undulating course of the Illinois River, it shortened the distance between Hennepin and Rock Island by 419 miles.
There were a total of 32 locks on the main canal. There was one lock on the feeder canal. The locks were remarkable for their construction from concrete–an innovation for this time.
There were 9 aqueducts. There were 67 bridges for highways and railroads ( C,B, & Q RR., Rock Island, RR., Northwestern RR.).
The Canal was originally proposed as a means to lower rates by providing competition with the railroad. Coal, salt, grain, gravel, iron and steel were transported through the canal.
The canal was first proposed as early 1834. However due to financial conditions in Illinois at this time, most public work projects were cancelled or postponed. Pressure to cheapen freight charges led to the U.S. Congress to approve a preliminary survey on the project in 1870.
The survey was supervised by Colonel Wilson, US Corp of Engineers. The survey was actually done by Graham Lowe, engineer and surveyor. His plan was for a canal 160 feet wide and 7 feet deep. The locks were to be 320 X 70 feet. Total cost was estimated to be $12,500,000.
A second survey was was performed in 1882-3. The surveyor was Major W.H. Barnyard, U.S Corps of Engineers. His proposal was that the canal begin at the Illinois River approximately 1.7 miles above Hennepin. He proposed three sites for the terminus of the canal. A board of Engineers was appointed by Congress in 1886 to assess the effects of a canal on national commerce. A favorable report was generated. Their recommendation for the terminus was Marais d’Osier. This was later rejected in favor of Rock Island.
Although multiple surveys had been done and Congress had considered multiple plans, no action was action was taken until 1890. $500,000 was appropriated to begin construction. They still had to make a decision about the course of the feeder canal from the Rock River. Ultimately, Rock Falls was chosen as the site of the origin of the feeder canal.
The Hennepin Canal construction began on September 19, 1890. Land acquisition began in 1891. Actual excavation started in 1892. At the beginning of construction estimated cost to complete the project was $6,925,900. There were delays because of the need to build both highway and railroad bridges. Areas of the canal had to be lined with clay to prevent leakage of water from the canal. An innovation was the use of concrete to build the locks. This was a cost saving measure. The locks measured 170 by 35 feet. The Canal was completed on October 21, 1907.
The Canal was never as busy as anticipated. There was stiff competition from the railroads for freight. While the canal was under construction, the Army Corps of Engineers widened the locks on the Illinois and Mississippi Rivers. This was a factor in making the canal obsolete before it was opened. The depression also had a profound effect on canal traffic.
While the canal was in service, the Army Corp of Engineers employed 50 men to maintain the canal. Their jobs were to operate the locks and to patrol the banks looking for breaks.
Beginning in the 1930’s, traffic on the canal was primarily recreational. The Canal was also used for swimming and fishing.
On April 7, 1948, the Corps of Engineers issued a navigation notice. This was a warning that there would be only limited service. In 1951, there was suspension of lock operation and non-essential maintenance. In August 1, 1970, full ownership of the canal was transferred to the State of Illinois.