REPORT. To His Excellency, Governor FRED'K F. LOW; Surveyor-General J. F. HOUGHTON; and Attorney-General J. G. McCULLOUGH: GENTLEMEN :—A survey, authorized by an Act of the Legislature of California, approved the twenty-sixth of March, eighteen hundred and sixty-six, "of a route for a canal" from the Sacramento River to navigable water in Cache Creek Slough, in Solano County, has been made under instructions dated twenty-third of May last, communicated to me by the Attorney-General. Section one of the Act prescribes: First-That the route to be surveyed should commence "at some point on the Sacramento River near the county line of Colusa and Tehama;" and Second-That the design of the canal is" for the purposes of irrigation as well as ordinary canal navigation." The objects of the Act, as expressed in its title and substantially repeated in the second section, are "to develop the agricultural interests" by means "of a canal for the purposes of irrigation and inland trade in the Counties of Colusa, Yolo, and Solano." A hasty reconnoissance of the Sacramento River made by me in April. last, had given me reason to believe (what our surveys have since proved) that the elevation of the river and country at or near the county line of Colusa, was not sufficient to water effectively the counties named. The sparse and scattered population, and the correspondingly scanty traffic of the country through which the survey was to be made, would not at the present time maintain a canal simply of navigation, if now existing, much less induce or promote the building of one. On the other hand, a canal of irrigation would immediately impart such life to the country as to create a traffic that would support a canal of transportation, if existing, perhaps build one, if required. The object being "to develop the agricultural interests," and the development of these interests being so much more dependent upon a canal of irrigation than upon one of navigation, if a choice is required to be made between the two, the canal of irrigation must have preference. Irrigation and ordinary canal navigation are, in my opinion, impracticable in the same canal and through the counties named, at any reasonable cost; the conditions required for the latter being the least current possible consistent with the supply of water required for its lockage and the unavoidable waste of the canal; and those for a canal of irrigation, the strongest current consistent with the purposes of its construction and its own safety. A survey from any point very near the county line named, or a canal planned for ordinary canal navigation, would not therefore accomplish the objects sought. It is fair to assume that if the information upon the subject of the relative heights of the water surface in the river and of the plain to be passed over, since developed by the survey, or even that obtained by my reconnoissance in April last, had been before the Legislature, they would not have specified any point near the county line of Colusa as the initial of the route, nor a plan combining ordinary canal navigation, as I have defined it, with the essential of irrigation. Stating these facts to the Attorney-General in a letter dated the eighteenth of May last, I expressed the fear that the provisions of the first section above quoted would be found to conflict with the intent, and advised an interpretation of the Act which would allow the Engineer to select the most suitable point within the Counties of Colusa and Tehama for the initial of the route, and in the plan to combine with the canal of irrigation the best navigation that such canal admits of at reasonable cost. These suggestions were approved, and the instructions given to me accorded with them. We understand, then, the Act with this construction, to require a survey of a route for and a plan of a canal for irrigating the Counties of Colusa, Yolo, and Solano, which will at the same time afford facilities for inland transportation and trade, but which will not be confined to the gentle current of ordinary canal navigation. Although it is not expressed in terms that the supply of water for the canal is to be drawn from the Sacramento River, the intention of the Legislature is inferred from the general tenor of the Act. If there is any doubt upon this question, the reason for not searching elsewhere for a supply in whole or in part, and of ascertaining with certainty if it is practicable to secure it, will be found in the sequel. Of the route, the Act requires the Engineer to "return, under oath, if a practicable one can be found for a canal for the purposes of irrigation as well as ordinary canal navigation," etc., etc. It is, however, silent upon the questions of the position, size, form, slope, capacity, quality-in short, the character and plan of the canal, which devolve on him to determine. That routes from many points on the river are possible for the purposes named, is without question. The conditions of "a practicable route" are different, and as I understand them, require First-Adequate supply of water; and Second-Equivalents, in the prospective benefits and advantages to result from the use of the canal, for the construction of one upon the route. The first admits of accurate determination, and has been ascertained. In the second, the cost of construction upon a route carefully and finally located may be closely estimated from experience gained in canal construction in the United States; and an approximate estimate has been made, in much detail, upon a preliminary and experimental survey. But for the full equivalents for the building of the canal, in the benefits and advantages which the canal is capable of yielding, we have no examples in our own country of a canal of navigation combined with great capacity for irrigation and water power. We can readily find them, however, in other countries. This question, upon which depends in a great measure that of the practicability of the project, I will first examine. The effect of canals of irrigation is not only to increase the production and the productiveness of the irrigated region, and to employ and maintain a numerous rural population, but to multiply both; to increase the quantity and cheapen the cost of food, to ensure regularity in its supply, to contribute to the prosperity and wealth of surrounding districts, and to the support and comfort of population outside of its own limits. That the population of California must rapidly increase, is a question upon which there can be little doubt. The genial and salubrious climate of the State; her fertile soil, with its capacity for varied and rich production; her wealth of mineral and exhaustless water power; the commercial advantages of her position, Asiatic commerce springing up with the advance of the Pacific Railroad to her commercial emporium, the two opening new markets abroad and in the vast interior of the continent-all give assurance of it. Whatever will secure cheap food and steady and remunerative employment to and increase the comforts of her growing population, is of such interest to the State as to deserve to be cherished and promoted by her; much more so any scheme which will do more, by protecting the State against a failure of crops like that of the season of eighteen hundred and sixty-four, amounting almost to famine. Although the best lands were under cultivation that year, the losses sustained by her people on account of the scarcity of food probably exceeded the estimated cost of the proposed canal, which, if built, would forever protect them against such disaster. The question we are now examining, with its kindred projects of utilizing the waters of other parts of the State, I believe to be such. With her great advantages in other respects, there is one great draw back to the State in the scanty rain-fall upon her extensive plains and valleys. While the average annual rain of the Atlantic States and of the west of Europe ranges from thirty-six to forty inches, that of California, as shown by records kept at Sacramento City since the year eighteen hundred and forty-nine, is less than twenty inches. Of the seventeen years of observed rain, we find ten seasons with less than the average, four of them having less than twelve, two less than eight, and one less than five inches of rain. The recurrence of these, with a dense population in the State, would cause much suffering, and might inflict upon the State the horrors of a famine. A sure preventive is within the reach of her people. The moisture which is in such deficiency in the plains and valleys, is in abundance in other parts of the State where it is condensed and reserved as if for their special use. They have but to turn from their channels the copious streams which the suns of spring and summer send down from the snowclad mountain ranges of the State, and spread their treasures of moisture and fertilizing matter over the thirsty lands, to make them fruitful as Egypt, and to have assurunce of unfailing crops. This use of melting snow, which must in time become a necessity to California, is but an expedient for multiplying the production of the most fertile lands and of enriching those of poorest quality in other countries. It is not confined to those of scanty rain like our State, but is employed in some where the annual rain-fall is double that of California, and as abundant and as well distributed throughout the year as it is in the Atlantic States of our Union. The irrigation of land has been but little practiced by American farmers, and to most of them it is known only by name, although it was probably the earliest art practiced by man, has been continued through all historic ages, and is yet employed, more or less, in every quarter of |