COMMERCIAL STATISTICS. Exhibit of business done in the year 1879 at Grand Marais, Cook County, Minnesota. SURVEY OF SUPERIOR BAY, TO DETERMINE THE BEST AND MOST ECONOMICAL PLAN FOR HARBOR IMPROVEMENT FOR THE HEAD OF LAKE SUPERIOR. ENGINEER OFFICE, U. S. ARMY, Saint Paul, Minn., April 5, 1880. GENERAL: I have the honor to present the following report of a survey of the Bay of Superior, made in accordance with the provisions of section 2 of an act of Congress approved March 3, 1879, the provision reading as follows: Superior Bay, to determine the best and most economical plan for harbor improvement for the head of Lake Superior. The party for the survey was organized early in August, as soon as possible after the appropriations had been rendered available. The field operations consisted substantially in the necessary triangulation connecting with the base-line of the lake survey; in meanders, soundings, both within and without the bay; cross-sections of Minnesota and Wisconsin points, and hourly gauge readings, and verifications of bench-marks; in fact, all data that could be accumulated for the construction of a comparative map. The soundings, especially, are numerous; less than onehalf of them appear on the tracing herewith. The maps of 1861 and 1873, of this bay, are the ones made use of for comparison with the map of the survey just closed. The history of the bay and its improvements has been so fully delineated in previous printed reports by my predecessors and myself that it does not seem necessary here to more than refer to it. The ports of Superior City and Duluth are contained in the Bay of Superior, although separated from each other by a dike built in 1871 and 1872, and extend ing across the bay from Rice's Point to Minnesota Point, the dike having been built by the city of Duluth as a compromise measure resulting from the protest of the State of Wisconsin against opening the Duluth Canal, the object of the dike being to prevent the diversion of the waters of the Saint Louis River into the canal and from the Natural Entry. Contours, referred to the low-water of 1873 projected upon the map, show that but little change has taken place in the outer shore line of Minnesota Point since 1861, and that, if anything, it has moved a little seaward since that date. The contrary is manifested by the inner shore line of Minnesota Point, which appears to have been in places eroded considerably, the erosion probably due to change in the direction of the current following the construction of the Duluth Canal. Much of the point, especially near the dike, consists of floating bog. No marked changes are observable in the outer beach. A mean of 1,040 soundings taken in 1873, covering a strip of lake from the Natural Entry to the Duluth Canal, 1,500 feet in width, is 13.704 feet, while a mean of 1,924 soundings, taken over the same area in 1879, is 13.646 feet. As to the changes of depth within the bay, Assistant Frizell, whose report is herewith, says: As to the depths within the bay, the accord between this and the survey of 1873 is less satisfactory. A mean of 4,408 soundings taken in 1873 gives 8,524 feet. A mean of 4,390 soundings on the same ground taken in 1879, gives 8,017 feet, showing an apparent decrease of depth of 0.507 foot since 1873. I am unable to account for any such extensive shoaling as this result would indicate, and am strongly inclined to ascribe it to an error in the survey of 1873, more especially as I find that the assistant, who made the special survey of the preceding year, was perplexed to account for a deepening showed by his survey as compared with that of 1861. I find no record of any discrepancy between the surveys of 1872 and 1873, and if there was an error in the gauges or bench-marks of the former it was probably repeated in the latter. The mean of 561 soundings, taken in 1861 on the same area, reduced to the plane of the present survey, is 7.46. The soundings of 1861 are recorded in full feet without fractions. As it is not probable that any sounding would have been recorded too great (which would mislead navigators), we must assume that the fractional part of every sounding was rejected. This makes the average depth foot too small. The true average depth for 1861 was, therefore, 7.96, which is in substantial agreement with the present survey. The agreement of the soundings outside the harbor indicates that the error, if such it be, does not extend to the two channels of entrance. The most important fact brought out by the survey is the extent of the scouring action in the Duluth Canal, and the increased depth; and the reverse, to a certain extent, at the Entry. The map of 1873 shows an average depth through the Entry of 13.36 feet, and throughout the canal of 15.59 feet. The present survey shows throughout the Entry an average depth of 12.6 feet, the canal showing 19.4 feet The scouring action in these channels is due to two causes: 1st, the constantly recurring oscillations of the lake surface, causing both inward and outward currents of considerable velocity through the channels; 2d, the volumes of the Saint Louis and Nemadji rivers, both of which before the opening of the Duluth Canal found egress to the lake through the Natural Entry. The dike above referred to, flimsily built, has settled out of sight, and large portions of it have been carried away by waves. It is, at present, but a drowned dam of irregular profile, and with large apertures for the passage of water. The extent of its settling will be appreciated when we consider that it was constructed to completely separate the harbors of Duluth and Superior and prevent the diversion of any of the discharge of the Saint Louis River towards the canal, and that at present a section taken along its axis shows an area of 21,600 square feet of water-way, the length of the dike being about 5,000 feet. The distance from the mouth of the Saint Louis River to the mouth of the canal is 11,900 feet, while to the mouth of the Entry it is 27,000 feet. The cana. is 1,200 feet long; the length of the Entry, 2,600 feet. The average width of the former is 250 feet, and of the latter, 350 feet. The average cross-section of the canal is, at present, 4,850 square feet; that at the Entry, 4,410 square feet; soundings all referred to the plane of low-water of the winter of 1873. It will be seen that the resistances to the flow of water through the canal are less than at the Entry. Of a large number of floats placed in the Saint Louis River just above its mouth, a number moved towards the dike, and would have, if they had not been picked up, entered the canal. The conclusion can hardly be avoided that the opening of the canal and failure to keep the dike in order has caused some deterioration of the channel through the Natural Entry. That there is a movement of the soft material of the bottom of the bay due to scouring and wave action, and to material brought down. the Saint Louis and Nemadji rivers, is undeniable. It has frequently been found necessary to retouch areas that had been previously dredged over to the full depth required. The act of Congress refers to the best and most economical plan for harbor improvement at the head of Lake Superior to be deduced from the results of the survey. The map from the survey is very complete, and affords basis for estimate for any plan proposed. But before any radical change of plan can be entertained the necessity, expediency, or advantage of such change must be demonstrated by existing commercial interests, lines of wharves, &c., or by at least sufficient surety of the immediate development of such as to put them out of the range of the prospective. There seems little doubt that before long the value of Duluth and Superior City as shipping ports will be largely increased. The present plan of improvement consists in dredging in the harbor of Duluth in the vicinity of the docks, and the excavation, by dredging, of an anchorage ground to the east of the canal, the dredging to be 16 feet below the low-water of 1873, and such repairs to the piers as may be absolutely necessary; and for the harbor of Superior City, repairs to the piers and preservation of weak points upon Minnesota and Wisconsin Points. Last season a small channel 10 feet in depth was dredged on a line past Rice's and Connor's Points connecting the two harbors. From the location and direction of the Duluth Canal vessels have not found, during storms, perfect safety in lying at the wharves. The anchorage area now being excavated will admit, when finished, of better protection to vessels under the lee of the point. (See map.) But this question of protection to vessels at anchor is receiving, in large part, its solution in the inauguration last year of a series of private slips normal in direction of length to the general dock lines. The possibilities of the entire bay for harborage are great, as a glance at the map will show. Probably the time is not far distant when the greater part of the western and southern perimeter of the bay will be faced with docks and wharves, and a large portion also of Minnesota Point. Whenever such obtains, dredging on an extensive scale, and probably on lines parallel to the lines of wharves, will be required, and an assured channel of communication between Duluth and Superior Cities, within the bay, instead of by the outside passage. As it is, but one small vessel of light draught entered the port of Superior last season. Various plans have been suggested at times by interested parties, viz, to close up the Duluth Canal and excavate another one about 2 miles farther down Minnesota Point at a point directly opposite the mouth of the Saint Louis River; another, to have three openings instead of the two now existing; a third, to close up both the canal and the Entry and excavate the new channel across Minnesota Point above referred to, also to remove the greater part of the dike, &c.; but in the absence of positive information as to immediate increased wants of commerce, I do not think that any great change from the present plan can be recommended, or even discussed. Accompanying are statistics of the ports of Duluth and Superior, including list of dates of opening and closing of navigation at Duluth since 1855; table giving force and direction of prevailing winds during 1877, 1878, and 1879, from records of the United States Signal Office; report of Assistant J. P. Frizell; also, two tracings, and one plotting of hourly gauge-readings taken during the survey. Very respectfully, your obedient servant, Brig. Gen. H. G. WRIGHT, Chief of Engineers, U. S. A. CHAS. J. ALLEN, Captain of Engineers. COMMERCIAL STATISTICS. In the Bay of Superior are included the harbors of Duluth and Superior. The harbor of Duluth, Minnesota, is in the collection district of Duluth. Duluth, Minn., is the nearest port of entry. The collections for the year 1879 amounted to $5,683.12. The harbor of Superior, Wis., is in the collection district of Superior. There were no arrivals or departures of vessels at this port during the year 1879. Marquette, Mich., is the port of entry, at which place there was collected the sum of $10,331.95 for the fiscal year ending June 30, 1879. |