fa 
rs without adding materially to the malaria-contro] 
The naked stems of this species furnish a minimum 
ter surface for anopheline breeding 
(Rozeboom and Hess, 1944). Con- 
s along margins would not only 
ffective substitute for the destruc. 
in the marginal zone of reservoi 
problem (Hinman, et al, 191). 
plant edge or "intersection-line" on the wate 
and provide a mechanical barrier to oviposition 
sequently, extensive propagation of this specie 
benefit waterfowl but should also serve as an © 
tive practice of cutting and filling. 
Diking and Dewatering 
Another malaria-control procedure that has been used by TVA is the diking-off 
of troublesome anopheline areas and dewatering by pumping during the malaria 
mosquito breeding season. This measure can be highly beneficial to waterfowl if 
reflooding of these units occurs at the conclusion of the malaria season ~~ which 
is about the time when the fall migration of ducks starts. With suitable timing 
of reflooding, dewatered areas provide excellent feeding habitat for waterfowl 
by production of useful native vegetation or agricultural crops. Additional 
particulars are presented further on in this report. 
Land-Use Restrictions 
A malaria~control recourse used by TVA is the restriction of land-use within 
a one-mile zone of reservoirs. People are allowed in this zone only in the daytime 
during the anopheline breeding season. Large tracts of such restricted land exist 
on the Kentucky Reservoir within the Kentucky Woodlands National Wildlife Refuge, 
and another large restricted district is partly within the Tennessee National 
Wildlife Refuge. Refuge maintenance in these areas is of importance to malaria 
control because it aids conformity to the human-use restrictions. These areas 
can be of special value to waterfowl because in them permanent pools for marsh 
and aquatic habitats can be developed without contributing to the malaria hazard. 
Methods of Improving Waterfowl Habitat 
Potentialities for waterfowl development on the TVA reservoirs are confined 
largely to the shallow water sections that occur in the upper part of the impound- 
ment and in embayments of tributary streams. These locations'usually offer an 
advantageous interspersion of land and water due in part to low, ridge-like islands 
and peninsulas that protrude above water level. In these favorable areas there 
are several methods of improving habitat for waterfowl. Some are far more impor- 
tant than others. The provision of un-flooded farm crops may result in selective 
attraction of certain kinds of waterfowl instead of numerous species. This does 
not result in full waterfowl utilization of an area. In those areas where pos- 
sibilities are limited, application of all possible methods may be essential for 
maximum attraction of ducks and geese. Obviously, the combinations of techniques 
that can be applied will vary for different reservoirs depending on local condi- 
tions. 
Practical means of habitat improvement applied experimentally by the Fish 
and Wildlife Service during 10 years of investigations on the lower TVA reservoirs 
include the following six procedures: (1) Developing sub-impoundments and dewatered 
