Estimate of cost of combined navigation-power development, international rapids section, St. Lawrence River (December 1950 cost levels)

Breakdown estimate of cost of deepening the upper Great Lakes connecting chann els in connection with the proposed St. Lawrence seaway project (Dec. 1950 cost levels)

1 Based upon available hydrographic data and office studies. No soundings or borings taken. No detailed studies made regarding St. Clair River compensating works, or the Detroit River lock planned for the projects of 30 and 35 feet depth. These estimates are therefore of a preliminary nature.

Estimated cost to provide entrance channels and turning basins to outer docks at typical United States harbors on the Great Lakes in connection with the proposed St. Lawrence seaway project (Dec. 1950 cost levels)

On March 19, 1941, the Governments of the United States and Canada negotiated an agreement, printed as House Document No. 153, Seventy-seventh Congress, first session, providing for the construction of dams and power works in the International Rapids Section of the St. Lawrence River and for completion of the Great Lakes-St. Lawrence deep waterway. Initiation of construction is dependent upon approval of the agreement by the Congress of the United States and the Parliament of Canada, together with the appropriation of necessary funds.

Briefly, the agreement proposes that both countries execute certain works to provide a deep waterway with a controlling channel depth of 27 feet and 30 feet over lock sills from the head of the Great Lakes to Montreal, and to develop a large block of hydroelectric power in the International Rapids Section, St. Lawrence River, near Massena, N. Y., to be evenly divided by the two countries. A general map showing the project's high lights is attached.

EXISTING CONDITION OF WATERWAY

The Gulf of St. Lawrence, the St. Lawrence River, and the Great Lakes provide a continuous waterway extending from the Atlantic Ocean into the heart of the continent. From the strait of Belle Isle, at the mouth of the Gulf of St. Lawrence, the sailing distance to Duluth at the head of Lake Superior is about 2,340 miles and to Chicago at the head of Lake Michigan it is about 2,250 miles. From Montreal, which is at the head of deep-draft ocean shipping on the St. Lawrence River, the sailing distance to Duluth is 1,330 miles and that to Chicago is 1,240 miles; about 975 miles of the distance to Duluth and 950 miles of the distance to Chicago are in the open Great Lakes.

From the ocean to Quebec, the head of tidal flow, a 35-foot channel exists. From Quebec to Montreal, which is 1,000 miles from the sea, there is a 35-foot project channel depth which has been completed to a 32.5-foot depth. The bottleneck to navigation between ocean and lake ports is now a depth of 14 feet in the six canals around the rapids of the St. Lawrence River in the 114 miles between Montreal and Ogdensburg, N. Y. On the St. Lawrence between Ogdensburg and Lake Ontario there is now a channel generally 27 feet deep. The Welland Ship Canal, connecting Lakes Ontario and Erie, has a channel depth of 25 feet. In the connecting rivers and ship channels which govern navigation between Lakes Erie, Huron, Michigan, and Superior the available depth is at least 21 feet for up-bound traffic and at least 25 feet for down-bound traffic. For through navigation the present controlling headroom under bridges is as follows: 135 feet on the St. Lawrence above Montreal except for 94 feet at a railway lift bridge across the Lachine Canal near Montreal; 120 feet on the Welland Canal; and 133 feet between Lake Erie and Lake Huron. Improvements under the seaway plan will provide a controlling channel depth of at least 27 feet from the head of the Great Lakes to Montreal, with locks having a depth of at least 30 feet over the sills, and with bridges affording a headroom of at least 120 feet.

GREAT LAKES CONNECTING CHANNELS

Commencing at the head of the Great Lakes the first major item in the seaway plan is a new deep-draft lock in the group connecting Lakes Superior and Huron at Sault Ste. Marie, Mich. That lock, known as the MacArthur lock, has been provided by the United States under the authorized Federal project for St. Marys Falls Canal. It is 800 feet long, 80 feet wide, and 31 feet deep with immediate approach channels 27 feet deep. Normal lift is 21.7 feet. Construction of that lock was rapidly prosecuted as an emergency measure and was opened to traffic in July 1943. Additional dredging

to provide a channel depth of 27 feet between Lakes Superior, Michigan, and Huron would be required and under the agreement it would be accomplished by the United States.

The next item, proceeding downstream, is the deepening of the connecting channels between Lakes Huron and Erie to 27 feet which would be undertaken by the United States, together with providing such compensating works as necessary in the St. Clair River. Present project depths are generally 25 feet in the down-bound channels and 21 feet in the up-bound channels.

WELLAND CANAL

The present Welland Ship Canal, connecting Lakes Erie and Ontario, was officially opened in 1932. It was constructed by the Canadian Government and replaces the former canal, which was the Third Welland Canal. The present canal is 27.6 miles long, 200 feet wide at the bottom, 310 feet at the water surface, and 25 feet deep. The eight locks have a length of at least 800 feet, width of 80 feet, and depth over sills of 30 feet. There are seven lift locks varying from 43.7 to 47.9 feet head, together with one guard lock, aggregating 327 feet total lift. Under the agreement the Canadian Government would increase the channel depth to 27 feet.

THOUSAND ISLANDS SECTION

Leaving Lake Ontario the first 68 miles of the St. Lawrence River comprise what is known as the Thousand Islands section, extending from Tibbetts Point, N. Y., to Chimney Point (Ogdensburg), N. Y. Channel improvements in this section were accomplished by the . United States and Canada between 1929 and 1933, consisting of the removal to a depth of 27 feet of scattered shoals to afford a straightened and widened channel generally in excess of 450 feet. Under the seaway plan additional rock shoals would be lowered to provide a channel having a minimum width of 450 feet throughout and a depth of 27 feet based upon a new datum plane which is one-half foot lower at Lake Ontario than the former datum plane. This work, located in American waters, would be done by the United States.

INTERNATIONAL RAPIDS SECTION

The next 46 miles of the St. Lawrence River, extending from Chimney Point to St. Regis, N. Y., is known as the International Rapids section. It is in this section that major navigation and hydroelectric-power developments are proposed jointly by the two Governments. Navigation in this reach is presently governed by lateral canals along the Canadian side of the river, with locks 252 feet long, 44 feet wide, and 14 feet deep over the sills. Those facilities were provided by Canada generally before the turn of the century. A brief description of the principal works proposed in the international section under the seaway and power project follows:

(a) A channel through the International Rapids section at least 27 feet deep with alinement, widths and current velocities deemed satisfactory for the anticipated traffic: The channel would be located partially in the open sections of the river and partially in land cuts, with a bottom width varying from 440 feet in the land cuts to 600 feet or

more in the river. Three locks are proposed, each 800 feet long, 80 feet wide, and 30 feet deep over the sills. The Point Rockway lock would be located in the Point Rockway Canal just downstream from the Iroquois control dam, described below, and would have a normal lift of from 1 to 5 feet. The Robinson Bay and Grass River locks would be located in the 8-mile Long Sault Canal skirting the American shore in the vicinity of the power development, described below, and they would have normal initial lifts of 38 and 43 feet, respectively.

(b) A control dam at Iroquois Point near the upper end of the International Rapids section: The spillway, 2,390 feet long, would be a concrete gravity structure having a maximum height above foundation of 118 feet to the deck. There would be 40 gate openings each 50 feet wide extending down to a continuous concrete sill at the mean elevation of the river bed. Operation of the vertical lift gates would be by means of two traveling gantry cranes. The 1941 agreement contemplates that the powerhouse shall be operated initially with a maximum pool elevation of 238 feet. With such operation the control dam becomes necessary to maintain natural Lake Ontario levels. The dam would also serve generally as a flow regulator and would aid in the formation of a solid ice sheet from the control dam upstream to the Galop Rapids, thus reducing the amount of frazil that would otherwise form with adverse effect upon efficient powerhouse operation during the winter season.

(c) The Long Sault (main) Dam near Massena to connect the American mainland with the head of Barnhart Island and the powerhouse, from the foot of Barnhart Island to the Canadian shore, as an extension of the main dam: Normal initial head would be 81 feet. Long Sault Dam would be a concrete gravity structure having a maximum height of 145 feet above foundation. It would have an overflow spillway flanked by concrete gravity bulkhead sections and earth dikes. The 40 spillway openings each 50 feet wide would be controlled by vertical lift gates. Twenty-two of these gates would be operated by two traveling gantry cranes, and the remaining gates by individual motors. Spillway crest length would be 2,390 feet, of which 2,000 feet would be clear opening. Spillway crest elevation would be 221, or 21 feet below ultimate normal pool level of 242. The Barnhart Island powerhouse would comprise a structure about 3,600 feet long and 180 feet wide. Thirty-six units having a combined turbine capacity of 2,200,000 horsepower at 81-foot head, and a combined installed generator capacity of 1,881,000 kilowatts, would be constructed, one-half of which would be on the American side of the international boundary.

Thus the amount of power to be developed would be divided equally between the two countries. Average annual power generation is estimated at 12.6 billion kilowatt-hours. That block of power is the largest remaining for development at any one point on the North American Continent. The St. Lawrence River is unique among the rivers of the world in that the tremendous storage capacity of the Great Lakes regulates its discharge to produce a relatively constant flow. The ratio of the maximum to minimum flow is only 2.2, as compared to a ratio of about 45 for most rivers of comparable size. Observed mean monthly flow for an 80-year period is 237,000 cubic feet a second, varying from a maximum of 314,000 to a minimum of 144,000. Total drainage area above the foot of the International

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