Lock and Dam 7 north of La Crosse is one of 29 similar structures that have shaped the mighty Mississippi River.
The facility has been open for 77 years as a Coulee Region landmark that has helped mold the Mississippi into a funnel for barge and pleasure boat traffic and help tame floodwaters.
The main lock itself is 110 feet wide by 600 feet long, and the section of dam with moving parts is 940 feet long, including five roller gates that are 20 feet high and 80 feet long, as well as 11 Tainter gates 15 feet high by 35 feet long, according to the U.S. Army Corps of Engineers. Earthen embankments and concrete spillways stretch another mile and a half eastward.
The behemoth, built at a cost of $6.77 million, attracts school classes, bus tours, collegians studying river topics and a variety of other groups, lockmaster D.J. Moser said.
Last year 4,593 recreational craft locked through. The original control building, now a visitor center, is on the National Register of Historic Places.
The structure underwent major rehabilitation in 2011 and 2012.
Shipping tonnage through the lock has yo-yoed during the past 20 years, with a downward trend during the past decade. It peaked at 15.86 million tons in 1999, settling in the 9-million-ton range in recent years.
Part of the reason is a decline in the amount of corn shipped because of the commodity’s increasing use for fuel, Moser said.