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Encyclopedia Dubuque


"Encyclopedia Dubuque is the online authority for all things Dubuque, written by the people who know the city best.”
Marshall Cohen—researcher and producer, CNN

Affiliated with the Local History Network of the State Historical Society of Iowa, and the Iowa Museum Association.


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LOCKS. Along with twenty-nine dams on the Upper MISSISSIPPI RIVER, locks create a water staircase that drops two hundred forty feet from St. Paul and Minneapolis, Minnesota, to St. Louis, Missouri. Below St. Louis, the water is naturally deep enough that dams and locks are not needed.

Locks are based on the principle that water seeks a lower level. Underground tunnels and valves are used to fill and empty the locks with water. For boats headed upstream, the lower gates are closed behind the boat. The filling valve is opened, and the emptying valve is closed. Water pressure alone fills the lock; no pumping is necessary.

The upper and lower gates, along with the emptying valve, are closed to allow the water level to reach the upstream level. When this level is reached, the upper gate is opened. The process is reversed for boats headed upstream.

Between 1.5 and 2.0 hours are needed to lock through a fifteen-barge tow holding the equivalent of 870 semi-truck loads of grain, farm chemicals, or petroleum. Barges, from 105 feet to 108 feet long, have a tight squeeze in the lock that is only 110 feet long. The depth of the water drops eleven feet with the gates open.

Mark Twain observed in 1896 that railroad competition killed steamboat passenger traffic on the Mississippi in less than thirty years. Towing fleets, he also commented, killed the steamboats' freight traffic. By 1980 amid railroad bankruptcy, barge cargoes increased more than thirty percent in less than ten years.

Between 1970 and 1979 grain shipments by water between Dubuque and Hannibal, Missouri soared from 9.02 million to 18.47 million tons. The annual river shipments of coal, petroleum, grain and other commodities rose from 22.4 to 29.4 million tons. The solitary barge held as much as fifteen jumbo hopper railroad cars and as much as 60 large semi-trailer trucks. Also putting the railroads at a disadvantage was the fact that they were responsible for paying taxes, maintenance and user fees for their transportation system--costs not a part of river travel.

In 1974 the future of locks and dams on the Mississippi came to a head as the Army Corps of Engineers began plans to rebuilt Lock and Dam 26. Joining the railroads in attempting to block the construction were the Sierra Club and Izaak Walton League. These organizations saw the Corps project as being only the first stage in a process of deepening the navigation channel and increasing commercial barge traffic all the was to Minnesota. The environmental groups also fought the construction on the grounds that the project would ruin recreational areas.

Work was temporarily halted by Federal District Judge Charles R. Richey who ruled that Congress would need to approve the work.

In October, 1978, President Jimmy Carter signed a law providing for the replacement of Lock and Dam 26. The law, however, also imposed a fuel tax on tows using certain inland rivers. The law called for a master plan for the Mississippi that would determine what part of the river was to be used for what purpose.

Watching the locking process is a favorite pastime for thousands of visitors to Dubuque. Between June and July of 1988 an estimated 77,448 people watched Lock and Dam 11, many of whom used the vantage point of EAGLE POINT PARK to observe the locking procedures.



Bigelow, Bruce, "By River and By Rail," Telegraph Herald, July 7, 1980