17 
This will (a) kill the brush and land vegetation up to the high 
level, and (5) land the floatage and much of the drift on the bank at 
a level where it will be left when the water falls. Both will help to 
give clean banks during the breeding season, open to both wave 
action and fish. 
(2) To save the rises that come in the summer as much as possible, 
so as to give as much variation as possible to the level during this 
season. 
High water will be transitory and low water the rule during this 
season. There is no chance that it will ever get up to the winter level 
and stay there long enough for the imago to develop from the egg. 1 
The effect of this varying level then will be (a) to land such floatage 
£S accumulates in the summer, and (h) to render many larvae more 
accessible to fish by compelling them to move from their shelters or 
setting their shelters adrift or stranding them. It is believed that 
if these measures are carried out the breeding of mosquitoes in the 
pond will be ipaterially lessened. 
Some special measures were also recommended for Sulphur Creek 
bayou and the bights adjacent, and the authorities were advised to 
introduce as many mosquito-eating fish as possible, the preference 
being given to Fundulus notatus , Gambusia affinis , and the smaller 
sun fish, especially the first mentioned. For that purpose the au¬ 
thorities were put into communication with the United States Fish 
Commission. 2 
BLACK WARRIOR, POOL OF LOCK 17. 
JUNE-JULY SURVEY. 
Physical condition .—This dam raises the water about 63 feet. 
The pool extends to about 7 miles above Cordova on one fork (58 
miles) and about 6 miles above the Maxine mine on the other (11 
miles, or 69 miles in all). One creek—Yellow Creek—is navigable. 3 
The pool of Lock 17 is thus quite large. There is no interference 
with its level artificially, as it is for the improvement of navigation, 
not for power, and the freshets rise normally, raising the pond leyel, 
which in low water falls to the level of the top of the dam. It 
would naturally, then, be higher in winter, spring, and early summer 
than in the fall and would thus tend to have clean banks at the 
water’s edge in the late summer and fall, unless brush holds the float¬ 
ing stuff away from the bank and prevents its landing. 
The dam was closed about the first of the year (Dec. 26, 1914). No 
clearing or preparation of any kind was made for the site. For 
1 For this about 16 days would be required. 
2 Fish of some kind has been put in, but of wbat kind we are not informed. 
3 Seven feet of water for 8 miles. 
44415°—16-3 
