Mr. Harts. 
352 DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 
e 
usually valuable, and will be vacated in favor of forests only after a 
bitter struggle. Forestation is independent of the reservoir system in 
any event, and can protect the hillsides as well without reservoirs as 
with them. 
Experience shows that most dams for the production of water-power 
are sooner or later filled with silt unless special precautions are taken 
to sluice out these accumulations into the rivers below, where they will 
inevitably form shoals and bars in the reduced currents. This sluicing 
is at best a precarious operation. Thus the dilemma of ruined reservoirs 
or injured rivers must be faced. 
The dam at Austin, Tex., which failed some years ago, was found 
to have had its storage capacity materially diminished by a large 
quantity of sediment, so much so that it is admitted that in a few 
years it would have ceased to be an effective reservoir.* Within three 
years after its completion its capacity had been reduced 38%, and it 
was estimated by Professor T. V. Taylor that in 40 years its capacity 
would have been diminished 98 per cent. No methods of sluicing out 
this sediment are yet satisfactory, and the operation, if attempted at 
all, would be attended, it is generally admitted, with great danger to 
the structure and with much uncertainty. Do the advocates of this plan 
rely on sluicing into the lower rivers these deposits of silt and sedi- 
ment? Unless-they do, it seems certain that their reservoirs would 
sooner or later be ruined. 
The wash in all parts of the country is not alike, and the rates of 
filling behind reservoir dams would vary. The scour in the arid 
regions of the West, as along the Colorado River, would probably far 
exceed the rate in the Mississippi Valley, and this would likewise far 
exceed that of New England. We are told by the advocates of forestry 
that the Mississippi River carries billions of tons of sediment annually 
into the Gulf, and it is undeniable that a large part of this sediment 
comes from the region in which it is proposed to erect dams for 
reservoirs. 
That the power that can be generated from flowing water is often 
valuable in localities favorable to its consumption cannot be gainsaid; 
nor can it be denied that this feature is relied upon by the advocates 
of the reservoir theory for its main support. Wherever great reservoirs 
have been constructed, in the past, the primary purpose has been an 
industrial one, with other considerations distinctly secondary. To what 
extent navigation will benefit from such a secondary consideration it is 
not difficult to predict. As Colonel Chittenden has stated :+ 
“The function of reservoirs will always be primarily the promotion 
of industrial ends; secondarily only, a possible amelioration of flood 
conditions in the rivers. 
*Engineering News, Feb. 22d, 1900. 
+In the Annual Report of the Chief of Engineers for 1898, p. 2878. 
