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, " REPORT ON FLOOD AND ::;ROSION PROBW"S AHD COHTROL KIOTiA AND BIJOU Crtc-:2K BASINS IN COLORADO By l , " F. L. Boydston, Jr., Engineer Colorado Water Conservation Board -:*- ojl- .;l- ~l- * During the latter part of September, 1949 the author, representing the ],10rado Water Conservation Eoard, in the company of other interested parties made a comprehensive tour of the Kiowa and Bijou Creek basins. The purposes of 'O~le inspection of the basbs were three-fold: (1) to determine the extent of Glmage to crop and grazing Itlnds, roads, bridges, towns and communities by un- 'Clntrolled floodwaters, and wind and rain erosion; (2) to inspect the types of ?rosion control measures practiced in the area by the Soil Conservation Service, ct,her constructing agencies and private landowners; and (3) to determine gen- ',rally the most critical areas in which conservation measures are needed to pro- cect the basins. I In the northern portion of the basin, from approximately U. S. Highway 36 to the South Platte River, damage is caused principally by excessive flood "raters which arise in the upper basin and inundate the fields and highvrays, wash- ;.ng out bridges, fences, livestock and buildings. These floodwaters contain such :lebris as trees and portions of vrrecked buildings which accumulate at bridges and act as dams, causing inundation of much fertile grazing and crop lands. The pressure on the bridges from the water thus backed up, aggravated by eddying currents set up nem' the brid~e approaches, seriously damages or completely washes out the bridges. Under such conditions familieS are often completely isolated. Upon recession of the floo~raters, enormous quantities of silt are de- posited on the flooded lands, at times to a depth of as much as one foot. The silt originates mainly in the headwaters areas and is carried in suspension by the floorn~aters to areas where the flow is detained sufficiently to cause the deposition of much of the silt load. At times of flood, the waters often are So percent silt laden. In addition to such iesc~ibed damage, scouring takes place on the eastern banks of the main channels of Kiowa and Bijou Creeks during periods of excessive rlmoff and floods, which has resulted in the shifting of the channel to the east as far as a quarter of a mile in places. It is thought ~hat the principal reasons for this movement of the channel is the scouring action of high velocity -1-