[First indorsement.] U. S. ENGINEER OFFICE, Baltimore, Md., September 30, 1891. Respectfully submitted to the Chief of Engineers. Should Congress decide to enter upon this improvement it is recommended that it be on the basis suggested by the United States agent, in his report of September 26, 1891, to the extent of $9,500. Where the total amount involved is so small it is greatly in the direction of economy that the whole sum be available for a single contract to be executed in one operation. WM. P. CRAIGHILL, Colonel, Corps of Engineers. REPORT OF MR. A. STIERLE, ASSISTANT ENGINEER. UNITED STATES ENGINEER OFFICE, SIR: I have the honor to submit herewith a report upon the survey of Rock Hall Harbor, Maryland, and a project for the improvement of the same. For information relating to the benefits to commerce and navigation which would result from the improvement of this harbor I would respectfully refer to the preliminary report submitted on November 20, 1890. The survey was made during the early part of August last. The most prominent points on the shore around the harbor and Chesapeake Bay, south to Huntingfield Point and north to Swan Point, covering all the portion necessary for the project in view, were fixed by a skeleton triangulation, the intermediary shore line being subsequently filled in with the stadia rod. Besides the hydrography of the harbor proper, that of Swan Creek Inlet and across Swan Point Bar due west from the harbor was included as far as the 10-foot depth in the bay. Tidal observations were made for sixteen days on a gauge set in the harbor close by the remnants of an old pier. The average rise and fall of the tide for the sixteen days was found to be 1.10 feet. The greatest range of the tides observed was 2.85 feet, rising 2.22 feet above and falling 0.63 foot below the mean water level. There were no unusually severe meteorological disturbances during the period of observation. The feebleness of the tide is characterized by a long duration of the stands at both high and low water, which in the first case averaged sixty-three and in the latter fifty-six minutes. These, together with the pronounced effects the winds have upon the wide expanse of the bay, causing repeated fluctuations of the water level, though small in magnitude, made it difficult to obtain by simple board-readings the exact time of the middle of the high and low water stands and the mean duration of the flood, which was calculated to be four hours and forty-eight minutes, and that of the ebb, which was determined in the same manner as six hours and forty-eight minntes, can not, therefore, be accepted as very accurate. In comparing the hydrographic results of the survey with the configuration of the bottom, as given on the Coast Survey chart dating back to probably 1845-the only map available for comparison-there is very little change to be noted as having taken place since that year. The soundings of the present survey give, with the exception of that portion immediately around Swan Point, a slightly increased depth of water everywhere. This may be principally due to the adoption of a different plane of mean low water in both surveys to which soundings were reduced. At any rate it is safe to assume that within the past fifty years the depth of water of this locality has remained unchanged. There are no indications of any decided accretion in the existing shoals, nor any marked increase or decrease in depth within existing channels. The absence of the generally prevailing tendency in littoral currents to fill up gradually any indentation in the shore line is the more remarkable in the case of Rock Hall Harbor, since the latter, a mere small bight in the shore and devoid of any currents, appears to possess all the characteristics required for its own destruction in the direction indicated. This is, however, with few exceptions, no unusual phenomenon in the smaller prongs of the eastern shore of the Chesapeake Bay, and since, as stated in the preliminary report, Rock Hall Harbor, small as it is, was quite a prominent landingplace one hundred years ago, and has lost since that time none of its qualities that made it desirable for that purpose, it may be inferred that the contemplated improvements, when made, will be permanent for a long time to come. In conformity with the desire expressed by those interested to establish a landing for large vessels in Rock Hall Harbor which would be nearer the town than the present landing in Swan Creek, a channel 100 feet wide and 10 feet deep at mean low water has been estimated for, and is here with presented as a project of improvement. This channel is to extend from the 10-foot depth in Swan Creek Inlet to about the site of the former old pier in the harbor. The total length of the cut is about 5,650 feet. The bottom is principally soft and sticky blue mud. It is supposed that the proposed depth of 10 feet is ample for the largest bay steamers and for the larger class of sailing vessels. The remaining area of the harbor can be used, as now, by the smaller fishing and oyster boats. It remains to refer to the desired channel across Swan Point Bar, of which mention is made in the latter part of the preliminary report. The results of the survey show that the general conditions for dredging such a cut are not as favorable as was previously anticipated. A subsidiary channel across the bar could not be found, but there are several slight depressions about 6 inches lower than the average depth over the crest, which is 2 feet below mean low water. The survey has further developed the fact that Swan Point is now much farther south of its location in 1845, and that it has grown since that year in an almost due southerly direction a distance of about 1,100 feet. As was previously stated, this is the only change noted in comparing the present chart with that of the Coast Survey of older date. It can not be said whether this growth is a periodical or a gradual one, nor can it be foretold with any degree of certainty when and where it will reach its limit of extension. It is sufficient to record that at present its annual movement southward is about 24 feet, and that it may eventually reach, if not arrested by artificial works, any cut made across Swan Point Bar. For the sake of direction only, the proposed cut, as shown on the accompanying chart, is located in range with the Brewerton Channel, leading out of the mouth of the Patapsco River, on the opposite side of the bay. It is of little consequence which direction across the bar is adopted, as in any event no currents prevail here that can be depended upon to keep a dredged channal open, whether the cut is artificially inclosed or not. The frequent passage of vessels, particularly of steamers, would perhaps do more to prevent it from filling up again than anything else that could be devised. The length of this cut as proposed is about 1 mile. Its width and depth are the same as proposed for the harbor proper, viz, 100 feet and 10 feet, respectively. The distance between Baltimore and this portion of the Kent County shore would be reduced nearly 9 miles by this channel, and not only Rock Hall, but other landings on the adjacent shore, would be benefited if it were made. This portion of the project is, however, only indirectly related to the improvement of Rock Hall Harbor, and the estimate is herewith given parenthetically, and is: 80,000 cubic yards of dredging, at 20 cents per cubic yard; total cost, $16,000. The proposed project for the improvement of Rock Hall Harbor is a channel 100 feet wide and 10 feet deep at mean low water from the channel in Swan Creek Inlet to the old pier in the harbor. The estimate is: 47,565 cubic yards of dredging, at 20 cents per cubic yard, $9,513. Very respectfully, your obedient servant, Gen. WM. F. SMITH, A. STIERLE, Assistant Engineer. United States Agent. |