The four permanent gauges on the Osage and the one on the Gasconade River, referred to in last years' report, have been continued. See report of Assistant Engineer A. H. Blaisdell, Appendix B.

Assistant Engineer Seddon, in addition to the routine duties of his office, has made special studies upon data collected in regard to the emptying and filling of locks, upon the probable effects of the proposed dam at Lock No. 1, Osage River, on the flood flow of that stream, and upon the recent floods of the Mississippi River and its tributaries. (See Appendix L.)

As a matter of useful information relating to the navigation of the Missouri River, a list of the steamboat wrecks which have occurred on the river from the beginning of steamboat navigation down has been prepared. The information so collected embraces the name and description of boat, trade engaged in, date, locality and cause of wreck, with additional data in many cases. An analysis of these data, showing the principal causes of steamboat disasters, is given in the special report of Captain Chittenden, Appendix D. See also list of bridges, Appendix E.

CONSTRUCTION.

OMAHA, NEBR., AND COUNCIL BLUFFS, IOWA.

This work was under the charge of the secretary of the Commission, with Assistant Engineer Samuel H. Yonge in immediate control.

The present project, approved by the Chief of Engineers August 10, 1896, provides for the completion of the longitudinal training dike and the system of cross dikes designed to restore the shore line at the deep bend about a mile above the Interstate Bridge, and also to make the necessary repairs to the existing works in that vicinity. The project was in reality only a completion of that of 1895.

The plant for the prosecution of the work was mostly taken from that previously used on the Osage division of the first reach. It was towed to the locality of the work, and reached there on the 20th of September. Work was immediately begun and was carried on continuously until December 19, when the plant had all been secured on the bank, and the force of employees furloughed or discharged.

Operations were resumed immediately upon the breaking up of the ice in the spring, the launching of the plant having been completed on the 3d of April. Operations were concluded May 10 by the completion of the project, and the plant was sent to Nebraska City, Nebr., for work at that point.

The work at Omaha and Council Bluffs under the last project was conducted under considerable difficulty, particularly that done during the spring high water, but it was nevertheless completed very nearly on time and within the limit of the allotment provided for it.

For the details of the work see the report of Mr. S. H. Yonge, United States division engineer, Appendix F.

NEBRASKA CITY.

This work was under the charge of the secretary of the Commission until May 31, and since that time under the charge of the president of the Commission. Mr. Samuel H. Yonge, United States assistant engineer, has been in local charge.

The last work executed by the Commission in this vicinity was the revetment of 5,750 linear feet of bank of Nebraska City Island, completed in 1890.

In the fall of 1896, the head of this revetment commenced to undermine, and a caving pocket formed in the bank just above, due to changes in the channel, through a reef extending a long distance up the river. In May, 1896, about 400 linear feet of the revetment had been washed out, and the pocket having enlarged to about 900 feet in width, the safety of the remainder of the revetment was imperiled. It was proposed to check the enlargement of the pocket by constructing three short dikes across it.

Piles and other material, based on soundings taken in March, 1897, had been procured, but when the plant was ready at the site to begin work on May 11, it was found that the depth of water in the pocket had been much increased by scour and that most of the piles were too short.

It was not practicable to procure longer piling before the expected June rise, which would further injure the old work unless protection works were at once put in; the project was slightly changed by substi tuting two 3-row dikes for the proposed three 2-row ones, and the adding of a short 2-row structure in the eddy a short distance below.

The requirements for long piling were partly overcome by procuring cottonwood piles in the near vicinity, and by splicing the shorter pine piles already on hand.

Dikes Nos. 1 and 2 are 131 and 130 feet long respectively and were built at an average cost of $1,755 each.

The short dike below cost about $264. Work was commenced on May 19 and was completed on June 21, several suspensions of work being necessary on account of high water.

In bracing the dikes, besides the usual direct top braces and wales, diagonal cable stays and direct ground braces were used, the latter detail being used for the first time.

A full explanation of the method of bracing and the means employed is given in the report of Mr. Samuel H. Yonge, assistant engineer, Appendix G.

The changeable channels through the reef, before referred to, also produced a caving of the banks in the Nebraska City side of the river, which, if allowed to continue, would endanger the safety of the city water works and other municipal interests.

An examination, disclosing the fact that bed rock existed too near the surface to build protecting works of piles, it was decided to riprap the bank with stone at three places or sections of 50 linear feet each where apparently it was most needed.

This work at the end of the fiscal year is about one-third completed.

SYSTEMATIC IMPROVEMENT OF FIRST REACH.

This work has been under the charge of the president of the Commission. Mr. S. Waters Fox, United States division engineer, was in local charge of the Gasconade Division during the entire year, and of the Osage division after September 6, when he relieved Mr. S. H. Yonge, division engineer.

The river and harbor appropriation act of September 19, 1890, directed that with certain specified exceptions the appropriation therein made for the Missouri River below Sioux City, Iowa, should be expended in systematic improvement of the river from its mouth up, in reaches to be designated by the Commission. In accordance with these provisions, the above portion of the river was, for purposes of systematic improvement, divided into six reaches, the first of which extends from its ENG 97-241

mouth to the mouth of the Osage River, a distance of 141 miles. The improvement of the first reach was begun in the summer of 1891, near the head of the reach, and has since been continued under the subsequent appropriation acts. To obtain a proper heading for the work it was found necessary to go about 14 miles above the mouth of the Osage, to the head of Murrays Bend, from which point the work thus far doné extends about 45 miles downstream, or to the mouth of the Gasconade River. For convenience of administration, these 45 miles have been divided into the Osage division and the Gasconade division. The Osage division extends from the head of Murrays Bend to Isbell Station; the Gasconade division from the latter point to the mouth of the Gasconade River.

The Commission's annual reports for 1895 and 1896 contain a general description of the works, whether then finished or proposed, for the improvement of the river within the above 45 miles.

OSAGE DIVISION.

The work of the year has been done under an allotment of $164,000 from the appropriation of June 3, 1896, for continuing the systematic improvement of the first reach, and in accordance with project approved by the Chief of Engineers August 26, 1896.

Junction of Osage and Missouri rivers.-The project for bringing the Osage into the Missouri above Dodds Island and closing the chute south of the island was adopted in accordance with a resolution of the Missouri River Commission of July 17, 1896. This work necessitated a cut for a new channel for the Osage River through Osage Point; the degrading of Dikes 25 and 26; the closing of the breach on Dike 19 B; the construction of Dike 19 A; the removal of a portion of Dike 19 B; the degrading of the inshore portion of Dike 19 B, the Osage Dam, and the Osage Point revetment, and other minor works, the nature of which would be dependent upon these above described.

Cut through Osage Point.-The only work done on this part of the project was the acquisition of the right of way, and the quarrying of about 11,093 cubic yards of rock for revetment of the left bank of the new channel.

Degrading Dike 25.-Between the 3d and 6th of December the outer 42 feet of dike and 50 feet of its trail were cut down to an elevation of 2.2 feet above standard low water.

Degrading Dike 26.-This work was accomplished between the 4th and 8th of December.

Dike 19 B.-The closing of gap at shore end was commenced October 13 and completed October 23. The removal of that portion which lay within proposed Osage Channel was begun December 3 and continued throughout the winter as weather and stage of river would permit. The degrading of that portion of the dike beyond the limits of low water was begun at the same time.

Dike 19 A.-This structure is intended to constitute (with an earthen embankment) the left bank of the Osage River from Osage Point to its junction with the Missouri. It was begun on October 16 and completed November 28. The winter floods did it considerable damage, that of January injuring 310 feet of curtain, and the April rise developing a breach in the dike, and scouring a waterway around the west end of the structure. These damages were repaired and the dike extended to 19 A by June 25 of the present year.

OTHER DIKE WORK.

Sheer Dike 29A.-The purpose of this dike is to ward off drift from Dike 29A. The structure, which consists of clusters of three piles each, spaced 25 feet apart, and located at an angle of 60 degrees with the dike, was constructed between October 23 and October 30. This dike served its purpose perfectly, and, although it suffered some injury from drift, it protected entirely the main dike.

Degrading Dike 29A.-Three hundred feet of this dike was lowered to 2.6 feet above standard low water at outer end, 5.4 feet above at inner end. This work was done between November 25 and December 3.

Dike 34.-Extended 191 feet between October 31 and November 24. Dike 35.-Extended 247 feet between November 2 and November 25. Dike 36.-A breach 109 feet long was repaired.

Dike 29 B.-A small breach in this dike was closed between April 17 and April 20.

REVETMENT REPAIRS.

Murrays Bend.-Various small breaches in this revetment, which occurred at different times during the year, were repaired.

DAMAGE TO WORKS.

Damages of a more or less serious nature were caused by the floods to Dikes P, 19A, 191A, 19B, 30, 32, 29A, 29B, and I.

PLANT.

The plant underwent no extensive repairs during the year, but a considerable amount of small repairing was done. In accordance with instructions from the Secretary of War, dated April 20, the steamers Golden Gate and Alert were sent to the Lower Mississippi on flood-relief duty. They left the boat yards April 23, and returned, the Alert May 19 and the Golden Gate May 23.

SURVEYS.

Various special observations and surveys were made during the year, the principal being a survey of the locality at the mouth of the Osage River, the low-water survey of the Osage division, and numerous observations upon scouring effect of the current around the ends of the dikes. For details of the work see the report of Assistant Engineers S. Waters Fox and Samuel H. Yonge, Appendices I and H.

GASCONADE DIVISION.

The operations of the year comprised revetment and dike construction, as well as the repairing of both kinds of work, the construction of an experimental bank-head designed as a substitute for revetment, the care and repair of plant, surveying, the preparation of projects and maps with estimates of cost, examinations and special reports on conditions at several points outside of first reach, and miscellaneous incidental work.

The work was done under an allotment of $164,000 for continuing the systematic improvement in first reach, and in accordance with the project approved by the Chief of Engineers August 26, 1896.

REVETMENT.

Heckmann Island No. 3.-The project for improvement of Straubs Bend contemplated the protection of the south bank of the island by a revetment extending from the head of the island well into Boatwrights Chute. Work began August 12 and was completed September 24.

Repairs.-The aggregate length of revetment on the Gasconade division is now 8.9 miles, and all in excellent condition. Only a very small amount of repair work has been necessary.

DIKE WORK.

Two entirely new dikes were built in this division, viz, XI A and XI B, their purpose being to fair up the middle section of Chamois Bend. Dike XI A. Work on this dike was begun June 14 and completed June 27. The structure is 240 feet long. The first four bents are 2-row and the others 3-row work.

Dike XI B.-Work began June 11, and was nearly completed when, on the night of June 24, a severe storm partially destroyed the dike. This was followed by a sudden rise of the river, which suspended operations on June 28.

Dike XXXII.-Work had been commenced on this dike early in the spring, but had been suspended on account of high water. It was resumed on the 10th of August and completed on the 26th of the same month.

Dike XXXIV.-Work on this dike had also been commenced in the spring, but was suspended on account of high water. It was resumed October 5 and completed October 31.

Dike XXIII-Work was begun on this dike on October 5 and completed October 31.

Dike XV.-The extension of this dike to the project line was commenced November 2 and completed December 6.

DIKE REPAIR AND ALTERATION.

Repair work was confined to three dikes, I B, I A, and XX A, which had received injuries from the floods of May, 1896. The new work on the last-mentioned dike was altered from the original plan of 4-row work into 2-row in the outer breach and to 3-row work inshore; that on dikes I B and I A to 2-row from 3-row, as originally planned.

BANK-HEAD.

An experimental device called a bank-head was built at the foot of Chamois Bend, about 3,850 feet below the lower end of the revetment. It is intended, by means of the bank-head, to firmly hold the bank at that point, and it is expected that the stretch of bank between it and the revetment will become stable after a certain amount of recession, and that, these conditions having obtained, there will be no necessity for revetting this stretch of bank, as originally proposed.

The structure was practically completed by March 26. Although it was subjected to a very severe test by a change in the line of approaching flow, due to other influences some 2 miles up river, the structure stood well. Its influence on the conditions of flow was in close accord with expectations. It has so far accomplished the object for which it was built, in that the 3,850 feet of bank above has not receded from erosion beyond a certain line, and the original bank below for a distance