The Walnut Basin covers
approximately 2,380 square miles and encompasses most of Butler
and Cowley counties and small portions of five other counties in
south central Kansas. There were an estimated 91,700 residents
in the basin in the year 2000, and the population is expected to
grow to nearly 146,400 by the year 2040. The major streams in
the basin are the Walnut River and its tributary, the Whitewater
River; and Grouse Creek. Both the Walnut River and Grouse Creek
join the Arkansas River just before it leaves the State of
Kansas. There are two major reservoirs on the river system: El
Dorado Lake and Winfield Lake.
The annual precipitation varies from
32 inches in the western part to 34 inches in the eastern part
of the basin. Approximately 72 percent of this precipitation
falls between April and September. In an average year snowfall
varies between 10 and 15 inches. The average temperature varies
from 32 degrees in the winter to about 79 degrees in the summer.
Surface water use makes up 91
percent of the water used in the basin. The major use of water
in the basin is for municipal purposes, over 77 percent.
Irrigation uses over 10 percent, recreational uses 6.4 percent
and industrial use 3.3 percent (1997 water use data).
The economy is based primarily on
agriculture and general manufacturing. Major crops grown
include wheat, grain sorghum and soybeans. In addition, the
production of beef cattle is a significant part of the area’s
agricultural economy. The production and refining of oil and
gas is a significant component of the area economy.
Significant water management entities in the basin include the
conservation districts in Butler and Cowley counties and eight
watershed districts, which cover approximately 95 percent of the
land area of the basin. The Corps of Engineers, responsible for
the operation of El Dorado Lake, is an important water manager
in the basin. The City of El Dorado has contracted with the
Corps of Engineers for storage space in El Dorado Lake.
