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be $485,300, to State and local governments $16,300, and to private individuals nearly $2,000,000. Of the total cost during this period, approximately 50 percent is carried by the Federal Government; after this period, approximately 80 percent will be carried by private individuals.

When the various costs are discounted according to time of occurrence and then converted to an annual basis the average annual cost to the Federal Government is $1,064,500, to State and local government it is $47,100, and to private individuals it is $2,453,800. This makes a total annual cost of approximately $3,565,400.

Annual benefits amount to $2.28 per $1 of cost for the entire watershed. Flood and sediment reduction benefits amount to $1.57 per $1 of annual Federal costs. Private on-site benefits amount to $2.24

for each $1 of private cost.

In consideration of the favorable ratio of benefit to costs, public and private alike, execution of the described remedial program under flood-control legislation is recommended.

CHAPTER I. DESCRIPTION OF THE WATERSHED

The Yazoo River drains most of the northwest quarter of the State of Mississippi. Approximately three-quarters of the watershed is undulating to hilly uplands dissected by numerous and comparatively broad valleys. The uplands drain into the western part of the watershed, an almost level, alluvial plain of the Mississippi River known locally as the Yazoo delta. Various tributary streams converge in the delta into the Yazoo River, which enters the Mississippi River at Vicksburg.

The portion of this watershed above Yazoo City, and particularly the uplands east of the Yazoo delta, is an area of serious land misuse responsible for most of the flood problems. This upland area is less than half forested and sustains an exploitative and dwindling agricultural economy. Although the plan for reducing run-off and preventing erosion applies to upland area, the flood problems and potential benefits applicable to the Yazoo delta have also been appraised.3

Four major streams-the Coldwater, Tallahatchie, Yocona, and Yalobusha Rivers-drain the uplands. Works planned by the United States Engineer Department, consisting of flood-control reservoirs, augmented by such channel improvements and levees as are necessary below the reservoirs, will prevent serious flooding of the Yazoo delta by these streams. Some smaller streams drain into the main rivers below existing or proposed reservoirs and others drain directly into the delta. The main stream systems and flood-control reservoirs divide the watershed into natural drainage units which readily lend themselves to study and analysis of treatment needs (table 1 and fig. 1).

A portion of the upland area, the Little Tallahatchie River above Sardis Dam, has been previously reported upon (H. Doc. 892, 77th Cong., 2d sess.). It embraces an area of 988,800 acres, which is eliminated from consideration in this report. However, data for this watershed are occasionally shown for comparative purposes.

* Because some benefits accrue in the delta, the part of it in the watershed above Yazoo City is carried in tabulations as the delta unit. This excludes the Sunflower, Quiver, and other delta streams entering the Yazoo River below Yazoo City.

The Sardis Reservoir on the Little Tallahatchie River is completed, the Arkabutla Reservoir on the Coldwater River is under construction, and the Enid and New Grenada Reservoirs on the Yocona and Yalobusha Rivers respectively are proposed and their construction is considered a surety.

TABLE 1.-Area of principal Yazoo River drainage units above Yazoo City

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1 Included to give complete area of watershed above Yazoo City. These areas are not discussed, except as noted, in this report.

GENERAL PHYSICAL FEATURES

This area has a mild, humid climate with long growing seasons varying from 200 to 225 days. Extremes in temperature range from slightly below 0° F. to 100° F. Mean monthly temperatures vary from 42° F. in January to 82° F. in July. Precipitation averages about 52 inches annually and is generally distributed favorably for agricultural purposes, although severe summer droughts are not uncommon. Light snowfall and ground freezing are occasional during winter months but their effects on agriculture or flood problems are negligible.

The watershed is made up of the delta area and the uplands. The uplands are divided into 4 physiographic areas which extend north and south and roughly parallel each other. They are, from west to east, the deep loess, the brown loam, the clay hills, and the flatwoods. Over the watershed, elevations vary from 100 feet mean Gulf level at Yazoo City to about 500 feet on the highest hills in the northeast part. The deep loess comprises 44 percent of the upland area. Its soils consist of a mantle of wind-transported silt, varying in thickness from 4 to 40 feet, superimposed over clays, sand, and terrace gravels. Topography varies from rugged hills in the southern part to more rolling lands in the north. The natural topography has been altered considerably in many areas by modern erosion and the land is intri cately configured with gullies that often have cut through the loess and the loose underlying sands. Although somewhat lacking in organic matter, the soils are naturally fertile and produce good crop yields under proper treatment. They lose much of their ability to absorb water when left barren or disturbed by cultivation, and excessive surface run-off results.

The brown loam area comprises 32 percent of the upland and is similar to the deep loess in many respects. Much of this area has a thin layer of loess, varying from several feet in thickness on the western edge to only a few inches on the east. The topography is rolling to hilly with moderately narrow flood plains and elevations varying only 100 to 200 feet from flood plains to ridges. In the south central part of this area there are outcrops of clays and less fertile soils; topography is more rolling. This section is known locally as the Blackjack Hills. Except in the latter area, the natural soil

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is moderately fertile. However, the original fertility of these soils has been largely dissipated through misuse, and erosion has caused destruction and abandonment of extensive areas. The thin layer of loess is quickly lost through sheet and gully erosion, and the underlying sand, which is usually several hundred feet in depth, is flushed in prodigious quantities into drainage systems. Many stream channels in the brown loam are bankfull with sand, and frequently valley bottoms are covered from hill to hill with deposits ranging from a few inches to several feet in depth. This condition is so acute that a number of stream valleys have reverted from cultivation to willow brakes. The brown loam embraces the most severe problems of land use in the watershed.

Approximately 19 percent of the upland area is in the clay hills, an area of low, rugged, wooded hills and soils consisting predominantly of clays with interbedded sands. Stream valleys are narrow at the heads but often form broad flood plains as they converge on main streams. Except for bottom lands and scattered, moderately fertile upland patches, the soils of this area are relatively infertile. Where cultivation has been attempted on the ridges and slopes, it has usually been shortlived and the fields have commonly reverted to forests.

The flatwoods extend into the watershed only in the headwaters of the Yalobusha River and occupy only 5 percent of the uplands. The topography is gently rolling with low relief and broad flat valleys. The soils are principally heavy, impermeable clays; they are only moderately fertile to infertile, but the area is extensively farmed because of favorable topography.

THE LAND-ITS DEVELOPMENT AND CONDITION

The history of the Yazoo watershed is principally one of cotton production. For a time, this type of agriculture brought prosperity to a colonial system of agriculture and the area was widely known for its culture and wealth. As in other sections of the old Cotton Belt, this particular crop has been a prime factor contributing to the economic deterioration of the area. Not only has cotton failed to bring sustained wealth, but it has developed a system of cultivation which has all but exhausted the soil resource, and has imposed a form of economic bondage that impedes the development of a more progressive and diversified agriculture.

White settlers first established residence within the watershed in 1800, and in a short time displaced most of the Choctaw and Chickasaw Indians who were occupying the lands of north Mississippi. About 1825, a permanent white settlement was established at Red Banks, near the northern boundary of the watershed, and by 1836 all the area came under organized county government. In 1834 a Government land office was opened at Pontotoc, and within a few years most of the land passed to private ownership. Settlers and homesteaders acquired most of the land, and land companies the remainder. These early settlers found a region of fertile soils traversed by clear, deep streams and supporting an abundant wildlife in its dense, almost unbroken forests of hardwoods and conifers.

Land was rapidly cleared on the better-drained flood plains and the more level uplands; the pressure for open lands soon led to the clearing of steep slopes and further encroachment into wet lowlands. From the early days of settlement to the middle of the nineteenth century,

a self-sufficing type of agriculture was essential and corn was the most important crop. Cotton was gaining favor, however, and was grown on about one-third the cropland, although small grains and food crops held important places. Cotton soon began to dominate agriculture and by 1930 it occupied half the cultivated acreage. Comparatively recent restrictions imposed by the cotton-reduction program, rather than local wishes, have tended to reduce cotton acreages, although the crop still occupies about one-fourth of all the cropland. The reduction in cotton has been accompanied by an increase in corn acreage rather than more diversified uses, and the continued production of clean-tilled crops on highly erodible soils is further aggravating the flood problems confronting this watershed.

Logging and sawmilling industries began in a small way with the early settlers and have been closely associated with agricultural expansion. However, sawmilling did not play an important part in the economy of the region until the twentieth century. The center of lumbering is now in the southeastern part of the watershed where the last sizable areas of timber are being rapidly liquidated.

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Approximately 91 percent of the watershed is in private ownership, about four-fifths of which is in farms and one-fifth in nonfarm ownership. Public land amounts to about 7 percent of the area and the remaining 2 percent is in roads, towns, and miscellaneous uses (table 2). Most of the nonfarm land is owned by lumber companies or nonresident owners and is located in the forested sections of the Yalobusha and South Bluff units.

The farm land is in units varying in size from 15 to several hundred acres. An average size farm totals approximately 140 acres, of which only 55 are in cropland. As the tenant and share-crop system is customary, each farm on an average supports almost 2 families and hence the cultivated acreage per family averages only about 28 acres. About three-fourths of the farms are owner-operated; but most of them have tenants on the property.

Forty-one percent of the upland area is in forest and 59 percent is in open land uses (table 3). The 2 main crops are corn and cotton, both clean-tilled and produced on 35 and 27 percent of the cropland, respectively. Thirty-eight percent of the cropland is devoted to hay, legumes, truck, or is lying fallow. Over one-fourth of the entire upland area is in pasture or lying idle.

TABLE 2.—Major land ownership by drainage units

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s of the 7 percent public land, 8,940 acres is in the Holly Springs National Forest, 20,482 acres is in the Coffeeville land utilization project, and 195,800 is in the existing or proposed flood-control reservoirs of the U.S. Engineer Department. The disposition or use of the reservoir areas is indefinite and acreage or percentage figures hereafter used refer to the watershed exclusive of the reservoir areas, roads, towns, etc. The watershed area used hereafter is 2,950,900 acres.

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