MISSISSIPPI RIVER IMPROVEMENT. 



533 



River. According to the laws already stated, 

 a closure of these crevasses ought to wash out 

 shoals formed by them and by contraction 

 deepen the channel. The commission believe 

 that the reduction of the flood-level thus at- 

 tained would ultimately eliminate the necessity 

 for levees above Red River, while below it 

 thev need be maintained at a less height. 



While levees may not be necessary to the 

 securing of a deep channel for navigation, they 

 hasten the work of improvement and are a 

 valuable adjunct. As a protection to life and 

 property along the banks, they are essential. 

 They promote and facilitate commerce by es- 

 tablishing landing-places above the reach of 

 floods. They aid the postal service by protect- 

 ing its carriers, the railroads and common 

 roads, from destruction by floods, as well as 

 give safety and ease to navigation by their 

 influence on the channel. On some of these 

 points the views of two members of the com- 

 mission, not being entirely in accord, are given 

 in a minority report, which differs more in de- 

 gree than in essentials. The breaks in the 

 levee, according to the statement of the com- 

 mission for the reclamation of the alluvial 

 basin of the Mississippi River, amounted in 

 1875 to 8,065,700 cubic yards. Repairs ac- 

 complished since then in Louisiana and Missis- 

 sippi fully equal new cavings in Arkansas and 

 Missouri. To restore the levees to their former 

 height, closing all gaps, would require an ex- 

 penditure of about $2,020,000. The cost of 

 maintenance can not be computed exactly 

 without further data. The commission are of 

 opinion that a continuous line of levee, giving, 

 beyond a peradventure, security from over- 

 flow, would stimulate commerce and foster 

 agricultural and manufacturing interests, bring- 

 ing unprecedented prosperity to the riparian 

 region. 



The Jetty System. This is the plan of im- 

 provement recommended by the commission. 

 Bad navigation is produced by the caving and 

 erosion of the banks, by excessive width, and 

 by bars and shoals as results. The contraction 

 of the water-way to a comparatively uniform 

 width, and the protection of caving banks, are 

 the essential features of improvement. The 

 effect of narrowing the width is to remove 

 shoals and fill up holes, thus giving an even 

 bed, regularizing the discharge and reducing the 

 friction, all of which tend to lower the flood- 

 surface. Of the river below Cairo, it is known 

 by observation that, wherever the low-water 

 width does not exceed three thousand feet, the 

 channel is good ; wherever there is a wide low- 

 river water-way, there are bars and shoals. 



By contracting the low-water channel to an 

 approximate width of three thousand feet, and 

 causing by appropriate works the deposit of 

 sediment on shoals outside of that channel, 

 the improvement can be effected. The works 

 for which estimates are given in the report are 

 expected to maintain a depth of at least ten 

 feet at low water on all bars. The commission 



deprecate attempts to straighten the river or 

 to shorten its course by cut-offs. Borings 

 made in 1875, 1879, and at various other times, 

 confirm the conclusion that the strata forming 

 the river-bed are throughout of a yielding char- 

 acter. If in exceptional spots there is gravel 

 or tough material too heavy for the current to 

 scour, dredging may be required. 



Experience both in Europe and at home de- 

 monstrates that light and inexpensive hurdles, 

 mattresses of brush, or wire nettings, per- 

 meated by the stream, check it sufficiently to 

 produce a deposit of silt. At certain points 

 works of a more solid character are undoubt- 

 edly necessary; but such slender impediments 

 have been used both in the Missouri and Mis- 

 sissippi. By these means, in the area to be re- 

 claimed, silting-basins are established, where, 

 during high water, the arrested current leaves 

 its deposit as it flows onward. The accretion 

 of this deposit may go on through one or more 

 seasons, on varying levels, until the formation 

 is complete. The new bank may be protected 

 by a mattress or revetment. 



An accurate estimate of the cost can not be 

 made until the close of surveys now in prog- 

 ress. Improved methods of construction, de- 

 veloped while the work is under way, may 

 reduce the aggregate amount required. 



The initial works recommended by the com- 

 mission as to be advantageously undertaken 

 during the fiscal year ending June 1, 1881, have 

 an aggregate length of two hundred miles of 

 the shoalest water in the Mississippi below 

 Cairo. The localities are New Madrid, Plum 

 Point, Memphis, Helena, Choctaw Bend, and 

 Lake Providence. Careful and comprehensive 

 estimates are given of the inclusive cost of these 

 improvements, which are thus summed up : 



Estimates for works of improvement during first fis- 

 cal year. 



Initial works for channel contraction and bank pro- 

 tection $4,113,000 



Closing gaps in levees 1,010,000 



Checking enlargement of Atchafalaya 10,000 



Estimate for surveys and expenses of commission for 

 fiscal year ending June 30, 1881. 



For surveys and examinations above and below 

 Cairo, and the necessary salaries and other ex- 

 penses of the Mississippi River Commission .... $200,000 



The report further suggests that Congress 

 arrange some equitable mode of appraisement 

 and purchase of lands and materials needed 

 in the prosecution of the improvements. It 

 further recommends that execution and dis- 

 bursements be not placed in the hands of the 

 commission, but that their duties be confined 

 to the making of plans and modifications, and 

 a general advisory supervision. 



This is a brief synopsis of a report which is 

 at once minute and comprehensive. It is one 

 of the most valuable scientific contributions 

 ever made on the treatment of rivers. A bill is 

 pending before Congress to enable the com- 

 mission to carry forward the plan they have 



