APPENDIX 7.

REPORT OF LIEUTENANT JOHN MILLIS, CORPS OF ENGINEERS, ON OPERATIONS IN FOURTH DISTRICT.

UNITED STATES ENGINEER OFFICE,

New Orleans, La., June 2, 1892.

SIR: I have the honor to submit the following report upon the works in charge of this office under the Mississippi River Commission for the period from July 1, 1891, up to May 31, 1892, in accordance with recent instructions from the Commission: The office has charge under the Commission of the Fourth district, which extends from Warrenton, Miss., 7.4 miles below Vicksburg, to the Head of the Passes. The district comprises 484 miles of the river and includes the works of improvement at Natchez, Miss., and Vidalia, La., at the junction of the Mississippi, Red, and Atchafalaya rivers, near Turnbull Island, Louisiana, and at New Orleans Harbor. It also comprises the work of construction, repair, and maintenance of a portion of the levee system of the district; the maintenance of certain gauges, and certain surveys, observations, and other special work.

IMPROVEMENT OF THE MISSISSIPPI RIVER AT NATCHEZ, MISSISSIPPI, AND VIDALIA, LOUISIANA.

At its meeting of November 26, 1890, the Commission directed that a resurvey of those portions of the river which included the proposed works of improvement be made, and the sum of $1,500, was allotted for the purpose.

This survey was made as directed, and the report and map submitted with the last annual report from this office.

There have been no additional funds allotted and no further work was done during the past year.

The detrimental action of the river which the proposed works are intended to arrest still continues and probably at an increasing rate.

Amount that can be profitably expended during fiscal year ending June 30, 1894...

$250,000

WORKS OF IMPROVEMENT AT THE JUNCTION OF THE MISSISSIPPI, RED, AND ATCHAFALAYA RIVERS, AT TURNBULL ISLAND, LOUISIANA.

The condition of the river channels in this vicinity is somewhat peculiar and confusing. Turnbull Island is approximately rectangular in shape and is about 6 miles long east and west, with an average breadth north and south of 2 miles. It is situated on the west side of the Mississippi River, about 200 miles above New Orleans, and its eastern extremity is now about a mile from the west bank of the river.

The island was formerly a peninsula connected by a narrow neck to what is now the east bank, and the main river passed around its western end. The Red River then emptied into the Mississippi opposite the northwest point of the peninsula, and the Atchafalaya was an outlet bayou or diffluent whose head was opposite the southwest point of the peninsula, about 2 miles below the mouth of the Red. Such was the condition of affairs at least as far back as 1578, the date of the earliest recorded observation by civilized man, and no material change took place until 1831, when the main river cut through the narrow neck, forming what is now called Turnbull Island.

The cut off is said to have been made or assisted by a Captain Shreve, and in some reports on this subject mention is made of difficulties of navigation which had previously been experienced owing to the shoal water found at the mouth of Red River during the low-water season, which the cut-off was designed to remedy.

It would seem entirely probable that prior to the cut-off a bar might have been

formed at the mouth of Red River, which at low water would have impeded navigation, the same as now occurs at the mouth of the White, Arkansas, Yazoo, and other tributaries, and it is a matter of record that even since the cut-off and until a comparatively recent date the head of the Atchafalaya went nearly dry at low water, as does the outlet Bayou Lafourche at the present time.

Since the requirements of navigation prior to 1831 were quite different from those that exist at this date, comparisons of low-water difficulties, in the absence of accurate and reliable surveys, as they existed before and after the cut-off, are not very reliable.

A greater portion of the old river bed which was abandoned by the main river when the cut-off was made has become filled up with sediment, which has formed extensive bars that are dry except at high water and are thickly grown up with young trees. There is, however, a continuous channel around the island, much narrower than the original river, which still remains clear and navigable at high water, though the bottom of the portion north of the island is dry at low water and navigation through that portion south of the island is maintained during extreme low stages with difficulty. There are, besides these channels, various sloughs, lakes, and ponds in the old river bed that retain more or less water throughout the low-water

season.

Another important change that has taken place since the cut-off is the general enlargement of the Atchafalaya in depth and width and its tendency to receive at certain stages the entire discharge of the Red River as well as a portion of that of the Mississippi. In fact the Red and Atchafalaya, with that portion of the old Mississippi River at the western end of the island between what was formerly the mouth of the Red and the head of the Atchafalaya as a connecting link, may now be regarded as forming really one river, which has a general direction parallel to that of the Mississippi, and which approaches the latter at Turnbull Island to within a distance of about 6 miles.

It must be noted, however, in considering the Red and Atchafalaya as one river, that a marked change in the characteristics of this river takes place at Turnbull Island. For a long distance above this point the slope is very gentle and the current sluggish and at certain periods nearly slackwater, or even a temporary reversed current may exist. The banks are low, heavily wooded, unleveed, always overflowed in high water, and are uninhabited.

Below Turnbull Island the section of the river, though constantly enlarging, is still much smaller than that immediately above, and the banks are high and cultivated. The west bank is leveed down to West Melville, 30 miles below Turnbull Island, while on the opposite bank the levee system now extends down about 17 miles below the island. The slope is much greater than that above, the current is swift, and the presence of numerous rafts or jams of trees and logs produces eddies and boils which render navigation unsafe without an experienced pilot. The banks are caving rapidly in many places.

About 40 miles below Turnbull Island the Atchafalaya begins to spread out into an intricate network of interconnecting bayous and lakes, mostly shoal, which finally reunite in the vicinity of Morgan City. The Bayon Teche, which is the principal distinct bayou to the westward of the Atchafalaya system, also comes in near Morgan City, forming a broad, deep bayou. This bayou continues, under the name Atchafalaya River, and after a course of about 35 miles, mainly through low sea marsh, it finally expands into Atchafalaya Bay, a shallow arm of the Gulf of Mexico. The entire Red and Atchafalaya rivers system comprises in high water a total length of about 4,300 miles of navigable river, and in low water about 345 miles for a 3-foot draft and 132 miles for a 5-foot draft.

There is no available deep-water port on the Lower Atchafalaya, and the outlet for this entire system is now through the old Mississippi River channel south of Turnbull Island, which here forms a connecting link with the Mississippi, and thence by the Mississippi to the seaport of New Orleans. At high and medium stages of the river the channel north of Turnbull Island is also available, but it is less direct than the lower channel and is now seldom used.

The difficulties now experienced result from a tendency of the Old River to become filled up, owing partly to the absence of a definite current of sufficient strength to prevent the deposit of sediment and partly to the sliding down of the soft and recently formed banks. At low water the navigable connection between the Red and Atchafalaya system and the Mississippi is almost invariably seriously impaired and has been entirely interrupted in several instances.

Regarding the Red and Atchafalaya as one river, the direction and force of the current in the branches of Old River will evidently depend upon the relative height of the water in the Red and Atchafalaya system and in the Mississippi, and according as the one or the other of these two rivers happens to be the higher, or as they are both at the same level, the current through Old River is toward the east, toward the west, or is nil. In the first case there is a greater or less discharge from the Red and

Atchafalaya system into the Mississippi; or, otherwise stated, Red River proper has then two outlets or branches, one through the Atchafalaya and one into the Mississippi, while the discharge of the Mississippi is confined entirely to its own channel. In the second case the discharge of the Red and Atchafalaya is confined to its own channel, while a portion of the water of the Mississippi is diverted from that river and passes down the Atchafalaya.

In the third case the two river systems are independent so far as their discharge is concerned, which is then practically the same as would be the case if no connection existed.

During the flood period other influences have a material effect. The levee system on the west bank of the Mississippi is only completed down to Bougere, about 26 miles above Turnbull Island, and breaks in the levees above sometimes occur. The water from the Mississippi that escapes through breaks or crevasses above and that flowing over the bank between Bougere and Turnbull Island fills up the basin of the Lower Red and tends to maintain an equilibrium in the stage of the water in the two systems at Turnbull Island, and so prevent a current through the Old River. At such times there is a general set southward of the water covering the low swamps between the Lower Red and the Mississippi, forming a cross current which is partly interrupted by the high ground on the northwest portion of Turnbull Island and entirely stopped by the levee along the south bank of Lower Old River. The water from the Mississippi being much more heavily charged with sediment than that from the Red and its tributaries, it seems very probable that under these conditions the rate of filling, particularly in Upper Old River, is materially accelerated.

Since the bottom of Upper Old River has filled up to a level of about 13 feet above the zero of Barbres gauge, all action of a current from one river system to the other below that stage is confined to Lower Old River, and at higher stages the scouring action is no doubt weakened by being divided between two channels instead of being confined to one. The condition of absolutely no current through Lower Old River is comparatively rare, but the two river systems have at times remained at so nearly an equal stage while falling that not sufficient current between the two was formed to move the sediment that had been deposited during high water, and entire closure of the Old River channel during low stages has resulted.

Another serious difficulty has been experienced, due to the caving or sliding down of the soft banks of Lower Old River. The present channel being much narrower than when the main river occupied it, the banks are in many places of very recent formation. When the river falls to a very low stage the water is held in the adjacent ponds and slonghs at a higher level than in the channel, and the underlying strata of the banks are kept saturated. When no longer supported by a high stage of water in the channel, large masses of the soft banks slide down, and their weight causes lumps and ridges of the stiff clay comprising the bottom of the channel to rise up, frequently stopping navigation entirely until these lumps and ridges can be cut out. The general object of the works of improvement now in progress is to rectify the defects above outlined, and the present project proposes to effect this by causing a separation of the Red from the Atchafalaya at Turnbull Island for all stages of these rivers below medium low water, making the Red a proper tributary to the Mississippi when it is at or below this stage, while the Atchafalaya becomes at the same time an outlet or "difilnent" of the Mississippi. The plan also contemplates preventing any further enlargement of the Atchafalaya, and the whole work is designed to have no material effect on the high-water regimen of the various rivers involved, and to produce no greater danger of injury to property from overflow than now exists.

This general project contemplates the following work: A series of low relief dams or sills, not to exceed six in number, to be built in the Atchafalaya proper at intervals of about a quarter of a mile. These dams to be located below the mouth of Bayou Des Glaise, near Simmesport, about 5 miles below Turnbull Island. These dams are designed to prevent further enlargement of the Atchafalaya and to limit its discharge capacity. They are to be built up of successive layers of mattresses made of willow brush and timber, ballasted with stone, and with intervening layers of mixed gravel and clay; the foot mattresses to have a width up and down stream of about 300 feet, and the maximum depth over the crest of the dam to be about 7 feet at extreme low water. The high-water discharge over these dams is intended to be equal to the flood discharge of Red River proper, or about 200,000 cubic feet per second.

A low relief dam is also to be built across the river from the west side of Turnbull Island to the mainland. This dam to be constructed of successive layers of willows and timber mattresses, with stone ballast, and its top and side slopes to be heavily paved with rock. The foot mattress has a maximum width up and down stream of 280 feet. The total length of the dam proper is 935 feet and of the shore-protecting mattresses about 2,039.

This dam is to effect the separation of the Red from the Atchafalaya at all stages of the water below the level of its crest and deflect Red River through Upper Öld

River. To complete the separation of the Red from the Atchafalaya a canal is to be cut from Upper Old River across Carrs Point to the Mississippi, and a dam or obstruction is to be built to close Upper Old River below the canal at some point opposite the eastern end of Turnbull Island.

To secure a navigable channel through Upper Old River it is to be deepened by dredging or otherwise, as may be found most expedient.

During the progress of the above work an attempt is to be made to temporarily maintain navigation through Lower Old River by dredging, washing the bottom with steam tugs, or by other expedients.

Up to the time of the last Annual Report the following work had been accomplished:

Two of the sill dams in the Atchafalaya, Nos. 1 and 3, had been completed.

The sill or foot mattress and shore protection of the Red River Dam were finished. The two lower courses of crib mats were in place and the third course had been constructed and a portion of it sunk in place.

Considerable dredging had been done both in Lower and Upper Old River, though the latter had not proved effective, owing to the nearly fluid state of the material in which the work was done.

The The site of the proposed Carrs Point Canal had been partially cleared of trees, and dredging at the western end in an experimental way had been commenced. telephone line to connect the works with West Melville, the nearest telegraph station, was partially completed and repairs to the barges and other portions of the plant were in progress.

The Commission having directed that the dam be raised temporarily to a height of 5 feet above low water, or the zero of Barbres gauge, in order to assist in increasing the current and consequently the scour in upper Old River during the falling stage of the water, work on the dam was resumed and continued until four courses were in place and a height of about 3 feet above the zero of the gauge obtained. The fourth course was not entirely completed.

The river continued to fall rapidly, finally reaching the unusually low stage of 1 foot below zero on November 17, and it became necessary to suspend work and carry out the instructions of the Commission given in anticipation of a season of extreme low water, and to remove a portion of the dam to permit boats to pass while the low water continued.

A part of the upper course of mats was therefore cut out by means of a dredge, leaving over the dam a clear channel, which for a width of 450 feet has a depth of In making this cut the rock taken out was about 5 feet below the zero of the gauge. distributed over the apron below the dam. Meanwhile dredging was continued in upper Old River, but with no greater success than had attended previous work of the kind in that locality. In lower Old River the usual difficulties were experienced in maintaining the channel during low water, but to a much less degree than ever before at a corresponding stage of the water. Dredging began as soon as the water had fallen sufficiently to permit the dredge to work and was continued until the water became so low that the work had to be suspended.

The Government dredges Menge and Pah Ute and a Hayward bucket dredge, hired for the purpose, were used for this work, and operations were confined to the sand bar at the Mississippi end of Old River, to the "Second Crossing," and to the clay lumps and ridges in the vicinity of Ash Cabin and Dead Tree.

There was also a shoal place near Kellers, in the western portion of the lower Old River, caused by a deposit of sand, and several of the old temporary contracting dikes were repaired and new ones built, with a view to removing the sand by the scour of the increased current produced.

By October 6 the gauge at Barbres had fallen to 2 feet above zero and lower Old River had become impassable for the regular steamboats, though small lightdraft boats continue to go through and transfer freight, between Barbres and Torra's Landing until October 30, when the water had reached two-tenths below zero.

Navigation was suspended entirely from this date until November 27, when both the Red and the Mississippi rose rapidly and navigation was restored.

During the period when navigation was suspended through Old River there were of course difficulties in many other places and through boats could not have safely loaded deeper than 5 feet for any portion of the Red and Atchafalaya system which remained navigable. Even at the extreme lowest stage, 1 foot below zero on Barbres gauge, lower Öld River at no point went entirely dry, as has always been the case heretofore; there being at the shoale st places a depth of not less than 1 foot. During the low water the small snag-boat Florence, which was loaned for the purpose through the courtesy of Capt. J. H. Willard, Corps of Engineers, U. S. A., did excellent work in lower Old River, clearing out snags and logs and the series of piling and old temporary dikes that had previously been constructed in attempts to maintain a low-water channel.

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From soundings taken during the lowest stage it was ascertained that to secure a channel throughout Old River from the Mississippi to the deep water near Barbre Landing, with a depth of 5 feet below zero and a bottom width of 75 feet, would have required the removal of only 75,000 cubic yards and had a dredge capable of working during low water in sand, stiff clay, and soft mud been available, this could easily have been effected, even with a plant of moderate capacity.

It is at least encouraging to note the apparent improvement in the channel of lower Old River. This channel was very much better last fall than it has ever been before at corresponding stages. In only one instance during the period of four years covered by the records of Barbre gauge in this office has the water been lower than it was in 1891. In 1887 the gauge went down to 1.5 feet below zero, and lower Old River went entirely dry. It has frequently been closed completely when the lowest stage was considerably above the zero of the gauge. The favorable state of affairs last fall may have been partially due to accidental causes, which resulted in maintaining such relative height between the Mississippi and the Red and Atchafalaya rivers during the falling stages as to produce a defined current through lower Old River for a long period and so prevent the deposit of sediment, but it is also believed to be attributable to a material extent to influences which are now permanent or favorably progressive. These influences are the improved condition of the Tensas Basin levee system, which has lessened the escape of the crevasse waters from the Mississippi into the Red and Atchafalaya system above Bougere during floods; the growth of trees and the increased deposits on the bars in lower Old River, tending to narrow the channel, which has a tendency to diminish the caving and the trouble resulting from the forcing up of clay lumps and ridges in the bottom of the channel; and possibly the natural filling up of upper Old River, which would have the effect of increasing the flow through the lower Old River when the conditions are favorable to such flow.

The continuation of the levee system south of Bougere, its present terminus, is a matter which should receive early consideration in connection with the improvement of navigation through Old River.

In high water the Mississippi now flows over the western bank and into the basin of the lower Red for the entire distance of 7 miles between Bougere and Union Point, carrying in a large amount of sediment and tending to maintain a condition of equilibrium between the stages of the Lower Red and of the Mississippi and thus to neutralize the current through Old River and hasten the progress of filling up. There are also several smaller gaps between Union Point and the mouth of Red River through which there is a large escape in extreme high water.

The Atchafalaya sill dams are still in good condition and no repairs were necessary during the year. The levee between the dams on the right bank had shown weakness during high water of 1891, requiring some work to stop holes and repair damage caused by sloughing. After the water went down the repairs were completed and a public road crossing constructed over the levee.

When the work was first started a site was leased and depot and store houses established opposite Simmesport. This was convenient to the Atchafalaya sill dams, but too far from the principal part of the work during the construction of the Red River dam and dredging operations in Old Rivers. A new site near Barbres Landing was therefore leased and the storehouses and property moved to it during December and January.

The telephone line was completed during September and has proved of very great value, particularly in the high-water season.

Extensive repairs to six of the large barges and to the steamer Ruby, besides minor repairs to other portions of the plant, were made during the year. Nearly all of the plant was employed on the work at Plaquemine and on levee duty when not needed at Turnbull Island. The dredge Menge was returned to the Third District in February, being required at Vicksburg and no longer available in Old River until the low-water season. The dredge Pah Ute and the tug Comstock were taken to New Orleans for repairs, which are now in progress, and all other parts of the floating plant were removed to New Orleans, where it can be cared for with greater economy.

In June 2,532 tons of rock were borrowed from that stored on Turnbull Island for use on the New Orleans Harbor work, and a like amount was returned to Turnbull Island during April, 1892, the expense of quarrying and delivering having been paid out of the allotment for New Orleans Harbor.

Observations were taken to determine both the extreme low-water and the extreme high-water discharges of the Mississippi at Red River Landing, and of the Atchafalaya at Simmesport. The low-water discharge at and immediately below the Red River dam was also measured,

During the extreme low water a careful survey was made to determine the condition of the Red River dam, and of the river bottom above and below. The field work was under the immediate charge of Assistant Engineer W. G. Price until