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position (less 20°) with its lower edge resting against the sill of the pass and its middle braced in position by the prop. The reverse of this operation constitutes the lowering of the wicket, i. e., the wicket is first pulled slightly upstream, which has the effect of disengaging the prop from its step; once out of its step the prop slides downstream in its cast-iron groove and permits the wicket to fall and, in falling, to assume a horizontal position on top of the pass foundation.

Bear traps and Chanoine weirs.-The function of the bear traps and other weirs is to regulate the pool levels within certain limits without having to resort to the lowering of the wickets in the navigable pass. The bear-trap weirs are structures of iron, steel, and wood, in two leaves, hinged at their outer ends. The lower leaf of each bear trap is a hollow structure like a pontoon, into which air may be forced to increase its buoyancy by displacing the water. By the united effect of this buoyancy and the pressure due to hydraulic head caused by raising the wickets in the navigable pass, the lower leaf rises into position, raising the upper leaf. When the bear trap is up it forms an A-like structure which was supposed to bear some resemblance to the deadfall used in trapping bears, hence the name "bear trap. The bear traps are usually two in number and are operated quickly and independently of each other to form a waste weir, so that the flow of water past the dam may be regulated with great nicety. Besides the bear-trap weirs, most of the Ohio River dams have a section of Chanoine weir, which is merely a repetition of the navigable pass, with its sill placed at a higher level and having, in consequence, wickets of shorter length. The Chanoine weir may be used like the bear traps to regulate the pool levels, but it is not essential to the operation of a dam.

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Dams Nos. 21, 22, 23, 24, 25, 27, 30, 39, 43, 44, 48, 52 and 53 have an automatic wicket of special construction designed by Mr. Guy B. Bebout, assistant engineer, whose name it bears. The Bebout wicket is used as a substitute for the Chanoine wicket in portions of the navigable pass and Chanoine weirs; also, in the case of Dams 21, 30, and 39, as a substitute for a bear trap.

Winding engines, air and oil jacks, boilers, etc.-Essential to the operation of the locks and bear traps are the devices used in opening and closing the lock gates and the filling and discharge valves. These devices are mostly operated by air or oil compressed by water power plants located on the river walls of the locks. Steam, gas, or Diesel engines or electric motors are maintained at these dams as auxiliary plants and used only when water power is not available.

NAVIGABLE DEPTH

Slackwater navigation to a least depth of 9 feet is available throughout the year (except during times of running ice) from Pittsburgh, Pa. to Dam No. 53, a distance of about 962.6 miles, or to a point 18.4 miles above the mouth of the Ohio. For this last stretch of 18.4 miles the project contemplates an open dredged channel with a depth not less than 9 feet, which is generally maintained.

As a means of indicating to the users of the river the navigable depths available in the various pools, gage readings are displayed on bulletin boards attached to the power houses of all Ohio River dams, figures of sufficient size to be easily read with binoculars from a dis tance of 1,000 feet or more being employed.

At fixed dams, and at movable dams when they are up and the locks open to navigation, the gage readings indicate the elevation of the pool impounded by the dam next below, 9 feet being uniformly assumed as the elevation of normal pool. For example, a bulletinboard reading of 8.7 feet indicates that the lower pool at the dam is 0.3 foot below normal. Such readings are preceded by the letters "N. P." (white letters on green background).

When movable dams are down and navigation is using the navigable pass, the gage readings displayed on the power-house bulletin board indicate the depth available over the pass sill at the dam. Such readings are preceded by the word "Pass" (white letters on scarlet background), showing that the readings are referred to the top of the navigable pass sill as a datum plane. The "Daily River Bulletins" distributed by the U. S. Weather Bureau at certain Ohio River cities publish gage readings identical with those displayed on the Bulletin Boards maintained at the dams.

LOW-WATER PERIODS

Considering the river as a whole, the low-water periods are likely to occur between July 1 and December 1, but this rule is not invariable, as low water may begin in April or May, to be followed by rather high stages in June, July, or August; also the fall rises sometimes begin in September and continue for the remainder of the season. The stages in the various sections of the river also vary, it being frequently necessary to lower the movable dams in a certain section while those above and below may remain up.

Special information concerning gage readings can be obtained from the following sources:

On the Ohio River:

Pittsburgh, Pa., to Wheeling, W. Va..

Wheeling, W. Va., to Point Pleasant, W. Va....
Point Pleasant, W. Va., to Kentucky River....
Kentucky River to Hawesville, Ky.
Hawesville, Ky., to Wabash River.

Wabash River to mouth of Ohio River..

1930 LOW WATER

U. S. Weather Bureau at

Pittsburgh, Pa.
Parkersburg, W. Va.
Cincinnati, Obio.
Louisville, Ky.
Evansville, Ind.
Cairo, Ill.

The flow of the Ohio River was, in general, lower during the fall of 1930 than it has been at any time since stream flow records have been kept. Although the flow dropped to unprecedented low levels, pool elevations on the Ohio River were maintained close to normal throughout the system, and no serious interruptions to traffic resulted.

FLOODS

High-water stages of 50 feet or more in the Ohio River at Cincinnati, Ohio, usually occur in January, February, and March, but at least 1 stage above 60 feet occurred in December 1847; 1 above 55 feet occurred as late as April 4, 1908; and 1 summer flood exceeding 55 feet occurred August 6, 1875. Taking into account the 2 isolated years, 1832 and 1847, and the 76 years continuous record from 1858 to 1933, inclusive, the river at Cincinnati has reached flood stages as follows:

Over 50 feet and less than 55 feet, 37 times in 29 years (not consecutive).
Over 55 feet and less than 60 feet, 22 times in 21 years (not consecutive).
Over 60 feet and less than 65 feet, 8 times in 8 years (not consecutive).
Over 65 feet and less than 70 feet, 3 times in 3 years (not consecutive).
Over 70 feet and less than 72 feet, 1 time in 1 year.

Navigation during extreme flood stages (52 feet or greater at Cincinnati) is attended by great danger and should not, as a rule, be undertaken without the guidance of an experienced Ohio River pilot. Not only is the headroom under bridges and aerial-wire crossings greatly diminished, but the real river channel is often difficult to follow, especially during times of fog.

THE FLOOD OF MARCH 1913

The most serious flood of recent years on the Ohio River occurred during the early spring of 1913, when the Allegheny, Beaver, Muskingum, Scioto, the two Miamis, the Wabash, and some other streams, mostly from the north, contributed an almost unprecedented run-off from the States of Pennsylvania, Ohio, Indiana, and Illinois. A comparison of the flood of 1913 with the great flood of 1884 shows some vagaries. The records of the United States Weather Bureau indicate that at Pittsburgh the flood stage of 1913 was lower than that of 1884 by 2.9 feet; at Parkersburg, higher by 5 feet; at Cincinnati, lower by 1.3 feet; at Louisville, lower by 1.8 feet; and at Evansville, higher by 0.4 foot.

RUNNING ICE, ICE HARBORS, ETC.

Running ice and ice gorges may occur during the months of December, January, or February, but seldom later.

The ice gorges are at times extremely dangerous to navigation. For the purpose of aiding navigation, the United States has constructed concrete ice piers at the following points: Middleport, Ohio, 251.7 miles below Pittsburgh; Gallipolis, Ohio, 269.5 miles below Pittsburgh; Maysville, Ky., 408.5 miles below Pittsburgh; Cincinnati, Ohio, 469.7 miles below Pittsburgh; and Sayler Park, Cincinnati, Ohio, 482.7 miles below Pittsburgh. Each pier consists of 3 sections rising to a height of from 30 to 39 feet above low water. A boat sheltered behind such piers may safely withstand the break-up and runout of the ice. Timber ice piers, controlled by private parties, are located at various points along the river, principally in the vicinity of Cincinnati and immediately below. The United States has no control over these private piers except to see that craft moored below them do not obstruct the channel.

Safe havens in time of running ice may usually be found in the mouths of Ohio River tributaries, etc., as follows:

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In addition to the havens formed by ice piers and tributary streams there are many localities where sharp deflections in the trend of the open river banks provide mooring grounds of comparative safety. Information concerning such natural havens can be given only by experienced Ohio River pilots,

NO WATER CONNECTION WITH THE GREAT LAKES

Owing to the damaged condition of the Ohio Canal near Dresden, Ohio, and between that point and Cleveland, there is at present (1934) no continuous water connection between the Ohio River and the Great Lakes via the Muskingum River; other connections, such as those which formerly existed by way of the Beaver and Little Beaver, Scioto, Miami, and Wabash Valleys, have long since been abandoned or destroyed.

AVAILABLE MAPS AND CHARTS

Charts of the Ohio River survey of 1911-14 (revised 1929), from Pittsburgh to the mouth, consisting of 1 index sheet (scale: 1 inch to 8 miles) and 280 charts (scale: 1 inch to 600 feet), each measuring over all 24 by 30 inches, may be purchased for 25 cents each at the United States Engineer Office, 429 New Post Office Building, Louisville, Ky., the free distribution thereof being held to be prohibited by act of Congress.

Payments must be made before charts are sent, and if made by mail, must be by postal or express money order payable to the order of United States District Engineer, Louisville, Ky.

A detailed descriptive list of these charts may be obtained without charge upon application to the Office of the Chief of Engineers, United States Army, Washington, D. C., or to the United States Engineer Office at Louisville, Ky.

Maps of the Ohio River flood plain (scale: 1 inch to 2,000 feet, with 20-foot contours) may also be secured from the United States Engineer Office at Louisville, Ky., at a cost of 40 cents each. These maps (size 271⁄2 by 42 inches) were prepared in 1929-31 and cover in 39 sheets (including an index sheet) the section of the river from 6 miles above Louisville, Ky., to the mouth.

DOCKS, MARINE WAYS, AND BOAT REPAIRS

Repairs requiring the removal of the boat from the water may be made at the following localities:

Monongahela River:

Braddock, Pa., floating dock.

Dravosburg, Pa., floating dock.

Elizabeth, Pa., marine ways.

Clairton, Pa., marine ways.

Floreffe, Pa., marine ways.

Alicia, Pa., marine ways.

Crucible, Pa., floating dock.

Pittsburgh, Pa., smaller boats and barges may be repaired at floating docks at Glenwood, South Twenty-second Street, and West Carson Street.

Kanawha River:

Point Pleasant, W. Va., two floating docks.

Plymouth, W. Va., floating dock.

Dana, W. Va., marine ways.

Ohio River:

Pittsburgh, Pa., north side, floating dock, Pearson and Lysle landings.
Neville Island, Pa., marine ways (cradle ways).

Marietta, Ohio, United States docking caisson.

Parkersburg, W. Va., floating dock.

Middleport, Ohio, marine ways.

Cincinnati, Ohio, United States marine ways near Dam No. 37.
Madison, Ind., marine ways.

Louisville, Ky."

One United States dry dock, Louisville & Portland Canal.

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One floating dock. Used for repair work on towboats and barges. Evansville, Ind., one marine ways (skid ways). For repair work and construction for wood barges only. Available 135 feet.

Paducah, Ky.:

One marine ways (cradle ways). Used for repair and new construction for steel and wooden vessels.

One floating dock. Used for repair work on towboats and barges, wooden vessels only. Capacity 275 tons.

One floating dock. Used for repair work on owner's barges only. Mound City, Ill., one marine ways (cradle ways). Used for repair work and new construction, wood and steel vessels.

Kentucky River:

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Spottsville, Ky., one skid ways. Used for repairing and building wooden barges up to 120 feet in length.

Contracting and industrial plants have installed launching ways, exclusively for the construction of boats and barges, at the following localities:

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Repairs to engines and boilers, purchase of rope, pipe, and fittings, and general boat supplies, including ice and meat, may be made at the following points: Pittsburgh, Pa.; Wheeling, W. Va.; Marietta, Ohio; Parkersburg, W. Va.; Point Pleasant, W. Va.; Gallipolis, Ohio; Huntington, W. Va.; Ashland, Ky.; Ironton, Ohio; Portsmouth, Ohio; Maysville, Ky.; Cincinnati, Ohio; Madison, Ind.; Jeffersonville, Ind.; Louisville, Ky.; New Albany, Ind.; Owensboro, Ky.; Evansville, Ind.; Henderson, Ky.; Paducah, Ky.; and Cairo, Ill.

FUEL

Coal usually may be obtained at Pittsburgh, Pa.; Wellsburg, W. Va.; Wheeling, W. Va.; Bellaire, Ohio; Moundsville, W. Va.; Pomeroy, Ohio; Huntington, W. Va.; Cincinnati, Ohio; Madison, Ind.; Jeffersonville, Ind.; Louisville, Ky.; New Albany, Ind.: Evansville, Ind.; Caseyville, Ky.; Paducah, Ky.; and Cairo, Ill.

Fuel oil for Diesel boats may ordinarily be secured at Pittsburgh, Pa.; Steubenville, Ohio; Wheeling, W. Va.; Huntington, W. Va.; Cincinnati, Ohio; Louisville, Ky.; Evansville, Ind.; Paducah, Ky.; Metropolis, Ill.; and Cairo, Ill.

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