Exactly how much water is flowing under the Interstate 20 bridge at any given time is a mystery — unless you’re one of two men in the little silver boat running back and forth across the giant Mississippi River.

One is an applications engineer and the other is employed by DIMCO, or Vicksburg-based Digital Information Mapping Company.

“In the past five years, we have provided over 1,200 surveys of river currents for discharge calculations, river stage predictions and engineering studies on the Mississippi River, but never with the depths, velocity and sediment we are experiencing now,” said Tim McCarley, who has worked for DIMCO since its beginning 20 years ago.

The company was founded by Vicksburg native Stuart Green with two men, including McCarley, a pickup, a boat and a contract from the U.S. Army Corps of Engineers.

Today, DIMCO has more than 30 employees, eight boats and two offices.

McCarley, manager of the Vicksburg office, said DIMCO is working harder than ever to collect data from the historic flood.