[Music]
[Narrator:] The Tennessee River is now a chain of lakes, changed 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 2,000 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 grow up in willows, buttonballs,
and luxuriant stands of annual plants
which create an ideal environment for the
production of Anophelene 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.
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 in 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 2,000 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 a base of reference
concerning the malaria potential before creation of the reservoir.
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.
Families were informed of the importance of the survey and usually responded carefully
to the requests for blood films.
[Fingers are pricked and blood samples taken from residents.]
The films were prepared by the health department nurse, who knew the residents through previous contacts.
[A glass microscope slide with a drop of blood on it is shown.]
Upon completion, slides were forwarded to
the laboratory for examination.
Information secured from adult mosquito catching
stations, from larvae 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 in the Tennessee Valley demonstrated the futility of attempting to control
Anophelene mosquito production in reservoirs of this type entirely with larvicides.
A new concept was developed which involved
the engineering application of permanent works.
The Engineering Project Planning Division
of the Water Control Planning Department
collaborated in 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 selected as the means of control, this division furnished cost appraisal analyses
and preliminary plans for dikes, pumps, and pump houses.
Twenty-two miles of dikes were planned to cut off large flat 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 projects involving the removal of more than two million cubic yards of earth.
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 equalled
the cost of building the dikes.
The Reservoir Clearance Division prepared the reservoir
in accordance with specifications
based on the impounded water regulations of the state health department.
Many refinements in reservoir preparation practices were developed
through close cooperation between the malaria control staff and the clearance division.
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.
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.
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.
Based on the findings of the field staff in 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.
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.
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.
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.
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
approved 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]
[Music]
[Narrator:] 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.
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 streambanks, 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.
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 level with the ground.
This not only 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 aboricidal 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 brush as they're 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-impoundage larvicidal operations were anticipated.
Locations for channel markers were established by field surveys.
Plans 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 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.
[Sound of an 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.
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.
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.
In some cases, mowers and teams belonging to local farmers
were utilized on the growth removal operations.
Team mowers were especially useful on rough terrain and in small areas.
Tractor mowers cut from two to four times
as much per day as team mowers
and were used principally in large flat areas.
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 where 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 in the control of malaria on impounded waters.
[Music]
