of hydraulic carriage, which has the merit of cheapness, but which necessarily floods the lands and distributes the material over them. Placing dredging at 50 cents, the estimate becomes, for a 4-foot channel SIR: I have the honor to submit the following report on the results obtained during the survey of Napa River, made under your direction. The survey was commenced at a point near the Vernon Mills, a short distance above the present railroad crossing at Napa City. Thence the work proceeded down river to a point at the head of Bull Island, including a total distance of some 40,000 feet, linear, or, say, 1.75 miles below the Suscol Ferry. Three tide-gauges were in use for the hydrographic work-one at Napa City, one at the asylum wharf, and the third at the wharf at Suscol Ferry. The zero marks of each gauge were connected with suitable bench-marks established near by, and the whole systein connected by a line of levels carried down river along the east bank. The low water adopted for the reduction of soundings on this survey was taken or assumed at an elevation of 1.7 feet below the low-water reading observed on the Napa City gauge on the evening of December 11. This low water, by estimation from the Oakland Harbor gauge reading of that date and time, reduced to the Coast Survey low water, was 1.50 feet above low water. Also, since the low-water tidal constant for Mare Island is +0.2 it follows that the predicted low-water elevation at mouth of Napa River was at that time 1.7 feet above Coast Survey low water. In setting the gauge at Napa City it just so happened that the low-water reading of December 11 was found to be also 1.7 feet, hence the zero of this gauge was adopted as low water for Napa City and vicinity. By the gange at the asylum wharf it was ascertained that the corresponding low water was 0.08 foot below that at Napa City, and, lastly, it was also ascertained that the same plane at Suscol Ferry gauge was 0.30 feet below that at Napa City. Wing-dams.-As regards the possibility of improving the navigable channel by constructions, I would state that as far as my observations extended I saw no place where artificial construction could be applied with any marked advantage. The river channel as a rule is narrow and the banks quite bluff, and where shoal-water bars do exist, there seems to be no corresponding increase in width between adjoining high-water banks. Dredging work.-There seems to be little or no question about the fact that the most feasible and effective plan of alleviating the present needs of navigation is by dredging out channel-ways through the shoal-water bars, the material of which is mostly coarse gravel and sand. The asiest and best place to deposit the excavated material would be on the adjoining banks. In regard to obtaining permission of land owners for the right to such disposal, I would state that the matter has been taken in charge by the city attorney of Napa, who will call a meeting of the riparian proprietors and discuss the entire subject, after which they will franie a document for general signature stating what they would be willing to do in the matter. This document will be forwarded to the office as soon as practicable. Lone Tree Reef.-This obstruction was examined with care. It proves to be much more formidable than I had reason to expect from reports of the river men. In brief, the obstruction may be described as follows: The reef is due to the encroachment of a "spur" or low ridge coming down from the foot-hills on the east. The difficulty here consists in a dangerous shoal-water bench, which occurs in the middle of the bend and along the concave bank. This bench projects out in places 60 feet from low-water line and is covered 1 to 2 feet of water at low tide; thence across to the westerly bank the depths are generally ample for all present or future needs of navigation. This submerged bluff bank extends up and down stream a distance of about 300 feet, and is therefore a formidable obstruction to remove. The material of this reef is argillo, calcareous sandstone, considerably disintegrated. A sample is herewith submitted. While the examination was going on a new discovery was made in the form of a point of rocks, located in the channel next to the point, which is now being used for navigation. These points of rocks or stumps," so called from their similarity in form, were found to exist at a point distant about 50 feet from the west bank. There was a depth of only 1.5 to 2 feet at low water on top of these stumps, while immediately around it there was fully 6 feet water at the same stage of tide. 66 As to the question of improving this reef, I am of the opinion that the only practicable way to do so would be to simply remove the points of rocks by surface blasting, and thus clear the point channel now in use. Sailing vessels have frequently hit these "stumps" and carried away their rudders. Snags. The low tides in Napa River did not occur at times which permitted me to thoroughly examine the channel with the view of counting the number of snags in the way of free and safe navigation. By combining those which I did see with those noted on the river charts by the pilots, I was enabled to enumerate about thirty snags and hanging trees. Their approximate position is shown on the accompanying river chart used during the examinational survey. Jack's Bend.-This is a sharp bend, with narrow channel-way, distant about threequarters of a mile below Napa City. The proposition to make a cut-off at this place is impracticable. The land on the point is all improved property and cannot be ob tained at a reasonable price. I do not think it feasible to do anything here which will be of any assistance to navigation in this connection. Carr's Bend. This is the first sharp bend above Lone Tree Bend. The high land on the point is cultivated land up to within 350 feet of the point. This 350 feet next the point is low-tide land mostly, subject to overflow at high tide. This portion is newly-made land, and of little or no present value. The steamers have trouble in rounding this bend, particularly when sailing vessels happen to meet them at this place. It is possible that temporary relief may be obtained here by cutting off the tule point. This work would involve the excavation and removal of some 9,500 cubic yards of material. In conclusion, I would state that a pile structure, offering considerable obstruction to navigation, is reported to exist near the mouth of Napa River; it is the site of an old railroad bridge. The center pier should be removed. Commercial statistics for Napa City are herewith inclosed. Very respectfully, &c., Col. G. H. MENDELL, Corps of Engineers, U. S. A. L. J. LE CONTE, C. E., ESTIMATE OF THE YEARLY COMMERCE OF NAPA RIVER, FURNISHED BY W. H. WULFF, OF NAPA CITY. Two steamers (the Caroline and Emma) discharge at the Napa wharves, freight tons.. 20,800 gallons.. 1,500,000 Miscellaneous, consisting of fruit, produce, and general freight....tons.. 2,000 APPENDIX Q Q. IMPROVEMENT OF THE HARBOR AT SAN DIEGO, CALIFORNIA. REPORT OF COLONEL C. SEAFORTH STEWART, CORPS OF ENGINEERS, OFFICER IN charge, for the fiscAL YEAR ENDING JUNE 30, 1885. SAN FRANCISCO, CAL., July 8, 1885. SIR: I have the honor to forward herewith the annual report for the year ending June 30, 1885, of the river and harbor work in my charge. Very respectfully, your obedient servant, C. SEAFORTH STEWART, The CHIEF OF ENGINEERS, U. S. A. IMPROVEMENT OF THE HARBOR AT SAN DIEGO, CALIFORNIA. No repairs were made to the levee in 1884, on account of the high stage of the San Diego River, due to the unprecedented rainfall and floods of the winter 1883-'84. The water continued to flow throughout the latter year, an unusual thing, not sinking until the present summer. The rainfall for this fiscal year has been 8.65 inches, nearly the aver age. Of this amount all but 3 inches fell before January. In that month the damage to the embankment of the levee and to its stone facing caused, during the two past years, by the wash of surface water, by the burrowing of badgers, and by cattle following trails which lead across the work to water and to pasturage, has been made good. The cost of work done has been $78. With the exception of some slight injury since January, due to cattle and badgers, the levee is in good condition. This work is in the collection district of San Diego. That town is the nearest port of entry. Point Loma Light is the nearest light-house. The nearest fort is that begun at Ballast Point. The amount of revenue collected at San Diego during the fiscal year ending June 30,1885, is reported as $5,741.49. Money statement. July 1, 1884, amount available... July 1, 1885, amount expended during fiscal year, exclusive of outstauding liabilities July 1, 1884.. July 1, 1885, amount available $627 50 78 00 549 50 |