Between Lakes Huron and Erie lies Lake St. Clair, a shallow sheet of water, some twenty miles in length, through which all the trade of the Upper Lakes is obliged to pass. At the mouth of the river which connects this lake with Huron, there is a delta of mud flats, with numerous channels, which in their deepest parts have not more than ten feet of water, and would be utterly impassable, were not the bottom of a soft and yielding mud, which permits the passage of vessels through it, under the impulse of steam or a strong wind.
Mr. James L. Barton, a gentleman long connected with the lake-commerce, thus wrote some years ago upon this subject to the Hon. Robert McClelland, then chairman of the House Committee on Commerce:—
"These difficulties are vastly increased from the almost impassable condition of the flats in Lake St. Clair. Here steamboats and vessels are daily compelled in all weather to lie fast aground, and shift their cargoes, passengers, and luggage into lighters, exposing life, health, and property to great hazard, and then by extraordinary heaving and hauling are enabled to get over. Indeed, so bad has this passage become, that one of the largest steamboats, after lying two or three days on these flats, everything taken from her into lighters, was unable, with the powerful aid of steam and everything else she could bring into service, to pass over; she was obliged to give her freight and passengers to a smaller boat, abandon the trip, and return to Buffalo. Other vessels have been compelled not only to take out all their cargoes, but even their chains and anchors have been stripped from them, before they could get over. To meet this difficulty as far as possible, the commercial men around these lakes have imposed a tax upon their shipping, to dredge out and deepen the channel through these flats."
Col. Graham, in one of his Reports to the Department, writes as follows upon the importance of this improvement in a military point of view:—
"Since the opening of the Sault Ste. Marie Canal, the only obstacle to the co-operation of armed fleets, which in time of war would be placed upon Lakes Superior, Michigan, and Huron, with that which would be on Lake Erie, is at St. Clair flats. That obstacle removed, and a depth of channel of twelve feet obtained there, which might be increased to sixteen or eighteen feet by dredging, war-steamers of the largest class which would probably be placed on these lakes would have a free navigation from Buffalo at the foot of Lake Erie to Fond du Lac of Lake Superior.
"It would be very important that these fleets should have the power of concentration, either wholly or in part, at certain important points now rendered impracticable by these intervening flats. It would no doubt often be important as a measure of naval tactics alone. It would as often, again, be equally necessary in coöperating with our land-forces. It might even become necessary to depend on the navy to transport our land-forces rapidly from one point to another on different sides of the flats.
"When a work like this subserves the double purpose of military defence in times of war, and of promoting the interests of commerce between several of the States of the Union in time of peace, it would seem to have an increased claim to the attention of the General Government. If any work of improvement can be considered national in its character, the improvement of St. Clair flats, in the manner proposed, may, it is submitted, justly claim to be placed in that category."
The plan proposed by the United States Engineers for this improvement is to construct two parallel piers of about four thousand feet long, as a permanent protection to the channel-way, and to dredge out a channel between these piers, six hundred feet wide and twelve feet deep. The cost of this work is estimated at about $533,000. This may seem a large sum of money; but when it is considered that the value of the commerce which passed over these flats in the year 1855 was ascertained by Col. Graham to be over two hundred and fifty millions of dollars, or considerably more than the whole exports of the Southern States for the year 1860, more than a million of dollars per day during the period of navigation, and that the increased charge on freights by reason of this obstruction is more than two millions of dollars per annum, which of course has to be paid by the producer, the investment of one quarter of that annual charge in a work which would do away with the tax might seem to be a measure of economy.
To show the importance of these lake-harbors, and the vast amount of commerce which depends upon them, and which has grown up within the last twenty years, we will give an extract from another of Col. Graham's very interesting Reports, upon the Chicago harbor.
"The present vast extent and rapidly increasing growth of the commerce of Chicago render it a matter of absolute necessity, in which not only Illinois, but also a number of her neighboring States are deeply interested, that her harbor should be kept in the best and most secure state of improvement, so as always to afford, during the season of navigation, a safe and easy entrance and departure for vessels drawing at least twelve feet water.