This is Roald Tweet on Rock Island.
Montgomery Meigs worked for the Rock Island District Corps of Engineers for fifty-two years, before retiring in 1926 at the age of 79. In the end, he had nothing to show for his work: it was all under water.
Meigs was the son of the Montgomery Meigs who had helped Robert E. Lee map the Rock Island Rapids in 1837. Montgomery Meigs junior came to Rock Island in 1874, fresh from Harvard College and the Royal Polytechnic Institute of Stuttgart, Germany. He was put in charge of the survey of the Mississippi River from St. Paul to LaCrosse, Wisconsin. Congress was about to authorize a deeper four-and-a-half-foot channel on the Upper Mississippi, a project that promised to take decades, given the tedious and expensive dredging and rock-blasting procedures then in use.
Meigs was never one who could let things alone; he was always tinkering, never content until he had found the simplest and cheapest solution. Even while completing his survey, he began experimenting with simpler ways of making a deep channel. "Why not," he thought, "let the river do some of the work." It didn't take a Harvard degree to tell Meigs what all boys know: that narrowing the outlet of a rain puddle makes the water move deeper and faster. The Mississippi was simply a larger puddle. Restrict the current to the center of the river, and the swift water would scour the bottom and deepen the channel without dredging. Meigs experimented with crude dams sticking out perpendicular from both shores to constrict the channel.
They worked perfectly. Over the next two decades, the Corps of Engineers constructed hundreds of wing dams between St. Louis and St. Paul using willow and crushed rock from the riverbanks. During low water, the dams restricted what little water there was to the middle of the river to keep the channel deep. The rest of the year, they were submerged to let high water flow unrestricted.
Montgomery Meigs’ wing dams are still in place, doing their job. Unlike other show-off engineering marvels such as the Sears Tower or Hoover Dam, Meigs' wing dams work invisibly, unnoticed and unsung.
Rock Island Lines with Roald Tweet is underwritten by Augustana College, Rock Island, Illinois.