classified as "beneficial." Those which had seriously deteriorated but were apparently in a static condition, if not actually improving, were classified as "neutral." Where deterioration was active the areas were classified as detrimental."

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HAS DEFORESTATION INCREASED THE SEVERITY OF MISSISSIPPI FLOODS

It has not been possible within the limited time available for this study to determine quantitatively to what extent forest depletion has contributed to the Mississippi floods. It has seemed more important to determine how and to what extent forests may contribute to flood prevention. It is sometimes claimed that there has been no marked change in the Mississippi flood situation due to deforestation or any other cause. This study has not undertaken either to prove or disprove such a theory. It does, however, seem well to call attention to certain facts: (1) By the construction of dams at the outlets of certain lakes, Lake Winnibigashish and others, reservoirs have been established at the headwaters of the Mississippi constituting what is said to be the greatest water-impounding system in the world. (2) There is now under irrigation in the Mississippi Valley, according to the 1920 census, a total of 5,005,577 acres of arid land.

The impounding capacity of the lake reservoirs at the headwaters of the Mississippi is reported to be slightly in excess of 95,000,000,000 cubic feet. A reasonable estimate of the average amount of water used in irrigating arid lands on the Mississippi watershed in 24 inches annually. The total amount of water diverted from stream flow and absorbed by the reported acreage of irrigated land each year is therefore more than 435,000,000,000 cubic feet, or more than four and a half times the total capacity of the great reservoir system in Minnesota. Of course, not all of this water is consumed by evaporation and plant growth. A considerable part eventually reappears in springs elsewhere and returns to stream flow, but such return is a gradual process. These are only two outstanding examples of the control of water in the Mississippi Valley out of hundreds that have taken place during the past 40 years. If, therefore, there has not been a marked change in the flow of the river during this period the only possible explanation seems to be that such works beneficial to the stability of stream flow have been offset by other factors of equal power, but working in a detrimental direction.

STUDY REQUIRED CONSIDERATION OF ALTERNATIVE USES OF FOREST LAND

The study of the protective influence of forests in the Mississippi Valley and of the contribution that effective forest protection, necessary reforestation, and the productive use of land for forest crops, may make to flood control, proved to the men engaged in this work that, broadly speaking, the problem was one of the wise use of land. It was found necessary not only to study the areas which are in forests and to determine whether or not they were doing their share toward water and soil conservation, but in many cases it seemed even

more necessary to study lands which, although not now in forests, should be.

It may as well be stated at this time that undoubtedly the greatest burden of silt and freshet run-off contributed to the Mississippi River comes not from forest land, but from farm lands which are being unwisely used. The reports on the 6 major basins and the individual reports on the 73 drainage units uniformly testify to the general fact. Not only are the silt and run-off greater from the agricultural regions as a whole than from the forest regions-it could hardly be otherwise from a great basin only 20 per cent in area timbered but greater in proportion to area.

Again it should be made clear that it is not the original lumbering operations which have mainly caused soil impoverishment, erosion, and floods, but the repeated fires which have usually followed such operations. Nature is a great physician. If given a reasonable opportunity, she displays marvelous skill and promptness in curing many ailments. The forest on a hillside may be removed by fire or logging operations. The first year following such destruction or utilization the snowfall goes off in a torrential rush, which makes a gully of every road, log slide or wheel track. But in a few years. at the most 5 or 6 in relatively humid regions or 15 or 20 in semiarid regions, if there have not been repeated fires, nature will have stopped destructive erosion. But, unfortunately, the curative process of nature is usually defeated by the destructive process of burning the woods. Erosion may be stopped in a few years, but it takes much longer to rebuild the mat of humus to its maximum storage capacity and restore the diminished springs to their original flow. The odds against nature are usually so great that such results can not be expected without effective fire protection and intelligent forest management.

CLASSIFICATION OF FORESTS

For purposes of this circular, the forest lands of the Mississippi Valley have been divided into three classes based directly on ownership-but ownership largely as influenced by use. The three classes are as follows:

1. Commercial forests privately owned.

2. Farm woodlands and forest lands within regions where agricultural interests are generally dominant.

3. National forests and national parks and the unreserved timbered portions of the public domain.

COMMERCIAL FORESTS

Lands classed as commercial forests, which in some regions are often given the general designation "lumber woods," embrace the major lumber regions of the valley and have in the aggregate a total area of 108,000 square miles, including cut-over and waste lands similar in character and location. They are in private or corporate ownership and are the source of most of the lumber produced in

the valley. Generally speaking, they are of negligible value for farmcrop production chiefly because of soil or topographic features. They are broadly grouped under the following subdivisions:

1. "Lumber woods " of Minnesota and Wisconsin;

2. Hardwood region of Ohio Basin;

3. Bottom-land hardwoods of Mississippi Delta;

4. Southern pine region of Louisiana, Mississippi, and Arkansas, with adjoining upland hardwoods.

Each of the foregoing regions will be discussed separately. One important feature common to all is the fire hazard and the injury which has resulted from the ravages of fire. Each region has its season of fire danger. In each region fire control is a major factor in forest perpetuation. Yet in each region this fact has been given little consideration by the landowner until recently unless merchantable stands of saw timber, improvements, equipment, or saw logs have been threatened.

Section 2 of the Weeks law of March 1, 1911, recognized the importance of forests from a stream-protection standpoint and authorized Federal cooperation with the States in protecting from fire the forested watersheds of navigable streams. This encouraged States and private owners in many regions to undertake systematic fire protection. The Clarke-McNary law broadened the basic act, with the result that the Federal Government is now cooperating in organized fire protection with 20 States lying wholly or partly within the Mississippi Valley.

The Clarke-McNary law was based upon the theory that fair division of the costs of protecting forest lands from destruction was 50-50 as between the private owner and the public; that one-half of the public share should be assumed by the Federal Government and one-half by the local powers, and that the work should be directed by State authority.

Under this law progress is being made in protecting the forests of the Mississippi Valley as well as elsewhere, but not as rapidly as could be wished.

On Figure 7, the area in the Mississippi watershed now covered by cooperative fire protection is shown graphically. By comparing this with Figure 6, showing the areas which are critical from a flood standpoint, it will be seen that the blanket of protection falls far short of covering the areas of fire hazard. However, the trouble lies not so much in the shortness of the protection blanket as in its thinness. The organization is far from being adequate to cope with the danger. This situation is shown in detail by Table 4, which gives for each State the area in the Mississippi drainage requiring forest protection, the estimated cost of adequate protection and the extent to which the Federal Government is meeting its 25 per cent of such 35085-H. Doc. 573, 70-23

estimated cost, also the extent to which the private owners and States are meeting their 75 per cent of the estimated cost of adequate protection.

TABLE 4.-Fire-control cooperation, under section 2 of Clarke-McNary law, with States and private owners in the Mississippi Valley1

1 Total funds available, fiscal year 1928, $645,177; additional sum required to provide adequate protec tion, $1,311,499 a year, of which the United States Government should provide an additional $318,409, and the private owners and States should provide an additional $993,090.

It will be seen from Table 4 that at the present time the protection given the forests of the Mississippi Valley is about one-third adequate. Obviously, we can not expect these forests to give satisfactory protection from erosion to the critical areas and from flood to the lowlands unless the forests themselves are adequately protected. After the study which Congress has already given this part of the forest problem, it does not appear necessary to extend the discussion in this circular further than to say that the reports on each individual drainage unit constituting the great basin of the Mississippi indicate that forest fires everywhere play a large part in forest depletion. Even where the standing timber is not consumed or killed, repeated fires are preventing the accumulation of normal undergrowth, small trees, and depth of humus. Fires are in every region reducing the storage capacity of the privately owned commercial forests; and freshet runoff accompanied by unnecessary erosion results. No matter what other steps are proposed, effective fire control is needed in all the forest regions on the Mississippi watershed. It is the first step in developing the possibilities of forests for flood prevention.

LUMBER WOODS OF MINNESOTA AND OTHER LAKE STATES

The lumber woods of Minnesota and the other Lake States is a region of conifers or mixed conifers and northern hardwoods, such as beech, birch, and maple. Its southern boundary runs from east and west as follows: From Kilburn northwest to Black River Falls, thence to Eau Claire and St. Croix Falls, Wis., or Taylors Falls, Minn., thence west to Rush City, thence to Milaca, thence to Little Falls and Wadena, and thence north to Itasca Lake.

This was the region of the great northern white pine and Norway pine forests on the sandy plains. The swamps contained black spruce, northern white cedar, tamarack, and balsam fir. Only a negligible amount of virgin forest remains. Fortunately the watershed problem in this region is not generally critical. Much of the area has sandy soil which, in this comparatively level country, absorbs precipitation promptly and is not subject to erosion. In addition, swamps and innumerable lakes combine to make the whole region a natural storage reservoir. This has been supplemented by a system of six great reservoirs constructed and operated by the United States Engineer Corps. The total capacity of this system, which embraces Lakes Winnebigoshish, Leech, Pokegama, Pine, Sandy, and Gull, is 95,268,100,000 cubic feet.

Despite the fact that these lands are in an exceedingly unsatisfactory condition from the standpoint of timber production, they are not generally a menace to the watershed. The condition of the soil, the topography, and the numerous lakes which act as storage reservoirs and settling basins all combine to furnish a very regular flow of water unusually free from sediment. This statement can be made for the Mississippi River as a whole as far south as the outlet of Lake Pepin, which acts as its last general settling basin.

One exception is noted at the head of the Wisconsin River, where, owing to the character of topography, nature of soils, and climate, the preservation of forest cover is of public importance. An examination of this general region has been made by the secretary of the National Forest Reservation Commission in furtherance of the Weeks law, and an area of about 250,000 acres of rough land with innumerable lakes has been found to have great possibilities as a protection forest under public ownership or control. About 100,000 acres of the area lie on the Mississippi drainage and could probably be acquired at an average price of about $2.50 per acre. This area appears to be the one portion of the lumber-woods region of the Lake States the control of which for forestry purposes would have any material bearing on the flood situation.

It may and undoubtedly will be necessary to establish other public forests in this part of the Mississppi Valley for fire-control and woodproduction purposes, since a great extent of excellent forest land is needlessly lying waste. This may involve the problem of managing swamp lands for forest and game purposes, or may, for example, provide for the enlargement of the present Minnesota National Forest. Such lands, important as their proper use may be from the