TOPOGRAPHICAL CHART OF SITE OF MISSISSIPPI RIVER POWER Co.'s PLANT. (LOCATION OF DAM INDICATED ON GOVERNMENT CHART.)

bers. After public hearings and an investigation, the commission reported favorably on the project.

AUTHORIZATION.

In view of this favorable attitude and report, on April 21, 1904, a bill was introduced in Congress to secure the right to build a dam completely across the Mississippi at the foot of the Des Moines Rapids. This bill was favored by the legislature of the State of Illinois, which, on January 17, 1905, by joint resolution, memorialized Congress, urging its passage. The State Legislature of Iowa also indorsed the enterprise. On January 27, 1905, the bill passed the Lower House; on February 2, 1905, it passed the Senate; on February 9, 1905, it received the approval of President Roosevelt and became a law.

This law was public act No. 65, entitled "An act granting to the Keokuk and Hamilton Water Power Co. rights to construct and maintain for the improvement of navigation and development of water power a dam across the Mississippi River." It provides:

That the assent of Congress is hereby given to the Keokuk and Hamilton Water Power Company, a corporation created and organized under the laws of the State of Illinois, its successors, and assigns, to erect, construct, operate, and maintain a dam, with its crest at an elevation of from thirty to thirty-five feet above standard low water, across the Mississippi River at or near the foot of the Des Moines Rapids, from Keokuk, Iowa, to Hamilton, Illinois, and to construct, operate, and maintain power stations on or in connection with said dam, with suitable accessories for the development of water power, and the generation, use, and transmission therefrom of electric energy and power to be derived from the Des Moines Rapids on the Mississippi River.

The United States Government had constructed in 1877, and was maintaining along the Iowa shore as an aid to navigation a dry dock, canal, and a series of three locks, the structure extending in all 11 miles from Keokuk to a point below Fort Madison, but above the swiftest part of the rapids. The dock, canal, and locks had for years made feasible the only practicable river intercourse between points above and below the barrier.

In order to continue this means of communication, and in order that the Government might receive a return for the perpetual franchise granted the company, there follows in the bill this proviso:

That in lieu of the three locks and the dry dock, with their appurtenances, now owned and operated by the United States, at the Des Moines Rapids Canal, the said Keokuk and Hamilton Water Power Company shall build, coincidentally with the construction of the said dam and appurtenances, at locations approved by the Secretary of War, a lock and dry dock with their appurtenances; the said lock shall be of such a kind and size, and shall have such appurtenances and equipment as shall conveniently and safely accommodate the

present and prospective commerce of the Mississippi River; the said dry dock and its appurtenances shall be such as to give space, facilities, and conveniences for the repair of vessels at least equal to those afforded by the existing Government dry dock and shops at the Des Moines Rapids Canal.

Other conditions provide for further approval by the Secretary of War and upon completion place in the United States the ownership and control of the lock, dry dock, and their appurtenances, and the operation and maintenance thereof.

As still further protection to navigation, and in the interest of fisheries, section 2 of the act requires:

That the withdrawal of water from the Mississippi River and the discharge of water into the said river, for the purpose of operating the said power stations and appurtenant works, shall be under the direction and control of the Secretary of War, and shall at no time be such as to impede or interfere with the safe and convenient navigation of the said river by means of steamboats or other vessels, or by rafts or barges: Provided, That the said company shall . construct such suitable fishways as may be required from time to time by the Secretary of Commerce and Labor.

Under authority of this act, after the delay of preparing to finance the construction, in 1909 work was actually begun to continue until completion, it is estimated, some time before July 1, 1913.

In direct charge of the hydraulic construction is Mr. Hugh L. Cooper, of New York. The Stone & Webster Engineering Corporation, of Boston, has direct charge of the electrical installation, including the transmission and distributing lines.

CHARACTER OF RIVER BED.

The site of this dam and hydro-electric plant, as a glance at the map will show, is above the junctions with the Mississippi, of the Ohio, Missouri, and Illinois Rivers. It is at a point where the three States of Iowa, Missouri, and Illinois touch, 140 miles from Des Moines, 140 miles from St. Louis, and 220 miles from Chicago.

The dam itself is being built upon a river bed of blue limestone in a region stable from a geological point of view. The surface of the river bed at this point is naturally clean and free from the cracks and fissures of rock of igneous origin. The average depth of the river at this point is from 5 to 6 feet and the variation is slight.

Under an act of Congress July 25, 1866, a bridge joining Keokuk and Hamilton was built. This bridge crosses the river at a point 1,066 yards below the location of the Keokuk Dam. The following description of the river bed in the vicinity of this bridge is taken from page 1006 of the Report of the Chief of Engineers, United States Army, for the year 1878, Part 2:

The river in its natural condition at this place is about 2,600 feet in width at ordinary low water and about 5,500 feet in width at flood stages. The bed of the river is limestone, of the same character as that of the whole Des Moines Rapids, which extend from this place to Montrose, about 11 miles.

On page 313 of Report of the Chief of Engineers, United States Army, for the year 1867, is found a description of the Des Moines Rapids, in which the following extract appears:

This erosive action, though productive of such remarkable results, has not been carried sufficiently far to render the river through this part of its bed, available at all times for the purposes of navigation. From Fort Madison to Montrose, the river is about 2,500 feet wide, and sufficiently deep; but in the rapids its bed of limestone rock, which by some unknown cause seems to have been hardened to a greater degree than the corresponding stratum above and below the rapids, has resisted the action of the water, while its sides have given way. The result is that this mass of rock remains there, acting exactly as an artificial dam whose upper surface slopes about 22 feet in 11 miles, and conforms very nearly to the plane of stratification of the rock through which the channel is cut. The bluffs extend along the banks of the river throughout the length of the rapids, presenting a rock escarpment at the present high watermark with a sloping gravel beach to low water, and also another escarpment of rock at 105 feet above the present water level, having, likewise, a sloping beach at its foot.

FLOW OF RIVER.

Readings of the stage of the Mississippi River at various points have been made by the United States Government since 1868. These readings have been published as part of the records of the Mississippi River Commission and of the United States Weather Bureau. Besides reading the stage of the river the Government has, through the United States Army and the Mississippi River Commission, observed at various times and at various points the discharge of the water. The results of these discharge measurements also form part of the records of the Mississippi River Commission as well as of the United States Engineers. In addition to these, various observations have been taken under the direction of Mr. Cooper. For the purpose of determining the amount of power available all of the above observations, and particularly those establishing a minimum flow, have been valuable. So far as is known to the engineers of the development, the lowest measured discharge was recorded by Montgomery Meigs, United States Civil Engineer, in September, 1891, when at a time that the commonly accepted low-water marks on Mechanics' Rock, just above Keokuk, showed water lower than the record of 1864, there was observed a discharge of 21,389 cubic feet per second. second. Other observations of minimum discharge are shown in the tables which follow, being the lowest records of which the engineers of the development have authentic knowledge.