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exceed ten times its probable annual net revenue. This probable revenue when the canal is completed, and the irrigable area all watered and cultivated, is estimated at a sum exceeding two millions of dollars per annum.

The interests intended to be developed by the Act will be most promoted by embracing within the area to be made irrigable from the canal the largest quantity of land possible, without increasing the cost of construction so much as to increase the rate to be charged for water for irrigation. This will require a high level and a large canal. Smooth and level land offers the cheapest route; placing it upon steep slopes increases the cost of constructing the canal. The rim of the plain to be irrigated is so irregular in height at its intersection with the foot-bills, that if the canal is confined to smooth land it will exclude a large body of land that needs irrigation and may be made valuable with it. Includ. ing too large an area for irrigation, on the other hand, will place the route so much in the bills as to swell the cost of the canal and raise the price of water over the whole area. I took much pains to find the line between the two. The difference between the cost of large and small canals upon the same ground is not as great as the respective capacities for delivering water, and when there is need of it, the large canal is the cheaper, and can supply water at a lower rate than the small one. The counties before mentioned contain a million of acres of land that would be improved by irrigation. About three fourths of that quantity is included in the area irrigable from the route surveyed. It requires a canal of one hundred and eighty feet wide on the bottom and ten feet depth of water at the head, and a supply of six thousand seven hundred and forty cubic feet per second.

To diminish the cost of constructing the main stem in the side bill work below Stony Creek, a branch canal forty three miles long, ending at the head of Sycamore Slough, has been planned and estimated. It will relieve the main stem of one thousand one hundred and eighty-three cubic feet of water per second, and irrigate one hundred and forty thousand eight hundred acres of land.

The prosperity of the irrigated region will depend upon regularity and certainty of supply, and tbrough these upon the security of the canal. The dependence will increase with time and growing population. The location and plan of the canal should therefore be carefully adapted to the future wants of the irrigable region; and all parts of it which cannot be renewed without suspending the use of the canal, should be substantially and permanently constructed.

The route surveyed is for a canal one hundred and seventy-eight and a half miles in length. An extension to Suisun City from the one hundred and sixty-sixth mile, instead of the line to the Cache Creek Slough, is advised. It will increase the length to about one hundred and ninety miles. The plan based upon the survey and proposed extension is for a canal of capacity to irrigate seven hundred and eigbty-two thousand acres of land, with full supply of water from the Sacramento River; the work to be substantial and permanent in most particulars. The estimate is based upon present prices of work and present facilities for doing it, immediate construction to the full size, complete for navigation as well as irrigation, and capable of satisfying all the demands that may be made upon it by a dense population.

The drainage of Putah, Cache, and Stony Creeks is shown, and their capacity to furnish a partial supply of water. If found practicable to introduce it, (and surveys are advised to test the question,) it will reduce the width of the canal, as now planned, equal to one third, and its estimated cost probably one fourth. It would supply irrigation to more than four fifths of the area irrigable from the canal, at an outlay of less than half of the estimated cost of the canal complete for both irrigation and navigation, and render unnecessary for purposes of irrigation the early construction of the more expensive parts, viz: thirty-six and a half miles above and including Stony Creek, the twenty-two miles above and including Cache Creek, the connection with tide, four masonry aqueducts, and all the locks and flumes, which may be postponed until needed for navigation.

The building of the link between Cache Creek and Suisun to the full size required, if supply of water from Cache and Putah Creeks is found to be practicable, is proposed. It will irrigate more that two hundred and seventy-five thousand acres of land. Neglecting for the present the connection with tide water for navigation, and the twenty-two miles next above and including Cache Creek, the building of the eighty-five miles between the one hundred and twenty-first mile and Stony Creek, and the forty-three miles of branch canal, is also proposed; the supply of water to be drawn from Stony Creek at first." And preliminary to this, in order to provide a partial irrigation to cheapen the cost of subsistence and forage, reduce the cost of transporting materials for building, and to supply water for domestic purposes, the construction of a small canal is suggested, with the condition that it be placed on the right ground for the large canal, and be so constructed as to admit of enlargement without unnecessary cost. The outlay required to build such a temporary work, it was not thought necessary to estimate.

The fifty-eight and å half miles of the canal, which embrace the first thirty-six and a balf miles from the head, and twenty-two miles between the one hundred and twenty-first mile and the right bank of Cache Creek, will together irrigate one hundred and twenty-seven thousand nine hundred and twenty acres of land.

The one hundred and thirty miles wbich embrace eighty-four and a balf miles next below Stony Creek, and forty-five and a half miles next below Cache Creek, with the addition of forty-three miles of branch canal, will irrigate six hundred and fifty-four thousand and eighty acres of land.

The parts composing the fifty-eight and a half miles are necessary to a canal complete for navigation, and for a perfect watering of the wbole

a irrigable area. They will be necessary for irrigation generally, if supplies of water cannot be drawn from Putah, Cache, and Stony Creeks; but with sufficient feed from them, the construction of these parts may be postponed until they are required for navigation, and the building of the other links containing one hundred and thirty miles of main stem, and forty-three miles of branch canal, will irrigate six hundred and fiftyfour thousand and eighty acres, or more than four fifths of the whole irrigable area.

The estimated cost of these divisions of the canal is as follows:

For a canal complete for irrigation and navigation, substantially and permanently built, capable of receiving and distributing six thousand seven bundred and forty cubic feet of water per second, and the full supply to be drawn from the Sacramento River:

$6,550,015

$4,831,053

For the 584 miles, to irrigate 127,920 acres......
For the 130 miles of main stem, with 43 miles of branch canal, to irri-

gate 654,080 acres..........
Work on the latter not necessary until the whole canal is built, and
which may be postponed-deduct from one and add to the other....

Making the estimated cost of the respective parts .....

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The smaller sum includes four hundred and eighty-one thousand five hundred and seventy-seven dollars for an aqueduct of masonry over Putah Creek.

The canal is eighty feet on the one hundred and twenty-first mile and exceeding one hundred and thirty feet on the thirty-sixth mile wider than will be necessary for irrigation, if a quantity of water is drawn from the three creeks before named equal to their capacity to supply. Making this reduction, the saving will be very large, particularly in the width and cost of the five great aqueducts. Opportunity was not afforded to me to collect the information necessary to make even an approximate estimate of the cost of reservoirs and canals upon the creeks, necessary for the purpose. It is plain, however, that if a large portion of the drainage of the creeks is reserved in the mountains, that the length of the three largest aqueducts may be reduced in proportion -perhaps large culverts be substituted for them—and their cost, estimated at more than three millions of dollars, be reduced to a small sum.

The plan and estimate of the canal embrace one large basin, with gaard bank, guard lock, and feeder, at the head; one hundred and ninety miles of main stem, with one bundred and eighty culverts, five large aqueducts, fifteen lift locks and flumes around them, one tide lock, and twenty-nine overfalls, all of masonry; one hundred and ninety sluices for distributing water; thirty-one bridges; a branch canal, forty-three miles long, with its crossings and sluices; and fifteen thousand eight hundred and seventy acres of land, besides land drainages estimated in gross.

The climate of California is alone sufficient to attract a large population. Her mineral resources, and the commercial advantages of her position, will insure it. It may become dense in the vicinity of her cities and in the valleys of her great rivers. Insufficient rain for successful agriculture is the rule rather than the exception. Irrigation will become a necessity, and system in establishing the great lines to be built for the purpose is essential to their economical construction and use, and to the prosperity of the State, commercial as well as agricultural.

Appended are some notes in explanation of the different class of work entering into the estimates, of which written plans and specifications have been prepared.

Detached is ove map on a scale of six miles to one inch, and four photograph copies;

One set of twenty-four small maps upon a scale of one mile to two inches;

One set of profiles in twelve sheets, showing the elevation and variation of the ground at the centre line, and at the outer slopes of the canal on the right and left;

Photograph copies of the large map, tracings of the set of small ones, and written copies of the other papers, have been prepared for the President of the Sacramento Irrigation and Navigation Canal Company.

The field-books of the survey, twenty-one in number, are returned with the report.

The formulas employed in the calculations of the flow of water, are those of D’Aubuisson, translated by Bennett.

I was assisted by Mr. James H. Hoadley and Mr. J. R. Ray. To their industry in the field and office, I am indebted to the successful prosecution of the survey, and the details of the estimates. Respectfully submitted,

WM. H. BRYAN,

Engineer in charge of the Survey. SAN FRANCISCO, February 11th, 1867.

NOTES

In reference to and in explanation of the different classes of work entering into the estimate, and of which written plans and specifications have been prepared.

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Works denominated "accessory” in the estimate of the basin, are of a class admitting of only approximate specification or estimate until further surveys are made. They consist of an excavation to receive and pass the low water flow of the Sacramento River; a temporary dam to turn the water into the new channel ; a protection of timber, brush, and rock, upon the right bank of the new water way, to prevent undermining by the river; and a probable use of rock at a few points in its bed to prevent its wearing too deep. Heavy rock for this work, and for

, the rock dike and rip-rap protection to the guard bank at the points of crossing in the sloughs and river, can be obtained in sufficient quantity and at moderate cost in the Iron Cañon, a few miles above Red Bluffs. A large quantity of loose stone lying near the site of the guard bank, may, with advantage to the bank, be cheaply spread upon its inner slope.

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There

may

be

a pressure of water against the head of the guard lock and feeder exceeding twenty feet. As no rock will be found for the foundation, it will be placed upon earth, the quality of which at the site of the lock and feeder appears to be such that the foundation can be made safe. But great procaution must be taken in the quality of the work as well as in the weight of the walls, to make the head works secure.

The plan and specifications of the guard lock and feeder will be found with those of lift locks.

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The line surveyed for the canal may be straightened and shortened at many points with advantage and economy. Generally, however, in passing over elevations upon the plain, they will be found such that an excavation in excess of the quantity needed for the bank opposite to it would require a transportation too great for economy, and the excess would be waste. It is better, in many cases, to procure the material required for embankment, in part at least, from the inlets and outlets of culverts, and from side drains placed at least twenty feet from the foot of the outer slope of the banks of the canal, and having the same slope. In building a canal as wide as the one proposed, there is no objection to placing more of it above than in the ground; loss of water by filtration is less in good embankments than in natural soil. Along side bill work the excavation should be no more than is necessary to provide the required water way, to make the bank opposite, and supply the deficiency adjacent to its ends with moderate transportation. Upon a plain, with choice of ground for a canal of two banks, and with an allowance of

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