[National Library of Medicine, HF0786. This transfer made: 03/07/06. Length: 00:31:45] [The Tennessee Valley Authority and the U. S. Public Health Service Present] [Malaria Control in the Kentucky Reservoir] [A documentary film photographed during the preparation of the Reservoir] [Chapter 1 Planning of Control Measures] [ Music ] [Narrator:] The Tennessee River is now a chain of lakes, chains from a flowing stream by the construction of a series of dams. The newest dam is near the confluence of the Tennessee with the Ohio River and creates Kentucky reservoir, the largest in the Tennessee Valley, 184 miles long with more than 2000 miles of shoreline. The construction of the huge Kentucky Dam built for the storage of flood waters, for navigation and for the production of electric power was expected to bring about many biological changes in the area. One of which was the creation of favorable conditions for the production of Anopheles quadrimaculatus, the vector of malaria in the Southeastern United States. This reservoir was to be impounded in a region where abundant vegetation and a mild climate had long been associated with the occurrence of malaria in partially cleared and poorly drained bottom lands. Slews and swamps along the Tennessee River. Such areas subject to periodic flooding quickly go up in willows, buttonball and luxuriant stands of annual plants which create an ideal environment for the production of Anopheline mosquitoes. While reservoir improvement eliminates many floodplain swamps and other low lying problem areas, broad shallows will be created in many localities along the reservoir margin where vegetation control will remain a problem of major concern. [Planning for prevention and control of malaria in the Kentucky Reservoir area required the co-ordinated effort of many departments of the Authority.] Detailed study of the topography of the Kentucky reservoir region was the first step taken by the malaria control staff of the Health and Safety Department and the development of plans for malaria control in the region. The sanitary engineer in charge of malaria control together with the medical malariologist, the biologist and others planned the course of action. For the specialist trained in malaria control, the 2000 miles of shoreline presented numerous challenging situations and many troublesome spots where malaria had long been endemic. These had to be located before malaria could be successfully controlled on the reservoir. Preliminary fieldwork included a botanical reconnaissance of the reservoir basin where mosquito production is influenced by the types of plants which occur in a potential breeding area. Adult mosquito catching stations were set up in barns where Anopheles quadrimaculatus commonly rest by day. These stations were periodically visited to obtain an index of mosquito population which served as a guide in program planning. All likely breeding places were located and charted. Particular attention was given to extensive swamp lands and other marginal depressions which might hold water after impoundage. Periodic dipping for larvae in likely breeding places provided information which together with the records of the adult catching stations furnished the base of reference concerning the malaria potential before creation of the reservoir. [Sign above door reads, "Henry County Office, Tennessee Department of Public Welfare, Health Dept".] Health offices in the region participated in program planning by providing information concerning past outbreaks of malaria. Available morbidity and mortality records were analyzed to gain this information. [Surveys were made of residents within one mile of the proposed reservoir to establish a current index of malaria prevalence.] Families were informed of the importance of the survey and usually responded carefully to the requests for blood films. The films were prepared by the health department nurse who knew the residents through previous contacts. Upon completion, slides were forwarded to the laboratory for examination. Information secured from adult mosquito catching stations, from larva dipping counts, from tabulations of aquatic plant life, and from malaria surveys was analyzed, correlated and plotted on detailed working maps when the field force reassembled after the completion of preliminary field appraisal. Experience on the Tennessee Valley demonstrated the futility of attempting to control Anopheline mosquito production in reservoirs of this type entirely with larvicides. A new concept was developed which involved the engineering application of permanent works. [A proposal was made by the Helath and Safety Department to "build out" extensive mosquito-breeding areas from the reservoir. This proposal recommended large-scale permanent measures such as construction of dikes, deepening or filling of shallows, and restricted land-use.] [Sign reads, "Engineering Project Planning, Tennesee [Tennessee] Valley Authority."] The Engineering Project Planning division of the Water Control Planning Department collaborated on the selection of the type of engineering project best suited for the permanent control of problem areas located by the Health and Safety Department staff. Where diking and dewatering was elected as the means of control, this division furnished cost appraisal analyses and preliminary plans with dikes, pumps and pump houses. Twenty two miles of dikes were planned to cut off large flood areas from the main lake. Assistance was also given in planning the large scale earth movements required in filling and deepening and in extensive drainage project involving the removal of more than 2 million cubic yards of earth. [Sign reads, "Highway and Railroad Division, Tennesee [Tennessee] Valley Authority."] In many instances, the Highway and Railroad Division was able to relocate railroads and highways within diked areas. This eliminated the necessity for flat slopes and expensive riprapping for protection of fields against wave action. The resulting savings in construction and clearance costs more than equal the cost of building the dikes. [Sign reads, "Reservoir Clearance Division, Tennesee [Tennessee] Valley Authority."] The Reservoir Clearance Division prepared the reservoir in accordance with specifications based on the impounded water regulations of the state health departments. Many refinements in reservoir preparation practices were developed through close cooperation between the malaria control staff and the clearance division. [Sign reads, "Department of Forestry Relations, Biological Readjustment Division, Tennesee [Tennessee] Valley Authority."] The Biological Readjustment Division is interested in developing fish and wildlife resources just as the malariologist is interested in reducing mosquito production. By planning and working together on problems involving both interests, many of the apparent conflicts between mosquito control and wildlife conservation can be resolved. Malaria control projects were reviewed with the Construction and Maintenance Division for inclusion in the overall reservoir construction. [Sign reads, "Regional Studies Department, Tennesee [Tennessee] Valley Authority."] [Title of report reads, "Tennessee Valley Authority, Department of Regional Planning Studies, Analysis of the Community Readjustment Problem in the Town of Big Sandy."] The Regional Studies Department reviewed alternative plans for the use of marginal lands in the reservoir area. For example, the decision to protect the town of Big Sandy against backwater by means of a dike was closely related to malaria control plans for nearby dewatering project. [A plan was proposed limiting human occupancy in certain areas where, because of sparse population, this method offered promise of more economical and effective malaria control.] It was proposed to limit human occupancy of the restricted areas to the hours between dawn and dusk when malaria mosquitoes commonly do not bite. This, however, permitted normal agricultural use. [Upon completion of field studies, staff members met to prepare a coordinated preliminary plan for malaria control in the Kentucky Reservoir.] Based on the findings of the field staff and the reservoir area, these proposals were drawn up as a preliminary report outlining a suggested malaria control program embracing permanent shoreline improvement measures in Kentucky Reservoir. [Title of report reads, "Tennessee Valley Authority Health and Safety Department, Preliminary Report Outlining a Suggested Malaria Control Program Embracing Permanent Shoreline Improvement Measures, Kentucky Reservoir."] The field staff reviewed the important features of the report in its final form. Due to its size, flat topography and limited scope of water level fluctuation expected during the mosquito-breeding season, this reservoir will present an unusually serious and extensive malaria problem. Portions of the reservoir cannot be effectively and economically controlled to prevent mosquito production by the usual measures applied after impounding; namely, the application of larvicides, annual growth removal, and marginal drainage maintenance. Approximately one third of the shoreline was classified as areas where prolific production of mosquitoes was expected to occur and the conditions difficult or impossible to control by the usual methods. It was for these areas that permanent improvement measures were proposed. Estimates of the initial cost of these projects, diking and dewatering, deepening and filling, land use restriction, and mosquito-proofing with limited larvicidal operations, and shoreline maintenance when compared with the initial cost of the usual control measures indicated that a greater capital investment would be required. However, in the annual cost year after year, the economic value of the proposed plan is seen in the difference between 333,300 dollars and 165,580 dollars, or 167,720 dollars in estimated annual savings. So it was planned to do a better job at a greatly decreased annual cost by using permanent works. [Although the proposed program could be justified on savings in annual costs alone, even more significant was the greater certainty of effective malaria control.] [Sign reads, "Health and Safety Department, Tennesee [Tennessee] Valley Authority."] The Director of Health saw in the proposed program the opportunity to demonstrate the application of permanent works in the control of malaria on impounded water. [Title of report reads, "Sixth Annual Meeting, Board of Malaria Consultants."] The proposal was in agreement with the opinion of the Board of Consultants, who from time to time had suggested that more economical and permanent approaches to malaria control should be formulated and applied on impounded waters in lieu of less effective methods involving high repetitive costs. [Title of report reads, "Preliminary Report Outlining a Suggested Malaria Control Program Embracing Permanent Shoreline Improvement Measures."] [Title of report reads, "Regulations Governing the Impounding and Maintenance of Impounded Waters in Tennessee."] The proposed plan was carefully examined for agreement with state regulations governing impounding of water, and forwarded to interested agencies for their consideration and criticism. Endorsement of the plan was received from the State Department of Health of Kentucky, from the Surgeon General of the United States Public Health Service, from the Tennessee State Department of Public Health, and from the International Health Division of the Rockefeller Foundation. The proposed plan for malaria control on the Kentucky Reservoir was submitted by the Director of Health through the general manager, to the TVA Board of Directors for approval. The Director of Health subsequently was advised that the general manager and board of directors approve the principles for malaria control on Kentucky Reservoir, which had been developed over a period of four years of engineering, biological, and medical study. [ Music ] [The End, Chapter 1 Malaria Control in the Kentucky Reservoir.] [The Tennessee Valley Authority and the U. S. Public Health Service Present] [Malaria Control in the Kentucky Reservoir] [A documentary film photographed during the preparation of the Reservoir] [Chapter II Reservoir Preparations] [Malaria control operations in the Kentucky Reservoir began with preparation of the reservoir basin. Early experience with impounded waters demonstrated that clearing and otherwise preparing the basin is fundamental to malaria control.] [ Music ] Initial steps in the preparation of the reservoir includes taking the contour, marking the limits of the reservoir. Normal pool elevation is marked as the basic clearing line for applying specifications for the removal of trees and brush. The distance to be cleared beyond this line varies with topography, type of growth, and exposure of the future shoreline to wave action. [Clearing of the Kentucky Reservoir basin was a long-term program. Over a period of approximately four years, 7,250,000 man hours were required.] Most of the workmen were residents of the area familiar with the use of timber cutting tools from their boyhood days. Various types of tools adapted to specific operations were required. At the beginning of each day, assignments were made, tools were selected, and the men began their work. The underbrush was cut by one crew to make it easier and safer for the timber cutting crew which followed. Felling of the larger trees is a hazardous operation requiring skill and constant precaution to assure safety. In some areas, mules were used to drag logs into the cleared area where they were piled. Along stream banks, large trees were dragged from the water's edge by tractors with winch attachments. Special bank machines developed within the authority were also used on this type of operation. Marketable timber was hauled to sawmills and cut into lumber. On all operations, care was taken to provide the workmen with an ample supply of safe drinking water. Paper cups were provided at all times and only chlorinated water was distributed. At regular intervals, field tests for residual chlorine were made. A testing solution was added to the sample then checked against color standards to give an estimation of the residual chlorine. [Other provisions for the safety of workers included: 1. Full time safety officers in the field at all times. 2. Safety education meetings for crew foremen. 3. Weekly safety meetings for each crew conducted by foremen. 4. Display of posters to encourage safe practices.] [Sign reads, "This unit has worked 439 days without a lost time injury, a total of 190,836 man hours."] These safety efforts resulted in a very low accident frequency rate. Trees on the upper limits of the fluctuation zone of problem flats were cut leveled with the ground. This not only it facilitates the use of power mowers and annual growth removal operations, but also reduces resprouting. Because of their tendency toward excessive resprouting willow stumps were treated with an aborticidal oil. Where ground conditions were suitable for the use of heavy equipment, timber and brush were cut and especially designed power rakes were used to push the cuttings into windrows for burning. Occasionally, it was necessary to sever large branches from the trunks and to cut trees into two or three sections in order to secure compactness necessary for burning. No other manual work was required. The sweeping action of the limbs and brushes as they are pushed along gives an unusually clean job. The power rake consists of a conventional bulldozer with flexible teeth hung on the blade and with supporting slides on each margin to keep the blades at the proper working elevation. The long windrows of brush and trees were allowed to dry thoroughly before they were burned. In the final stages of burning, smaller power rakes pushed the remaining material together to assure complete disposal. The end result of this operation is a clean ground surface. Both channels were marked in areas where [post-impounded] larvicidal operations were anticipated. Locations for channel markers were established by field surveys. Lands for these channels were coordinated with other reservoir navigation aids. The markers also provide aid to fishermen and to operators of small recreation boats. [Drainage has long been an effective approach to malaria control. It was an important feature in the preparation of the Kentucky Reservoir.] Drainage ditches were constructed in order that swamps and other low lying areas along the margin of the reservoir would be completely drained at the time of low water levels or would fluctuate freely with changing reservoir levels. Field surveys provided basic information for the development of drainage plans. After drainage plans were approved, ditches were staked. Construction was done usually with draglines. Where ditching was in wooded areas, stumps were removed by blasting. [ Explosion ] The shattered stumps were removed with the aid of timber hooks attached to the dragline. In swampy areas, the draglines traveled and operated on supporting mats. In some situations, drainage was required for clearing or other construction work which would have been impeded by impounded water. [Reservoir clearance extended over a four-year period. Heavy growth of coppice and annual plants occurred after initial clearance.] [Final growth removal was necessary within the marginal zone of fluctuation before the reservoir was filled. This provided a clean water surface within the range of normal summertime water level variations.] Final conditioning of the malaria control fluctuation zone required the removal of vegetation from a marginal band which varied in width from a few feet on steep banks to a wide belt in the flats. [Pointer reads, "Area to be Rebrushed."] Where topography, the type of growth and weather conditions permitted, area burning was utilized in marginal growth removal. Some woody stands were burned over. But most area burning was over grass covered flats. In situations where area burning could not be utilized, hand and machine cutting was used prior to raking and burning. Immediately below the margin of complete growth removal, tall vegetation extending into the fluctuation zone was topped. [Both mule-drawn and power mowers were used during final rebrushing.] In some cases, mowers and tees belonging to local farmers were utilized on the growth removal operations. Tee mowers were especially useful on rough terrain and in small areas. Tractor mowers cut from two to four times as much per day as tee mowers and were used principally in large flat areas. [Low stumps permitted a continuous clean cutting operation as contrasted with the interruptions caused by high stumps.] Although low stumping added to the initial cost of clearance in the fluctuation zone, the increased effectiveness and economy of the mowing operation and annual margin conditioning repaid this additional expense. Hand cutting was used were more economical methods could not be applied. After cutting, the brush was piled for burning. To reduce man hours required to clear areas of heaviest regrowth, hand cutting of sprouts was preceded by a brush harrow drawn by a bulldozer. After the harrow had passed over the area, the remaining sprouts were cut by hand and piled for burning. The piles of brush were burned. Thus, reservoir preparation provides a clean basin at the time of filling, an essential factor on the control of malaria on impounded waters. [ Music ] [The End, Chapter II Malaria Control in the Kentucky Reservoir.] [ Silence ]