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Show II. Summary of Experience In order to hasten completion of the project, with the advent of World War II, plans for the complete clearing of the site in accordance with the South Carolina State Board of Health regulations, were modified to the extent that 47,000 acres of standing timber were left in the center of the reservoir. (The cleared strip varied from one-half to 1 mile from shore.) An entomological survey conducted after impoundment demonstrated stupendous production of malaria mosquitoes in the region, particu- larly in uncleared areas. In addition, the development of wildlife areas were improperly planned. Two wildlife refuges (Potato Greek and Jack's Creek), of a type favorable to the high pro- duction of malaria mosquitoes, were located in regions with a relatively high human population. Many sus- ceptible humans were thus exposed to vast numbers of the insect vectors of malaria. Improper early management permitted small colonies of aquatic plants to gain a foothold in the reservoir. In 1944 there were less than 100 acres of alligator weed in the Santee Reservoir. By 1948 the infestation had in- creased by thousands of acres. Despite expensive later control ($13,000 were spent in fiscal year 1947) coloni- zation has so progressed that eradication of the obnoxious plant has now become a tremendous task which is prob- ably beyond the realm of economic feasibility. Lack of early recognition of a potential problem has immeasurably increased the expense involved in achieving control of the plant and of the malaria mosquito breeding associated with it. The Extent to Which Projects Have Accomplished the Design Purpose Nearly all projects now operating are accomplishing the purposes for which they were built. Many have been altered since original construction to make them more satisfactory. The agencies have learned much from the construction and operation of these projects and have put this knowledge to use not only on these projects, but on new projects. Some of the original faults or lack of techniques are cited herein to indicate the types of prob- lems that were encountered. Similar types of problems will arise in new programs but in the development of similar projects the agencies have adopted the appropriate improvements. On a number of irrigation projects, salts, toxic to plant growth under irrigation, have risen to the surface. Many alkali areas within irrigation districts are no longer pro- ductive. Such lands can be found in the Belle Fourche project in South Dakota and in many other projects. The charges applying to such lands are held in suspense accounts so that when it will be possible to remove the salts or to raise crops on such lands, they may bear their porportionate part in the project cost. The remainder of these projects is successfully serving the purpose for which they were planned. The alkali problem is also intimately related to water- logging of the land from lack of drainage. This problem is now cured by providing adequate drainage and flushing. These measures have materially added to the cost of some projects. Other types of soils, such as "hard-pan," "grease- wood," or "gumbo," are highly impervious and unfit for cultivation. These types of land have been excluded from some projects as in the case of the Shoshone, Belle Fourche, and other projects. Engineeringly, these irrigation projects are sound and supplied water to the land. This was the real design purpose. With respect to the acreage of land brought into production, however, some projects fell short of the goal, because of a definite lack of adequate knowledge or basic data on soils. On many of the privately constructed irrigation projects, especially the smaller ones, serious trouble has developed so that now a critical condition exists. Much of this is due to lack of adequate financing, poor engineering, and the use of temporary structures. There are many of these small projects that must be rehabilitated or much of the present economy will be lost. Federal flood control projects, though having been oper- ating for only a few years, have in general been successful. Many locally constructed projects have not had as good a record, although that of the Miami Conservancy District has been an outstanding success. Some have proven in- adequate, and have been enlarged to provide greater bene- fits. The Hogan Dam on the Calaveras River, Calif., built by the city of Stockton, is to be replaced by a larger struc- ture to provide additional protection and at the same time supply irrigation water. The town of Bonners Ferry, Idaho, built levees to protect it from the flood waters of the Kootenai River. These have recently been materially modified and strengthened by the Corps of Engineers. Watershed management programs have not yet gone beyond their initial or trial stages of construction. Con- sequently, they have not as yet demonstrated whether or not the full benefits claimed will be realized. Drainage projects notably have not produced the results originally contemplated because of lack of adequate de- sign, financing, and operation and maintenance. They were primarily of a private or local interest and had for their purpose the draining of a small area without sufficient consideration of the amounts of water to be derived from either the drained land or its surroundings. Conse- quently, they failed because their ditches were inadequate to carry the amount of water which actually had to be conveyed. Navigation projects generally have been engineeringly sound. A few have not developed the traffic for which they were designed although the project successfully re- duced freight rates in the locality. This was the case in the Illinois-Mississippi canal in northern Illinois. Other navi- gation projects have been greatly modified, as on the Ohio and Warrior Rivers, where new types of barges and tows have developed. It has been necessary to deepen harbors 403 |