THE TEXAS ACADEMY OF SCIENCE. 
THE SILT PROBLEM IN CONNECTION WITH 
IRRIGATION STORAGE RESERVOIRS.* 
BY J. C. NAGLE, ASSOC. M. AM. SOC. C. E., 
Agricultural and Mechanical College of Texas, 
College Station, Texas. 
During the spring of 1899 Mr. Elwood Mead, of Cheyenne, Wyoming, 
Expert in Charge of Irrigation Investigations for the U. S. Department 
of Agriculture, assigned to me a portion of the work in connection with 
the investigation of certain economic questions relating to the effect of 
silt upon irrigation systems making use of storage reservoirs, the effect 
of silt upon canals and the effect that the use of certain waters would 
probably have on vegetation to which they might be applied. Later on 
it was decided to have the results of observations at other points pass 
through my hands also, and I have only recently completed my progress 
report for the present year, covering the results of measurements on 
certain streams in Texas, New Mexico, Arizona and Wyoming. A few of 
the results as contained in that report will he here presented. 
In published analyses of river waters the quantity of suspended mat- 
ter is sometimes given in grains per gallon and sometimes in parts 
per 100,000, hut in such analyses as I have observed the results were 
obtained gravimetrically. Now, in a storage reservoir, it is not the ratio 
of the weight of dried silt to the weight of the water that the reservoir 
would contain that is wanted, but the ratio by volume, for when the 
capacity of the reservoir is diminished its value is likewise impaired. 
In Power systems this is not always the case, though sometimes it is. 
Mr. Mead desired, therefore, to know the ratio of silt to discharge, by 
volume, for certain streams, and also, incidentally, the proportion of silt 
carried at different depths in these streams, and he outlined a plan from 
which it has been found necessary to depart somewhat, in some cases, 
as occasion demanded. The plan was to collect four samples for each 
*Read at the Waco meeting of the Texas Academy of Science, December 29, 
1901. 
