1939, James Stevens Simmons, Malaria in Panama, Baltimore: Johns Hopkins Press, Chapter 7 “Sanitary methods used for the control of malaria in the Canal Zone,” p. 189,
In many of the vast sea-level swamps of the Atlantic side, no slope whatever can be obtained, and here dependence is placed on a grid system of intercepting earthen ditches, communicating with seawater at each end whenever practicable, to insure quick run-off of rain water and thorough salination of every part of the swamps.
1989, Michael Renner, “Enhancing Global Security” in Lester R. Brown et al., State of the World 1989: A Worldwatch Institute Report on Progress Toward a Sustainable Society, New York: Norton, p. 142,
Disputes revolve around water diversion or reduced water flow, industrial pollution, the salination or siltation of streams, and floods aggravated by soil erosion.