1096 EXPERIMENT STATION RECORD. 



Measurements of return waters from irrigation in the same line as 

 those of previous years ' were made in 1897 on the Big Thompson and 

 its tributary, the Little Thompson, the Rio Grande, and the Cache la 

 Poudre. The measurements on the Rio Grande showed that the return 

 of water to that stream is small, but for a portion of its length it is 

 losing a Luge amount of water from its bed. For L0 miles of its course 

 this loss was found to amount to from 75 to 100 cu. ft. per second. 

 Measurements on the Cache la Poudre indicate that the losses are 

 not large enough to justify the use of any means of saving the water. 

 The Big Thompson and the Little Thompson showed a gain of 70 

 cu. ft. per second from return water. Since these gains of the streams 

 must be due at least in part to losses from eanals, measurements were 

 undertaken along about 70 miles of canal to ascertain the losses from 

 seepage. Losses were found in different canals varying from " a depth 

 of 1 ft. in 21 hours over the canal surface to a depth of over 20 ft. in 

 the same time. The average loss of canals in good condition may be 

 put provisionally at 2 ft. in 21 hours." 



Observations were made on the amount of evaporation from the sur- 

 face of a number of lakes, which indicated that the loss from this source 

 was over one-half greater than that recorded in a standard evaporation 

 tank in the college grounds, which was 11 in. 



The amounts of water furnished by the Cache la Poudre River during 

 the year, as recorded by a self registering instrument placed at the 

 point where the river flows our of the mountains and above all the 

 ditches except one, were reported in weekly bulletins, which were sup- 

 plied to the local press, " so that the irrigation interests should know 

 something of the stage of water and of the probable changes to be 

 expected." The instrument used in recording the water supply in 

 the river is described. In connection with the river records rain- 

 fall stations were maintained at various places in the mountains, and 

 in a few places temperature observations were made. These observa- 

 tions promise to be of considerable value in predicting the rise of water 

 in different mountain streams. 



The amounts of water used for irrigation on certain farms were 

 recorded as in previous years, and observations have been made on the 

 fluctuation in the level of ground water. Investigations on the water 

 supply, especially the artesian water of the San Luis Valley, were con- 

 tinued in 1897. It is believed that this valley was the bed of an 

 ancient lake, or rather of two lakes at different periods. This explains 

 why a portion of the valley is water-logged, and also why certain of 

 the shallower artesian wells furnish water which is unfit for drinking 

 purposes. A contour map has been prepared which shows that the 

 water logged soils can be drained, and it is explained that pure water 

 may be obtained by sinking the artesian wells through the second lake 

 bottom, and casing the wells to keep out the water from the upper 

 strata. 



Colorado Sta. Bui. 33 (E. S. R., 7, p. 898). 



