not generally recognized. After a while there comes a time when vessels touch where they have been accustomed to have fathoms of extra depth below them. Then the condition becomes evident, and the wonder is that so bad a result could have grown up in the dark, without observation of any person. The only safe system is one that discovers from time to time the actual condition and compares it with the condition found two or three years before. If harm is in progress, the fact is known and the measure of its growth is determined. Opportunity is afforded to correct injurious practice before the evil becomes undue. If it can be demonstrated that depositing mud in channels has impaired their value and depth, it is to be supposed that the State authorities will take up an alternative method of disposing of the spoil. Fortunately there is a large area of marsh and low land moderately convenient to the shores of the bay and near the city that can be the receptacle of mud for some years to come. The subject of depositing ashore has been brought to the attention of the Board of State Harbor Commissioners in a letter addressed to the chief engineer, a copy of which is appended. No action has yet been taken. The action of private parties may be expected to conform to the practice of public authorities. Perhaps legislation may be necessary to secure results. With a proper presentation of facts showing injury, and the practicability of a different and harmless method of disposing of spoil, it is to be presumed that appropriate legislation would follow. The foregoing considerations seem to justify the request that an appropriation be asked of Congress for the purposes of investigation. A comparatively small sum may be sufficient to demonstrate whether a larger sum is necessary. It is therefore recommended that $5,000 be asked. I am, very respectfully, your obedient servant, G. H. MENDELL, Lieut. Col., Corps of Engineers. The CHIEF OF ENGINEERS, U. S. A. LETTER OF LIEUTENANT-COLONEL G. H. MENDELL, CORPS OF ENGINEERS, TO THE CHIEF ENGINEER OF THE BOARD OF STATE HARBOR COMMISSIONERS. UNITED STATES ENGINEER OFFICE, San Francisco, Cal., March 11, 1884. SIR: It has been the practice for many years to deposit in the bay the mud dredged from wharves in and near San Francisco, and that dredged from channels in its vicinity undergoing improvement. The latter work, that of improving channels, has been done under my direction. I was early convinced of the impolicy of using the bay as a place of deposit, and soon began to encourage deposit upon land, where the mud could exercise no injurious influence, direct or indirect, upon navigable waters. By degrees the new system of deposit was brought into action in contracts, and now, by various appliances suited to different circumstances, mud dredged in Oakland, Petaluma, and in waters near Stockton is no longer deposited in or near channels, but is placed on shore above high-water mark. Experience and improvements in appliances now enable this very desirable result to be attained at reasonable cost, not much greater than that of the old system of depositing from scows. Under the orders of the War Department and the requirements of a resolution of a former House of Representatives, I have now in hand an investigation of the causes tending to affect unfavorably the commercial value of this harbor by the reduction of the depth of its channels. I am awaiting money to enable me to continue the inquiry, which may include the operations of your works so far as they relate to making the bay a place of deposit for dredged material. Whether or not any measura ble injury shall in this way be demonstrated, you, I feel confident, will agree with me in thinking that the tendency of the present system is unfavorable. Under all these circumstances, it appears to me to be appropriate and in the interest of the General Government, of the State, and of commerce that the subject of landing dredged mud ashore should be taken into consideration by all official bodies having this kind of responsibility. The position of the State in regard to the subject is so favorable in owning low lands adjacent to the water front, very suitable as places of deposit, that I cannot doubt that the Board will recognize the advantages and the propriety of action when the subject is presented to them, and if your opinions shall agree with those here expressed, I beg that you will bring the matter before them. I am, very respectfully, your obedient servant, MARSDEN MANSON, G. H. MENDELL, Lieut. Col., Corps of Engineers. Civil Engineer, Chief Engineer Board of State Harbor Commissioners. O O 2. IMPROVEMENT OF WILMINGTON HARBOR, CALIFORNIA. Reference is made to the accompanying report of Assistant Engineer A. Boschke, for details of operations during the past year. The channel over the entrance bar has recovered the foot in depth stated to be lost in the last report, making again 10 feet at mean low water. The disturbances of the interior channels caused by the obstruc. · tions of the railroad wharf and the wreck Adelaide Cooper have been composed, and the normal action of tidal forces have been restored in reshaped channels. The accumulation of sand on the outer bar has, however, merely changed shape and place of deposit, and has not been diminished. The opinion was expressed in the last report that 10 feet at low water is about the limit of depth to be expected from natural action. There seems no present reason for change of opinion. It will, therefore, be necessary to gain increased depth by dredging. The estimate of dredg ing necessary to give a width of 320 feet and 16 feet depth over the bar, reduced to 200 feet width inside of the bar, is 129,400 cubic yards of sand. This is the minimum amount of dredging that will have to be done. To give the channel its proper form and dimensions requires something over 200,000 yards, measured in place. This work ought to go in hand with the raising of both jetties and extension of the west jetty, but with the funds supplied to the work it is impossible to carry on the operations in the way engineering principles require. It necessarily follows from this condition that the improvement cannot be carried on in the most economical way, and that estimates must necessarily be exceeded. During the year the channel through the reef was completed, not to the full width of 350 feet, as contemplated, but to the extent that the funds permitted. There is now an opening through the reef 320 feet in width, over 280 feet of which the mean low-water depth is 16 feet and over the remainder 15 feet. The length of this cut averages 880 feet. The amount dredged during the year was 11,851 cubic yards. It was a disappointment to find the reef material unsuitable for use in extension of the west jetty. The accretion of sand on the seaward side of the main jetty, which in 1876 and in several years following had redeemed from the sea 40 acres of land covered with sand dunes bearing the usual beach vegetation, and had extended protection to the timber-work for a half mile or more of length, has suffered diminution during the past year or two. Several hundred feet of the timber-work, not now in the best condition, have been exposed. This action gives rise to some uneasiness as to the stability of a portion of the jetty, and may, if not reversed, in the natural cycle of change in deposit and abrasions require special construction to counteract its influence. This result could not be foreseen, and it will probably add to the necessary cost of the harbor. Some interesting studies of currents, their velocities and directions, supplementing observations of past years, have been made which bear in an important way upon future operations. These are alluded to in the accompanying report. A comparison of early with recent maps shows a disappearance of large areas of land along the shores around the Bay of San Pedro, carried away by waves. As the land is bluff 80 or 100 feet in height, the contribution of sand and other earthy material to the bed and shores of the sea is considerable. It would seem from a general consideration of the subject that this amount of shore degradation is by no means insignificant as a source of ocean sand, compared with the small streams which for two or three months in the year contribute loads due to inland erosion. This subject has a bearing upon the future of the harbor and bay, the measure of which cannot now be recognized. Doubtless the destruction of land and deposit of detritus have already added to the accumulations lying at the entrance of the harbor. The objects to which funds now available and those herein asked are to be applied have been indicated in what precedes to be dredging the sand at and near the entrance, and to raising, extending, and protecting the jetties now existing, with the view of securing and maintaining 14 or 16 feet depth at low water, or 20 to 22 feet at high water. The improvement will then be complete, and it would not be judicious to attempt more. The advantage of an increase from 1 foot, as the harbor was at the beginning of the improvement, to 10 feet, as it is now, is very highly appreciated by a large commerce and population, and if an addition of 4 or 6 feet can be secured the accommodation will be very satisfactory and worth more than the money it may cost. July 1, 1883, amount available Money statement. July 1, 1884, amount expended during fiscal year, exclusive of outstanding liabilities July 1, 1883. July 1, 1884, amount available ... Amount appropriated by act approved July 5, 1884.. Amount available for fiscal year ending June 30, 1885 $29,916 34 29,898 47 17 87 50,000 00 50,017 87 Amount (estimated) required for completion of existing project. 150, 000 00 Amount that can be profitably expended in fiscal year ending June 30, 1886. 150,000 00 REPORT OF MR. A. BOSCHKE, ASSISTANT ENGINEER. UNITED STATES ENGINEER OFFICE, SIR: I have the honor to submit an annual report for the fiscal year ending June 30, 1884, upon the progress of the improvement of Wilmington Harbor and the facts ascertained from surveys and observations made under your directions. In obedience to your instructions of August 25, 1883, I relieved Assistant A. J. Swift on the 5th of September, at that time in charge of the work. The work of dredging the reef across Wilmington Bar, under contract with the Pacific Coast Dredging and Reclamation Company, was in force on July 1, 1883, and progressed favorably until some time in August, when the contractor met with many mishaps, viz, the sinking of the dredge, which caused a delay from August 4 to 21, and the sinking of his tng-boat in September; also the sinking at the dumping ground during that month of one of his dump-scows, which delayed the work in so far that the dredge had to stop work during the dumping of the only remaining dumpSCOW. The weather was also unusually stormy from August to the completion of the work, which often during the work brought undue strain upon his machinery, causing frequent breakage, or compelled the dredge to suspend work during heavy ocean swells. The work was satisfactorily completed on the 14th of December, 1883. From July 1, 1883, 10,569 cubic yards of reef material and 1,282 cubic yards of sand were excavated, making a total under that contract of 37,119 cubic yards of reef material and 3, 152 cubic yards of sand, at a total cost of $90,661.60. None of the material excavated during this year was suitable for the extension of the west training-wall. This amount of dredging has left the reef with a depth of 16 feet at mean low water, 280 feet wide, for an average length of 880 feet; besides, an additional width of 40 feet, about 600 feet, has now a depth of 15 feet at mean low water. Numerous soundings record the present condition of the excavated part of the reef. Cross-sections 10 feet apart, with soundings at intervals of from 4 to 5 feet, were made and mapped upon six sheets, which are hereby respectfully submitted. To complete a continuous channel of 16 feet deep at mean low water 320 feet wide from the entrance of the harbor to the Southern Pacific Railroad wharf, where ship and rail meet, requires dredging of 237,300 cubic yards of sand. If available funds should not permit the completion of a channel with above dimensions, a reduction in width, and even in depth, might be made over the inner bar, but the depth of 16 feet at mean low water should be made over the outer bar, with as great a width west of the 16-foot contour as the funds permit, in order to gain the greatest possible benefit from the expenditure to the usefulness of the harbor. The following estimates show the amount of excavation required for different dimensions of channel: A continuous channel of 16 feet at mean low water, 320 feet wide over the outer bar, but with a width reduced to 200 feet over the inner bar, will require dredging of 129,400 cubic yards of sand. A continuous channel of 16 feet at mean low water, 320 feet wide over the outer bar, but contracted to 200 feet wide and 14 feet deep at mean low water over the inner bar, will require dredging of 85,500 cubic yards. A saving of cost for this dredging would be gained if the material could be put ashore and used in connection with filling flats between the southern end of the Southern Pacific Railroad wharf and the west end of the west training-wall, and bounded by the western edge of the ship-channel to be excavated and the San Pedro shore. In that case the indispensable long tow would be saved and the material also safely disposed of. Further advantages would result therefrom: First, it would confine the west edge of the ship channel to a definite bank, with a gentle curve directing the ebb current under the most favorable circumstances for effective scour to the bar; second, it would give to the Southern Pacific Railroad Company much-needed terminal facilities of room on land and a largely increased wharf front, which both are already needed, but will become indispensable in the near future; third, it would save the Government the cost of raising that part of the west training-wall which would constitute one side of the inclosure of this ground, or about 1,500 feet of wall, which would have to be raised, as soon as available funds permit, to a height of 2 to 3 feet above high water, for the reason that a large amount of sand and detritus from the adjacent wasting bluff is lifted by heavy breakers over that part of the training-wall and distributed over the now existing flat, and from thence is washed by abrading currents into the ship-channel. It is to be hoped that the railroad company will avail itself of this opportunity to secure for filling of this flat the spoils to be dredged from the ship-channel and bar. The map of the survey of the bar and harbor made December, 1883, show the present condition of the bar and ship-channel, with the exception of the constant gradual increase in depth and seaward movement of material since. The changes that have been wrought by the works of the improvement inaugurated twelve years ago are shown upon the plates 3 and 4, representing longitudinal profiles in which the condition of the bar, reef, and channel are shown. First, before any of the improvements had been made; next, after the completion of the breakwater and the two jetties designated No 1. and No. 2; third, the condition at the end of the fiscal year of 1883, and, finally, the condition at the end of the present fiscal year. At the completion of the breakwater, when the tidal currents were confined, a new tidal channel began to be scoured. Referring to plate 3, the bottom represented along the course of deepest water by the yellow line, in 1859, was lowered by tidal scour through nearly the entire length from opposite the initial point of the breakwater to beyond the bar to a depth represented by the blue line, increasing the depth from 1 foot to 4 feet in the fall of 1874, and beginning to assume a definite channel from its former undefined character. In the following year the depth and width of the new channel further increased to give an available channel of 6 feet at mean low water, and vessels of light draught began to enter the harbor. It became, however, apparent that further rapid action of scour had ceased, and it was determined to aid by dredging the formation of a channel 10 feet deep at mean low water. A cut of 400 feet long by 220 feet wide, thence 200 feet long by 120 feet wide, and 10 feet deep at mean low water, was made on the inner bar through sand and along the reef which lies across the ship-channel in the direction from San Pedro Bluff to Deadman's Island. A cut 500 feet long, 60 feet wide, and 10 feet deep at low water was dredged. The dimensions of the channel over the reef were increased by dredging in 1876 and 1877 to 150 wide and 12 feet deep. The accompanying results were a deepening by scour of the channel upon the inner bar at the rate of 1 foot per year, giving a depth of 9 feet at mean low water in 1878, with a well-defined width of about 200 feet and a good alignment. In 1879 the increase on the inner bar from scour only reached 0.5 feet, and dredging was again resorted to. In 1880 the channel over the reef was increased to a width of 235 feet and 12 feet deep at mean low water, and a narrow trench 14 feet deep was dug into the inner bar. Simultaneous with the dredging operations a training-wall on the west side of the channel was built, from time to time extended and raised to 4 feet above mean low water, and the combined results were a steady increase in depth and width of the channel, benefiting the commercial usefulness of the harbor to an extent that, in 1881, the first vessel drawing 16 feet of water could enter. In 1852 the Southern Pacific Railroad Company extended their track to the harbor and built a wharf 1,600 feet long, bringing ship and rail together, which relieved commerce of the former heavy burden of lighterage. With the exception of imported coal, which comes to this port in large ships, all the coasting trade entered the harbor from that time. In 1882 and 1883 the channel over the reef was further widened and deepened to 320 feet and 16 feet at mean low water, removing all the reef material over its entire length. The former wise policy, not to permit the seaward movement of the scoured material to reach the mouth of the harbor any faster than the littoral current passing the entrance from an easterly to a westerly direction could move and keep the mouth of the harbor free from deposit, has, since 1881, when the first wharves were built in the harbor, beyond our control. The rapid increase of population and prosperous development of Los Angeles and Sau Bernandino counties and Arizona and the extension of the Southern Pacific Railroad and its final transcontinental completion, demanded the extension of the railroad to deep water and the building of other wharves along the west shore of the harbor. These structures encroached upon the channel and changed its former regimen, causing large quantities of sand to be scoured from the east shore, and its bottom, which moved with the ebb current rapidly seaward, building up an extensive flat at the mouth of the harbor. The only remedy is the early removal of this material by dredging on such portion which lays in the path of the scouring ebb current. The currents would in the course of time undobtedly wash this material into the approaches of the harbor. The average depth being only 4 fathoms, this action should be guarded against and prevented. In adopting for the first 4,700 feet timber structures in building the breakwater, it was with good reason expected that sand would accumulate on the seaward face forming a continuation of Rattlesnake Island for that distance and build up a permanent barrier between the ocean and the inner harbor. This has been, however, only realized in part. A survey at the close of 1872 shows nearly 20 acres had formed in the extension of the south end of Rattlesnake Island. From that time the accretion made slower progress, for by 1876 only an additional area of 19.5 acres was accumulated. However, the crest of the beach was raised about 2 to 3 feet above high water; dunes formed even to greater heights, and an extensive flat, bare at low water, built out to the line of the double work: All this promised well for the final desired result, to back the entire wood structure by a broad sand-beach raised above the action of the breakers. After 1876 the accretions stopped, or rather oscillated. At times abrasions would take place for a short time, and then the beach would return to its former limit. An attempt was made to assist nature by planting a number of low brush jetties from the outer face of the breakwater upon the low-water flat, and parallel to the line of breakers. For a time they promised well, but when the winter storms and high tides |