MISSISSIPPI RIVER

the u.s. govt. continued work on the various enginecring projects connected with the mississippi and its tributaries, the missouri and ohio, during the years 1910-26. on the upper mississippi the reservoirs at the headwaters numbered six, namely winnibigoshish, leech, pokegama, sandy and gull lakes and pine river, which have a combined storage capacity of nearly 95,000,000,000 cubic feet. between st. paul and minneapolis the original plan for two low dams has been changed to one high dam (36 ft.) with provision for water-power development. the project was in 1925 prac- tically completed, and the power development was leased to henry ford for a large assembling plant now in operation. on the main upper mississippi river the plan is to obtain a six-foot depth by contracting the width by brush and stone wing dams, by closing chutes and by revetting banks where neces- sary, supplemented by dredging. special treatment by locks and dams is given to two localities—rock island rapids and des moines rapids. at the former point a lock and lateral canal at leclaire, ia., overcomes the fall of the upper rapids, and a lock and lateral canal at moline, ill., overcomes the fall of the lower rapids. the project at this point 1s practically com- pleted. the open channel through both rapids is still maintained. at des moines rapids (keokuk) private interests have built a water-power dam, concentrating the entire fall of the former canal and locks into a single lock. the project is completed. there is little navigation on the upper mississippi, but prospects for revival appear encouraging. on the middle mississippi between the missouri and the ohio, the plan is for six-ft. depth above st. louis and eight ft. below, obtained by contraction and by closing chutes with permeable pile dikes, and by revetting banks where necessary, supplemented by dredging. in that part of the river below st. louis there is considerable revival of navi- gation. on the lower mississippi river, from the ohio river to the passes, the plan is for nine-ft. depth, to be obtained by revetting banks, supplemented by dredging. in tor7 congress passed the flood control act providing a certain amount of money to be expended by the mississipp1 river commission for improvingthe river between cairo and head of the passes, and for flood control between rock island and the passes. in 1923 a second flood control act extended the commission’s jurisdiction to all tributaries between rock island and the passes, in so far as they are affected by floods in the mississippi river. as regards the passes, or mouths of the river, the plans adopted in 1902 having proved inadequate, additional works were authorised in 1916, which have secured a channel through southwest pass with a controlling depth of not less than 35 feet. the controlling depth in south pass is approxi- mately 34 feet. the missouri—on the part of the river above kansas city there is no definite depth to be attained, the project being simply to remove snags and boulders, leaving the natural depth and width of channel, and to revet the banks at certain localities where encroachment threatens great damage. on this part of the river there was in 1926 little commerce. on the section of the river below kansas city, there is a definite six-ft. project, adopted by congress in 1910 and being regularly carried out. here too there was little navigation, but prospects for revival were encouraging. the ohio —a comprehensive project for canalising the ohio so as to provide a channel nine ft. deep was adopted by congress in 1910. slight modifications have since been authorised. as it stood in 1926, the project provides for 50 locks and dams, all of the movable type, except the one immediately below pittsburg, pa., which is a fixed dam, completed in 1921, for the purpose of improving conditions in pittsburg harbour. of these dams 42 were completed and in operation, and the other eight were under 936 construction, with the probability that the project will be en- tirely completed by 1929. the type of dam, together with the relatively low head, does not lend itself tothe development of power on a commercial scale. there is one exception to this general statement, at louisville where the existing navigation dam is being replaced by a power navigation dam eight ft. higher, thereby creating a head of 37 feet. the total tonnage shipped wa the ohio river in 1924 was 10,867,000 tons of which 514°% was coal. commerce on the river has been increasing steadily, particularly on the completed part and many terminals for handling coal have been constructed. a destructive flood occurred in march 1913, and, on that part of the river between wheeling and cincinnati and on the tributaries entering from the north in this reach of the river, higher flood stages were reached than had been recorded prior to that date. the flood was particularly destructive in the miami valley, and, to guard against a recurrence, extensive flood-control works have since been constructed. 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