which was 3 feet lower than the flood of 1927. The levee grade for the existing flood-control project was based on a 3-foot freeboard above the April 1927 flood. The project considered would provide protection to the urban area of 240 acres against floods from the Arkansas River. Local interests in the community are strongly in favor of the project, and it is believed that they would form the necessary organization to meet the requirements of local cooperation as prescribed by law for other similar authorized projects. The estimated cost of this project is $159,000, of which $147,000 is the Federal cost. The estimated annual charges and evaluated annual benefits are $7,910 and $940, respectively, resulting in a cost to benefit ratio of 1 to 0.12. Some intangible benefits would result from the construction of the project; however, these benefits are not considered of sufficient importance to affect appreciably the justification of the project as reflected by the cost to benefit ratio. In view of the extreme lack of economic justification for this project, it appears that it should not be constructed at this time. It is therefore concluded that the West End portion of the existing (authorized) floodcontrol project at Little Rock should be abandoned.

GENERAL DISCUSSION

520. A study of the areas along the Arkansas River reveals that there is a serious flood problem which primarily results from high stages on that river but which is aggravated at many places by frequent high stages on tributary streams. The recurrent floods have affected many agricultural areas to the extent that property values have declined, some land is not utilized for the highest type of cultivation for which it is suited, and the welfare of adjacent communities has been lowered. Portions of urban areas lie within the flood plain and flooding at these places has affected business and manufacturing activities, and has created serious health problems. Since the report under review was made, several great floods have occurred along the Arkansas River, The largest of these recent floods occurred in May 1943. This flood exceeded maximum recorded stages along the river from the vicinity of Muskogee, Okla., to a point between Dardanelle and Morrilton, Ark.

521. No great floods have occurred in recent years from Great Bend, Kans., to Tulsa, Okla. Inquiry among local interests along this reach indicates that there is no crystallized desire for the local flood-protection projects now authorized, and that there is little possibility of developing projects for local flood protection along the main stem of the river in this area for which local interests would meet the requirements of local cooperation prescribed by law for similar projects. There is some desire for flood protection by means of reservoirs and there is also some desire for local flood-control projects on tributary streams, but these types of improvements are considered to be beyond the scope of this report.

522. In general, local interests along the river downstream from Tulsa desire local flood-control works, and advocate projects which would afford protection from major floods. They have, in most cases, expressed their willingness to meet the requirements of local cooperation; however, in a few instances, they are opposed to the construction of local flood-control projects.

523. A study of methods for providing local flood protection indicates that the construction of levees and floodwalls is the most satisfactory solution. However, diversion of tributary streams is required at some localities in conjunction with levees to provide protection from the Arkansas River. Local flood-protective works were studied in detail for areas where inspection indicated that such works might be found justified. Levee grades were based largely on the flows experienced during the flood of May 1943. Between the mouth of the Grand (Neosho) River and Fort Smith, Ark., the design flood was obtained by assuming a repetition of the May 1943 flood as modified by reservoirs which have been completed and the proposed Fort Gibson Reservoir on the Grand (Neosho) River operated for flood control. The design flood thus obtained resulted in a peak discharge of 800,000 cubic feet per second at Fort Smith. The peak discharge of the May 1943 flood reduced as it traveled downstream from Fort Smith because there was no appreciable synchronous tributary inflow within the State of Arkansas. Had the tributary inflow downstream from Fort Smith occurred as it did during the great flood of April 1927, the peak discharge of the May 1943 flood would probably not have reduced as it traveled downstream. Therefore, a design flood having a peak discharge of 800,000 cubic feet per second was retained throughout the portion of the Arkansas River between Fort Smith and Pine Bluff, Ark. Between Tulsa, Okla., and the mouth of the Grand (Neosho) River, a peak discharge of 350,000 cubic feet per second was assumed as the design flood. This flow was selected as a result of extensive flood studies made for the authorized Tulsa and West Tulsa levees. In establishing the levee grades along the Arkansas River, freeboards above the confined design flood of 1.5 and 3 feet were selected for agricultural and the larger urban areas, respectively. When all of the authorized and approved reservoirs in the Arkansas River Basin are completed, a desirable additional freeboard on the levees will be available. The levee grades proposed in this report are, in general, much higher than were considered in any previous report. 524. Investigation was made in connection with 46 projects, of which 20 were selected for inclusion in the plan of improvement. Pertinent data on all projects considered are shown in table No. 95.

TABLE No. 95.-Pertinent data on all projects considered

PLAN OF IMPROVEMENT