 In 1992 Mrs. Cooper donated 2,498.68 acres and the state of Oklahoma purchased the rest, agreeing to continue to pay the ad valorem taxes so the counties would not lose revenue.The WMA contains mixed prairie grass and sagebrush is found on the upland sites interspersed with sand plum thickets.of river bottom contains cottonwood, American elm, hackberry and eastern red cedar interspersed with sand plum thickets, salt cedar and mixed grassland.