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The basin is comprised largely of sandhills having an ill-defined drainage pattern and little surface runoff. Although the total drainage area at the Colorado-Nebraska State line is approximately 1,250 square miles, only 85 square miles actually contribute to the surface runoff. The basin is somewhat irregular in shape, with the major axis oriented in a southwest-northeast direction. A tributary stream, Chief Creek, joins the North Fork Republican River approximately I mile upstream of Wray. A small lake, Stalker Lake, is located approximately 2 miles upstream of Wray on Chief Creek and is maintained as a fish preserve by the Colorado Fish and Game Commission. The lake has little influence in the control of floodflows due to its small size and uncontrolled spillway. The flood plain in the North Fork Republican River valley has a moderate width, averaging from one-fifth mile in the upper reaches to one-half mile in the downstream-most reaches. The stream valley gradually slopes from the creek banks to the foot of steep bluffs which rise as much as 100 to 150 feet above the flood plain. Topographic barriers existing on the northern and southern edges of the City of Wray have forced expansion into the North Fork Republican River flood plain. In 1934, the city attempted to improve some of the bottom area so it could be developed for business purposes. The river channel was straightened and a levee built on the north bank, upstream of Adams Street. A diversion dam was also placed in the river, upstream of U.S. Highway 385, and a millrace was constructed parallel to, and on the south side of, the river channel between Blake and Cedar Streets. Lack of knowledge of the flooding potential, coupled with the availability of flat, unused land, has spurred development up to the edges of the channel. Presently, business establishments are located on both sides of the channel at Main and Adams Streets. A shopping center housing several businesses has also been constructed in the flood plain between Adams Street and U.S. Highway 385. The tracks of the Burlington Northern Railroad are also in the flood plain and have been subjected to inundation in past years, as have portions of U.S. Highways 34 and 385. The basin is predominantly agricultural with most of the area devoted to grazing or raising crops through irrigation. Few artificial ponds have been built in this area because most of the water is obtained by either pumping from wells or by taking water from several irrigation canals which run parallel to the river at different locations along the river's length. The unincorporated areas of Yuma County rank high in production of corn, sorghum, wheat, sugar beets, pinto beans, and various grains. Yuma County has a semi-arid climate with hot summers and long, cold winters. Summer precipitation in the form of intense, short- duration thunderstorms accounts for the majority of total annual precipitation. These intense, localized storms are the most 4