23 



ijs ;;iibject to very little rlumg-o. This makes tapping the river coni- 

 parativol}' easy. In the 25 miles there are no less than fifty -four 

 ditches takino- water from the river. These ditches, especially those 

 built some years ago, are for the most part small, having l)een built 

 by the irrigators themselves, three, four, or half a dozen farmers join- 

 ing in thi> construction of a common ditch. Most of the ditches of this 

 class were built for the irrigation of lands lying contiguous to the 

 river bottom, and little or no difficult work was encountered. 



When the higher valley lands were settled several large canals were 

 constructed which take th(>ir sui)})ly well up on the river. 



USE OF WATER. 



DIVEKSroX AM) DISTRIBUTION, 



Not in the histoiy of irrigation from the West Gallatin has there 

 ever been any regulation as to the extent of the diversions made 

 })ecause in normal seasons the rivers supply has been sufficient to 

 meet all demands. But during seasons of short supply, only one or 

 two of which have as yet been experienced, the supply while sufficient, 

 had proper division been made, was not equal to the demands, and on 

 the lower part of the streams a severe shortage was felt, and a stage 

 is l)eing reached where the demand will more often exceed the supply 

 and the old regime will have to give place to some system of stream 

 control. 



The methods of distributing water from the larger canals to con- 

 sumers have not reached a settled state. On the West Gallatin Irri- 

 gation Compan3''s two canals the amounts diverted by laterals are 

 computed' b}^ a hydraulic formula. The factors necessary are, first, 

 size of opening of the lateral head gate; second, head of water in 

 canal over opening; and, third, the velocity of flow through opening, 

 which is obtained for diii'erent heads from Trautwine's Engineering 

 Handbook, The actual discharge is assumed to be 70 per cent of the 

 theoretical discharge deriv^ed from the above factors. All discharge 

 measurements are expressed in Montana inches. 



On the Kleinschmidt canal, within the last 3^ ear, the current meter 

 has been adopted. Up to the time of its adoption the diversions by 

 laterals were in the majorit}^ of cases left to the ditch rider, whose 

 estimate of a lateral's discharge was accepted as the probable flow. 



On the Farmers canal trapezoidal weirs have been constructed in 

 the laterals near their points of diversion. But for want of proper 

 care in their maintenance they are in the majority of cases in poor 

 condition, and are but little better than no measuring device at all. 



On the Kughen ditch and a majority of other larger ditches no 

 system of measurement is employed, the amount diverted by the 



