igo2. 



FORESTRY AND IRRIGATION. 



207 



cities in the drainage basin ; so that 

 practically upon many of the streams 

 of the state, as will eventually be the 

 case upon all, every drop of water is 

 used over and over again. I have said 

 that the amount of use that may be 

 made of the water supply is dependent 

 upon the amount of water available ; 

 this will, of course, depend upon the 

 precipitation and the area drained by 

 the stream and its tributaries and upon 

 the general nature of the country ; a 

 sandy and level drainage area giving 

 far less run- off than an equal area cov- 

 ered with rocks ; and similarly, a tract 

 covered with forest permitting a less 

 violent discharge, although a more con- 

 tinuous and protracted flow than a sim- 

 ilar tract denuded of all vegetation. 



In the investigation of our w'ater sup- 

 ply the stations established may first be 

 classed generally in two divisions : those 

 which are of a more or less permanent 

 nature that is, are expected to be con- 

 tinued for a considerable term of years, 

 and those which are of a temporary 

 character, or which are expected to be 

 kept up for from one to four or five 

 years at the most. Those of the first 

 class are generally located upon the 

 most important streams and at the most 

 practicable points upon these streams 

 for deriving correct information con- 

 cerning the flow. Those of a tempo- 

 rary character are established upon the 

 smaller streams, either at the most im- 

 portant points or at points where especial 

 information is desired, and at interme- 

 diate points upon the main streams. Of 

 a permanent character may be named 

 those stations w^hich are situated at the 

 mouths of the canyons of the large 

 streams and those stations situated near 

 the boundaries of the state ; for exam- 

 ple, upon the Rio Grande, in Colorado, 

 both stations maintained at present are 

 of a permanent nature, one of them being 

 practically where the water debouches 

 from the mountains, and the second 

 being near the point where the river 

 crosses the line between Colorado and 

 New Mexico. Of a temporary nature, 

 so far as the Geological Sur^-ey is con- 

 cerned, at least, are such stations as 

 those upon the tributaries of the South 

 Platte and of the Arkansas and upon 



many of the western streams of the 

 state, where only general information 

 is desired as to the amount of water 

 available for different purposes. 



All stations established, whether of a 

 permanent or of a temporary nature, 

 have some especial reason for their estab- 

 lishment, however, and these reasons 

 may var}' as the uses to which the water 

 is put vary. In one place the investiga- 

 tion may be simply for the purpose of 

 diverting the amount of water available 

 for irrigation directly from the stream ; 

 in another case it is desired that the 

 amount which goes to waste in a given 

 stream ma}- be known in order that if 

 possible this loss may be prevented and 

 thus reservoirs be made available. Or 

 a station may be established in order 

 that the discharge of a stream may be 

 known with reference to the power that 

 might be developed from this stream ; 

 or, again, a station is established for 

 the purpose of ascertaining the amount 

 of w^ater available as a city water supply- 

 upon some of the smaller tributaries of 

 the Tiiain streams high up in the moun- 

 tains, perhaps. 



One of the principal uses to which 

 water is put in Colorado is irrigation, 

 and consequently some of the most im- 

 portant information to be derived is for 

 this purpose. Colorado is divided into 

 six irrigation divisions, and each of 

 these is in its turn divided into a num- 

 ber of irrigation districts, the divisions 

 being governed in general by a superin- 

 tendent who is under the direction of 

 the state engineer, and each district 

 being governed directl}' b}^ a water com- 

 missioner, who reports to the superin- 

 tendent. Many of the stations estab- 

 lished have been for the assistance of 

 the water commissioners in properly 

 dividing the water of the .streams among 

 the various consumers, this being the 

 especial province of the state engineer, 

 wlao cooperates most full}' and heartily 

 with the work of the Divi-sion of Hy- 

 drography in this respect. 



I shall not go into the details of the 

 different irrigation districts at this time, 

 but mention in brief the different irriga- 

 tion divisions into which the state is 

 subdivided, with particular reference 

 to the different drainage basins. These 



