required. Data can only be obtained during a considerable period of actual test. Should the work of improvement suggested, or any part thereof, be undertaken by the United States, the act of Congress pro viding for it will possibly be explicit enough, as to extent of work designed, to enable the engineer to estimate for amounts required each year for carrying on the work to advantage. K 14. SURVEY OF TANGIPAHOA RIVER, LOUISIANA. A preliminary report on this survey was forwarded to the Chief of Engineers February 12, 1879, as follows: PRELIMINARY REPORT. UNITED STATES ENGINEER OFFICE, New Orleans, February 12, 1879. GENERAL: I have the honor to submit the following preliminary report on a survey of the Tangipahoa River, as provided for by act of Congress approved June 18, 1878. The survey was commenced on the 27th of January last, at the town of Amite, in the State of Louisiana, and concluded on the 7th of February, at the mouth of the river. The stream was meandered with transit and stadia, and obstructions to navigation located, where of special importance, by use of the same instruments. Other obstructions were approximately located, and the character of all was ascertained. The length of that portion of the stream surveyed is 53 miles. Throughout the upper portion covered by the survey the stream flows through a heavily-timbered bottom-land, averaging about 2 miles in width, and bordered by what is known as "piney-woods lands," which is above overflow. The lower 10 miles of the stream runs through the swamp bordering Lake Ponchartrain, also heavily timbered. The bed of the stream is composed of sand and gravel, and the bars which obstruct low-water navigation are formed of this material. As the survey was made at a quite low stage of the river, it was possible to examine these bars well, and it was found that most of them were due to sunken logs and snags that had formed a nucleus for the bars. It is thought that removal of these logs, &c., will cause the bars to disappear. There are 1,856 snags and fallen trees in this section of the river which serve to obstruct navigation; also 660 overhanging trees and 1 bridge, which it would be necessary to convert into a draw-bridge to accommodate steam or sail navigation. There is one island chute that it would be desirable to have closed. The stream averages about 100 feet in width, and it is thought can be given a least depth (low-water) of about 34 feet, which would be sufficient for all purposes and as much as can be carried across the bar at its mouth. It is estimated that to effect this improvement would cost about $200 per mile, or a total of $10, 700. The trade to be benefited is very considerable. The timber along the valley of the stream is very valuable, and, even in the present_obstructed condition of the stream, quantities of it are rafted to the New Orleans market. Lumber, cotton, poultry, vegetables, and fruits form important items of production along the stream, and its opening to navigation would greatly cheapen the cost of getting these to market. In 1871, by order of Congress, and under direction of the War Department, there was made a survey of the lower portion of this stream (see Report of the Chief of Engineers for 1871, Appendix N 10), which resulted in appropriation and in contract for improvement. This improvement is said to have been of great benefit (comparatively), but since, other obstructions have been brought down into this portion of the river in the shape of snags and cypress logs. The cost of the work was very little, the amount of work done considered, and this was owing to the interest taken in it by those who most desired it done, and done well. (See Report of the Chief of Engineers for 1873, Appendix Q 5.) The same interest is manifested above this portion of the river, as shown by the cheerful and volunteered assistance given to the survey party. This office sent out on the survey one assistant engineer and the necessary instruments; parties in Amite and along the river provided for all other assistance and expense. Mr. H. S. Douglas, assistant engineer, who had charge of the survey, reports that he was everywhere treated in the most hospitable manner and provided with all the assistance he desired. Charts of the survey will be forwarded with my final report at the close of the fiscal year. The report of Assistant Douglas will also be forwarded, giving details. Very respectfully, your obedient servant, Brig. Gen. A. A. HUMPHREYS, Chief of Engineers, U. S. A. Ć. W. HOWELL, Report of Assistant Engineer H. S. Douglas, who had charge of the survey, is now given in addition and charts forwarded. REPORT OF MR. H. S. DOUGLAS, ASSISTANT ENGINEER. UNITED STATES ENGINEER OFFICE, New Orleans, April 24, 1879. CAPTAIN: In obedience to your orders, I left New Orleans January 27, and proceeded to Amite, La., for the purpose of making a survey of a portion of the Tangipahoa River, and have the honor to submit the following report: I arrived at Amite on the 27th, and thanks to the valuable assistance tendered by Mr. B. D. Gullett, I was enabled to organize my party, complete my outfit, and commence field operations the day of my arrival. My party and outfit consisted of 4 men and 4 boats. The initial point of the survey was taken at what is known as Connor's Bridge, a point on the river about 14 miles from the town of Amite. From this point the stream was meandered with transit and stadia, and all important obstructions were located with these instruments. The method of operations was as follows: A suitable position was selected for stadia No. 1, the transit was placed in a position to sight both forward and back, and set up on magnetic meridian; the distance and bearing to stadia No. 1 were then read; also the distance and bearing to stadia No. 2, which was in a convenient position ahead of the transit. The transit was then moved to a point beyond stadia No. 2 and set up in the same manner as before; the readings and bearings then taken back to stadia No. 2 and forward to stadia No. 1 (meantime sent on ahead), and so on, repeating the same operations every time the instrument was moved. Soundings were taken from the boat while moving from station to station and put down at their location on the field plat. None were taken below Wells' Ferry, as there is every where more water than on the bar at the mouth of the river. The length of that portion of the river surveyed from Connor's Bridge to its mouth at Lake Pontchartrain is 534 miles. The time occupied was 12 days, from January Z to February 7, inclusive. The river remained at ordinary low-water during the survey, and in consequence a great many obstructions were observed and noted that otherwise would have escaped observation. Average high-water is from 16 to 18 feet above the plane of reference used on the survey. During low-water the river is fed almost entirely by springs, which keep it up to an average stage even during long droughts. The stream meanders a heavily-timbered valley, or bottom-land, subject to overflow at high-water, which is terminated on either side by high "piney-woods” lands, not subject to overflow. This valley varies from 1 to 2 miles in width. The bed of the river is composed almost entirely of sand and gravel, clay botto occurring in but two places, noted on the accompanying chart. The bars are a mixture of sand and gravel, which would probably wash out but for the presence of numerous sunken snags. The removal of these snags will allow the bars to wash out to a much greater depth than they now have. Except where the land has been cleared for cultivation the banks are heavily-timbered to the water's edge, and most of the obstructions occur in the bends where the banks cave, and allow the trees to fall in. The fall of the valley to tide-water is very rapid, and in consequence the stream is quite crooked, thereby dividing the fall through a longer distance, lessening the cur rent, and making it practicable for navigation. The greatest current velocity ob served did not exceed 2 miles per hour. The average width of the stream is about 100 feet. Tide-water reaches as far up as Wells's Ferry, and from that point to its mouth, at Lake Pontchartrain, the river partakes more of the character of a bayou. It is deep from bank to bank, and at low-water the current is scarcely perceptible. For the last 10 miles of its course the river flows through the cypress swamp bordering Lake Pontchartrain. Cut-offs have been tried in several places with the intention of shortening the river, and so improving the navigation; but in this they have had rather a contrary effect. as the increased velocity of the current causes the banks to cave and the river to fill with obstructions. The accompanying table shows that in those miles where cut-offs have been made the number of snags is greatly increased. In several places island chutes, or "little rivers," as they are called, leave the main stream, and sometimes flow independently for nearly a mile before returning. Whenever this occurs the number of obstructions in the main river is greatly increased and, of course, the depth of water decreased. The closure of the majority of these "little rivers," or island chutes, will be necessary to the permanent improvement of the river. Under the head "Miscellaneous," in the table, are given some obstructions requir ing a fuller description. At of a mile below Connor's Bridge is a "fish-trap," consisting of 2 parallel rows of light piles, from 4 to 6 inches in diameter and placeda bout 5 feet apart. They can easily be removed, being driven into sand and gravel. There is another "fish-trap" at the end of the second mile, which can be removed as easily as the first. On the tenth mile a "little river" leaves the main stream, carrying off fully of its volume. This, as well as all others like it, it would be absolutely necessary to close. On the eleventh mile are the remains of the Independence Bridge, consisting of two clusters of piles. These it may not be necessary to remove, as there is an open channel 50 feet wide between them. On the twentieth mile are 7 large trees standing in the channel, which it would be necessary to either remove or cut a channel around; also, a place where a raft of snags and drifts have collected, allowing a clear channel of but 18 feet in width. On the twenty-second mile is Dunnington Bridge, which would either have to be removed or converted into a draw. On the thirtieth mile is a sunken flatboat, with 42 inches of water over it at lowwater. Its removal is not absolutely necessary. Owing to the nature of the river-bed, the removal of the snags will not be difficult. They would yield easily to the power of a snagboat, as there is no tenacious clay to hold them. In the column of "least depths," the figures given indicate the least depth on the shoalest bar, and these are generally of small extent. The closure of the "little rivers," or island chutes, can best be accomplished by running into them the snags, overhanging trees, &c., removed from the main river. It would be desirable, also, to close such cut-offs as have not already become the main channel. It may not be necessary to convert Dunnington Bridge into a draw, as parties interested in it state that in case the stream is improved for navigation they, themselves, will remove the bridge. The following estimate of removing the obstructions to navigation in the Tangipahoa River will give a navigable channel with a least depth of 42 inches to Dunnington Bridge, and a channel with a least depth of 24 inches to Connor's Bridge. Forty-two inches is all that can be carried over the bar at the entrance to the river. The total number of snags is 1856 and of overhanging trees, 660. The greater part of these will be found in the first 38 miles of river, as the last 15 are almost clear. If a smaller amount than that asked for is appropriated, I would respectfully suggest that it be expended on that portion of the river below the remains of the Independence Bridge. An inspection of the accompanying chart will show the advisability of this. In 1871 a schooner was built near this bridge, the dimensions of the boat being, length, 60 feet; breadth of beam, 18 feet; and draught, 18 inches. This boat was taken down the river from this point without difficulty, except from snags at lowwater. The trade to be benefited is important, and would be materially increased by the opening of the stream to navigation. Valuable timber, principally cypress and pine, abounds in the valley of the stream, and a large business is done in rafting this to the New Orleans market. This rafting is, however, confined to the lower portion of the river, as it cannot be carried on above on account of the obstructions. Large quantities of cotton, sugar, vegetables, fruits, and poultry are produced in the country bordering the stream. Sugar-raising has lately become a prominent industry. The cost of getting these products to a market would be greatly lessened by the improvement of the river. The greatest interest is taken by the residents of the country in the proposed improvement, and every assistance in making the survey was cheerfully volunteered. Your assistant and his party were every where treated in the kindest and most hospitable manner. Further information will be found on the two charts accompanying this report, which are plotted on a scale of 1 to 5,000. That portion of the river from Wells's Ferry to the mouth was reduced from the survey of 1871 and corrected to date. Very respectfully, your obedient servant, Capt. C. W. HOWELL, Corps of Engineers, U. S. A. |