QUANTITY OF WATER REQUIRED. 319 



CHAPTER XX. 



THE IRRIGATION PROBLEM. 



&quot; Irrigation commenced in necessity, and has been pursued ever since for profit. It is not an 

 experiment resting u on the future to prove its advantage or uselessn ess, but a success, tested 

 by the most careful inquiry, made by the most civilized nations of the world.&quot; Hon. J/. M. Estee. 



COST or IRRIGATION Loss BY ABSORPTION AMOUNT or WATER EEQUIRED PER ACRE 

 AMOUNT USED IN FOREIGN COUNTRIES PRIMARY, SECONDARY, AND TERTI 

 ARY DITCHES BASES OF ESTIMATES OWNERSHIP OF WATER MR. ESTEE S 



VlEWS CONCERNING LEGISLATION ITALIAN AuTHORCTIES QUOTED DR. El ER s 



HINTS TOWARD A SOLUTION OF THE PROBLEM IRRIGATION AND PUBLIC 

 HEALTH. 



FROM the annual address given before the State Agricultural 

 Society in September, 1874, we have, with the author s consent, 

 taken not only the heading of the following chapter, but much 

 of its contents. Indeed, so little can be added to the report of 

 the commissioners so liberally quoted, and to Mr. Estee s pres 

 entation of the subject, that we deem it for the interest of those 

 most deeply concerned in the solution of this great problem, 

 to content ourselves with the effort to extend their benefits. 

 The Commissioners have thus counted the cost of irrigation : 



Before making an estimate of the cost of canals, it is.necessaiy 

 to inquire how much water is required to irrigate an acre of land. 

 It will leadily be understood that the quantity will depend upon a 

 number of considerations, such as the character of the soil, whether 

 sandy or clayey; upon the character of the substratum, whether 

 pervious or impervious; and upon the depth of inclination of an im 

 pervious stratum. It will also depend upon the character of the 

 cultivation. Rice and sugar fields, vegetable-gardens, orchards, and 

 meadows require more water than cereals. 



The present staples of this country are cereals. There is some 

 cotton and tobacco cultivation, which will probably be extended; 

 and, with abundance of water, we shall doubtless have a good deal 

 of alfalfa or lucerne grass. Every farmer will have a little orchard, 

 and will raise the vegetables required for home consumption. 



The evaporation is high in the interior valleys of the State, quite 

 equal to that in Madrid, where it is about thirteen inches in July. 



The amount of water lost by absorption in the bed and banks of 

 the canal, is an unknown and variable quantity. In the absence of 

 extra data upon these points, we may for the present adopt the rule 

 laid down by engineers for other countries of similar climate, and 

 estimate the loss of water from these causes at fifteen per cent. 



The rivers of California generally run full for about seven months. 

 The rains of the winter increase their discharge, and the melting of 

 the snows keeps it up, so that we may say that the streams from the 

 Sierra Nevadas are well supplied with water from December to 



