i8 The Colorado Experiment Station. 
it at the proper time or lose the water until his turn at the next 
rotation. 
This method is best applicable evidently in the cases where 
the amount of water flowing into the lateral is constant. This 
is rarely the case for the main ditch, and consequently the small 
laterals, are affected by the fluctuations of the main stream, shown 
in Bulletin 55. Where water is distributed from reservoirs, then 
the flow may be kept uniform. The necessity for restriction to 
certain times is distasteful to many. But by common consent, 
methods are used which are leading to this system. With 
the increasing pressure for the greatest benefit from the amount 
of water available this method will gradually extend in use under 
the conditions where it is best adapted. With the varying streams 
and varying flow, the method is not so equitable as the division 
of water as it comes. It is already becoming customary in ditch 
administration in Colorado, to keep records of the amount of 
water which is taken into the canals. It will become increasingly 
desirable and even necessary. For the larger ditches the amount 
of water which is taken into the ditch for different depths, is 
officially determined by the state engineer or his deputies. A 
similar rating of the lateral ditches may be made, or weirs may 
be used with greater accuracy. It will be possible to use a modi¬ 
fied time distribution, so that each will be given the water long 
enough to give the same quantity. The unit could be varied, so 
as to bring the irrigations a convenient time apart. The success¬ 
ful operations of such a system would require an intelligent super¬ 
intendent, who has the confidence of the users, and a wide-spread 
knowledge among the users. 
In the distribution of water from small reservoirs, where there 
are but few interested, and where the different owners do not 
care to use the water at the same time, some such arrangement 
is necessary. With the weir measurement it is possible to keep 
account of the amount used by each person, so that the water 
may be divided in proportion to the rights of each. 
This practice is spreading, and it is found that where once 
begun it is rarely abandoned. Within its own limitations it is 
an excellent method. 
modules. 
It is not possible to secure a module satisfactory in every 
respect or to meet all conditions. The following are desirable 
conditions which should be met by a module. Most of these con¬ 
ditions were recognized centuries ago by the magistrates of Milan. 
Some are manifestly of different importance. 
1. Its discharge should be capable of being expressed in cubic 
feet per second. 
