These bridges are all built without draw passages, and are a complete bar to the passage of any boats attempting to navigate the river. The acts of the legislature of the State, of December 26, 1882, and March 3, 1845, declared the stream a navigable one, and provided that bridges and other constructions across the river should be built in such a manner as to allow the safe passage of boats.

(2.) Bends.-As can be seen from the map, and also judged from a comparison of the distances along the river and the valley, the river is very crooked, with bends around which, in a number of instances, navigation will be exceedingly difficult by any but the smallest boats. These obstructions exist mainly in the lower stretch of the river, especially in the vicinity of the 51st, 53d, 54th, and 56th miles from Petersburg, and will necessitate a rectification of the channel in order to render navigation comparatixely easy.

(3.) Cut-offs and outlets.-These exist at a number of points along the river above the 62d mile. The outlets and old river beds will require closure in order to concentrate the water in a single channel.

(4.) Snags.-The river abounds with snags throughout its entire length, brought into it by floods and caving banks. The number of these obstructions per mile is approximately given along with the water depths in the table below. In addition there are numerous leaning trees along both banks that will have to be cut down, and the banks cleared back for a space of 50 feet, where there is shown any tendency towards caving.

(5.) Shallow water.-For the purpose of showing the minimum, average, and maximum depths at low water through each mile of measured river, the following table is inserted:

Only 6 miles in the preceding table of soundings show average minimum depth at low water exceeding 3 feet, and 15 miles show minimum depth of 1 foot or less. I have no data to determine the length of the low-water season, but it is evident that there must be several months in the year when there is not sufficient depth for navigable purposes.

So far as ascertained but one effort has been made to afford water

transportation facilities to the Upper Sangamon. A company was organized, and chartered by the State legislature in 1843, for constructing a canal from the Illinois River near Beardstown to the Sangamon, in the vicinity of Miller's Ferry, thus avoiding the tortuous channel of the river, but nothing was done toward the actual construction of the work. Boats have at times ascended to Petersburg, but since the advent of the railroads nothing has run upon the river except small boats employed in getting out timber and railroad-ties.

Existing transportation facilities may appropriately be noticed. In Mason, Cass, and Menard counties there are about 185.9 miles of broadgauge railroad operated by the Chicago, Burlington and Quincy, Chicago, Alton and Saint Louis, Wabash, Saint Louis and Pacific, and Ohio and Mississippi Railway Companies. The first three are competing routes for Chicago and Saint Louis business, and the last two for eastern traffic, with very inferior facilities therefor. One mile of railroad to each 6.56 miles of area of the three counties thus supplied is about the average for the State. On railroads crossing Sangamon below Petersburg there are within its valley five regular stations and a coal siding. Neither of these is more than 1.5 miles from flooded bottoms, on which few tenants dwell. These stations average 11 miles apart along the valley, and are between 1.3 and 2.7 miles from the river. The extreme direct distance of any farm in Sangamon bottoms below Petersburg from a railroad depot is 9 miles from section 2, township 19, range 11 eastward, to Saidora, in Mason County.

Only on section 25, township 19, range 11, does high ground near the river below Miller's Ferry render the stream at all stages accessible to traffic, though such conditions favorable to business prevail at many localities above the latter. Excepting the bridges described, a rope ferry, three fords, and a portable saw-mill, no results of commercial or industrial enterprise exist on the banks of the Sangamon River below Petersburg Coal Company's shaft. Upon 38.5 valley miles but three river crossings are safe for vehicles during medium and low-water stages, and only a passage by rope ferry is practicable for them during ordinary floods.

It is evident from the table of channel depths as given above that there can be no navigation upon the Sangamon at the lowest stage of water, even if all the obstructions were removed. It was expected that possibly the pool caused by the lock and dam now in course of construction at La Grange, on the Illinois River, would give back water some distance up the Sangamon, but it is found from the levels that this will not extend more than 6 miles above the mouth, and therefore be of little aid in maintaining a good navigable depth of water.

COMMERCIAL STATISTICS.

The three counties adjacent to the section of the river in question are Menard, Mason, and Cass, and produced during the year 1882 the following:

In addition, there were large quantities of coal produced, the estimate yield of which, in Menard County, for 1883, was 208,000 tons.

Of course, it is not presumed that the above products would be shipped via the river, but it is believed that a strip of country bordering on the river would avail itself of the advantage of water transportation could the river be improved.

The character of the stream, were the natural obstructions removed, would allow the passage only of a class of small boats or barges at or above a 4-foot stage, but the improvement would be of no avail in the present condition of the bridges crossing the river. The estimated cost of removing the snags, bars, &c., closing outlets, and rectifying the channel at certain bends, is $60,000.

Very respectfully, your obedient servant,

The CHIEF OF ENGINEERS, U. S. A.

W. H. H. BENYAURD,
Major of Engineers.

HH 8.

PRELIMINARY EXAMINATION OF ILLINOIS AND DES PLAINES RIVERS BETWEEN LA SALLE AND JOLIET, ILLINOIS.

UNITED STATES ENGINEER OFFICE,

Chicago, Ill., September 2, 1882. GENERAL: I have the honor to present the following report in regard to the proposed survey of the Illinois and Des Plaines rivers from Joliet to La Salle, Ill., as provided for in the river and harbor act of August 2, and assigned to my charge by letter of August 11.

Several surveys have been made of the route by the State and by the General Government, and I have not deemed it necessary therefore to make a personal examination of the stretch of river in question, in order to report upon the necessity of an instrumental survey.. I have examined the maps and consulted the reports and other sources of information, and deem it necessary to make survey, estimates* for which work are presented herewith.

The necessity of the improvement derives its importance from several considerations. The State has improved the river for ship naviga tion from La Salle to Copperas Creek, and the Government is now engaged in continuing the improvement thence to the mouth. I am directed to report upon the cost of enlarging the Illinois and Michigan Canal, which extends from Lake Michigan to La Salle. This work, if ever carried on, will give through navigation for large vessels from the lake to the Mississippi. The canal runs in close proximity to the river the entire distance from Joliet to La Salle, and in making up the esti mates for the enlargement of the canal it will be necessary to discuss whether or not it will be more economical to enlarge the canal between those two points, or to improve the river and abandon the other. Very respectfully, your obedient servant,

Brig. Gen. H. G. WRIGHT,

Chief of Engineers, U. S. A.

W. H. H. BENYAURD,
Major of Engineers.

Omitted.

SURVEY OF ILLINOIS AND DES PLAINES RIVERS BETWEEN LA SALLE AND JOLIET, ILLINOIS.

UNITED STATES ENGINEER OFFICE,

Chicago, Ill., March 5, 1884.

GENERAL: I have the honor to present the following report upon the survey of the Des Plaines and Illinois rivers from Joliet to La Salle, with estimates of cost of improvement, as provided for in the river and harbor act passed August 2, 1882.

The survey party, under the charge of Mr. George Y. Wisner, assistant engineer, was not sent into the field until the 1st of October, 1883, as it was deemed better to wait and take advantage of the very lowest stage of water that could be found, not only as a matter of economy, but as affording the advantage of obtaining the fullest information when the rivers were in their worst condition, upon which state it was necessary to base the proper plan of improvement.

The survey was commenced at Dam No. 1 on the Des Plaines River, at Joliet, and continued to a point on the Illinois River near La Salle, where the Illinois and Michigan Canal enters the pool created by the lock and dam constructed by the State at Henry.

The rivers have an average width of about 600 feet, with banks from 8 to 23 feet in height above low water, so that within ordinary stages the stream flows within fixed banks. The oscillation between high and low water is about 15 feet, though a height of 23 feet has been recorded, occasioned by an ice-gorge.

The fall in the low water surface between the points indicated above, a distance of 64.2 miles, is 100.25 feet. This fall is not, however, equally distributed over the entire distance, but occurs at various points, principally at the ripples separating the different pools, and amounting in some cases to 10 feet per mile.

It is evident, after consideration, that the only feasible plan to render the stream navigable is to slackwater the entire distance. This can be accomplished by the construction of nine locks and dams, the cost of which depends upon whether the plan adopted shall be in conformity with that now in course of execution for the lower Illinois River, or whether the locks shall be of the size recommended for the Hennepin Canal. In addition to the requisite locks and dams, the plan also contemplates the construction of a short canal at the falls of Joliet, and one at Marseilles. The location of the various structures and the two canals were fixed upon, so that there should be no conflict between the United States and persons owning valuable manufacturing interests along the river, where water power is used. Certain low lands will necessarily be submerged if the plan be carried into execution; very little of it, however, is of any considerable value, and can very easily be estimated for. On this point the notes of the survey are very complete, and the maps are constructed showing the contours at every 5 feet elevation, so that the amount and character of the land submerged at any height above low water can readily be determined.

The Illinois River, below the termination of the present survey, has been rendered navigable by the State by the construction of the locks and dams at Henry and Copperas Creek. Two additional locks are now in course of construction by the Government, which will carry the navigation through to the Mississippi. All the locks are 350 feet long between gates, by 75 feet wide, and adapted for the passage of the largest size steamers navigating the river.

With the improvement of the river now in question carried on, navi

gation will be brought to within 33 miles of the lake, and this stretch can be opened by improving the Des Plaines higher up, and by enlarging the present Illinois and Michigan Canal. In the report I have estimated for locks of the same size as those on the lower river, and with the same lift-7 feet. At the same time, as the question of the construction of the Hennepin Canal and the enlargement of the Illinois and Michigan Canal is under consideration, I have had other estimates made for locks of the same size as those recommended for these works. As stated in my preliminary report under date of September 2, 1882, I had intended instituting a comparison between the cost of enlarging the Illinois and Michigan Canal between Joliet and La Salle and that of improving the rivers between the same points; but as the survey of the latter was not at that time authorized, I merely confined my report on the Illinois and Michigan Canal to the cost of enlargement throughout its entire length, and without making any change to the river route. With the data furnished by the present survey, it has been ascertained that the cost of the enlargement of the canal for the middlesized locks is less than what the improvement of the river would cost for the same class of works, while in the case of the larger locks the expense would be greatly in favor of the river route. The additional cost of the river route in the first instance would be offset by the lesser amount that would be required for maintenance, repairs, &c., as the long line of canal, with its aqueducts, feeders, weirs, &c., would be a constant source of expense. The river route has also the advantage, when it is considered that we have navigation on a stream 600 feet wide instead of the narrow channel of the canal.

Looking at the matter in an engineering point of view, it is difficult to understand what led originally to the construction of the canal, rather than the improvement of the natural channel of the river. Should the Illinois and Michigan Canal be accepted by the Government, and its enlargement undertaken, that part between Joliet and La Salle should be abandoned and the river route between these points adopted.

Another point in the contemplated improvement, or in the acceptance of the Illinois and Michigan Canal, demands notice. As before mentioned, two locks and dams are in course of construction on the lower river by the Government, above which there is a stretch of 88 miles of river improved by and now under the control of the State. Should the United States continue the improvement between Joliet and La Salle, there will then be a part of the river forming a link between the upper and lower portions over which the State now exercises control, and upon which tolls are collected for the passage of boats through the locks. The act of the legislature of the State ceding the Illinois and Michigan Canal did not, as I understand, include the locks and dams at Henry and Copperas Creek, but only the canal as originally constructed.

The estimated cost of improvement, with locks having chambers 350 feet long and 75 feet wide, is $3,433,562, and for the size of locks adopted for the Hennepin Canal, 170 feet by 30 feet, $1,975,446.

There is transmitted herewith the report of Mr. George Y. Wisner, assistant engineer, to which reference can be made for details of sur vey, &c.

The maps will be completed in the course of the present month and forwarded to the Department.

Very respectfully, your obedient servant,
W. H. H. BENYAURD,
Major of Engineers.

To the CHIEF OF ENGINEERS, U. S. A.