How engineers made a deal with the Mississippi: keep your 30 percent, not 31

In 1973, the Mississippi River almost left New Orleans. Behind a line of gates in a Louisiana swamp sits another river, the Atchafalaya. In 1831 a steamboat captain cut across a Mississippi bend, and what was left of it became a short channel into the Atchafalaya; then locals pulled out a giant logjam, and the door swung wide open. The Atchafalaya reaches the Gulf in less than half the distance, so it kept stealing more: 5 percent in 1900, 30 by the 1950s. Engineers made a deal with the river: keep your 30 percent, not 31. In 1973, floodwater tore a 67-foot wall loose at Old River Control. The rock held, and the 70-30 split still holds today. Sources: • Wikipedia — Old River Control Structure (Shreve's Cut 1831 · Great Raft removal 1839-1840) · https://en.wikipedia.org/wiki/Old_River_Control_Structure • U.S. Army Corps of Engineers, The Atchafalaya River Study (1951) — enlargement of Old and Atchafalaya Rivers · https://erdc-library.erdc.dren.mil/items/81b728f7-a90e-4ef8-e053-411ac80adeb3