The Washita River flows through the park for about a mile and a quarter of its length. Judging by the wide, low-lying floodplain that is apparent on either side of its banks, the Washita used to flood quite severely on an at least occasional basis. One documented flood during the Dust Bowl era was enough to convince the government to install some of the first flood control dams in the nation on upper tributaries of the Washita, west of the present-day park. The dams obviously had a significant effect on the natural flooding regime of the river.
Within the park itself but before its establishment, the river itself was diverted into a man-made channel, at least for a time. While the river has returned to its original course, the artificial river channel today acts as a narrow, ephemeral wetland.
There is also evidence that the river at one point flowed along a different course of its own accord. Along this suspected route the vegetation is much more dense than would normally be expected. At the same time, this vegetation lies parallel to an abandoned railroad line which may itself be affecting the hydrology of the site in myriad ways. In any case, water is a very important part of the story at Washita Battlefield.
