At the beginning of the investigations the matter was treated as of local concern only, but as the work progressed the broad aspect of the problem and its national scope were realized, as it became evident that Pittsburgh's floods had a direct bearing upon the flood troubles of other communities. Further study disclosed the fact that inseparable from the flood problem was the question of navigation, sanitation, water supply and water power, and that the valleys of the Allegheny, Monongahela and Ohio Rivers could be benefited wherever conditions are favorable for the construction of storage reservoirs. On many of the principal tributaries of the Ohio below Pittsburgh, the topography is favorable for storage reservoirs upon a large scale, and floods could be prevented throughout the Ohio valley by extending the plans of the Flood Commission.

An exhaustive report, consisting mostly of original data, has been published by the Commission, as the result of nearly four years of painstaking work. It is said that this report forms the most comprehensive treatment of a subject of this kind that has ever been carried out. The report contains over 900 pages, including numerous maps and diagrams, and a large number of illustrations, showing flood damage, reservoir sites, forest conditions, etc.

FLOOD DAMAGE.

Pittsburgh, which has a population of 533,905, and about twice as much with the contemplated greater city, is located at the head of the Ohio River and at the confluence of the Allegheny and Monongahela Rivers. The combined drainage area, above the city, amounts to 18,920 square miles. Of the two rivers, 150 miles, directly connecting with the city, have been slackwatered. About 14,000 miles of navigable waterway lies below the city. The National Government, in a few years' time, will have the entire 967 miles of the Ohio River improved.

The tonnage of Pittsburgh, incoming and outgoing, amounted in 1910. to 167,000,000 tons, of which 11,000,000 tons consisted of river traffic. The above total tonnage, which has doubled in the last six years, is twice as great as the combined tonnage of New York, London, Hamburg and Marseilles.

As is frequently the case in communities situated upon the inland rivers of this country, the most important commercial and industrial parts of Pittsburgh are located upon the low lying areas bordering the water. The need of free access to water and of rail and water transportation naturally brings about such development. In fact, on account of the topography, rail communication can in many cases be satisfactorily established only along the stream. Such a condition, however, frequently causes great suffering and interruption to business, involving not only the districts in direct touch with the river, but the whole community.

During the progress of the investigations, it became evident that unless some adequate method of flood relief could be devised and carried out, the larger portion of the flood affected areas could never be properly developed, and the capital invested therein would continue to suffer. The general needs of building operations and of city improvements will of necessity keep pace with the advance of population; and the flood damages, which in their effect involve the home conditions and business life of the entire city and surrounding communities, will become correspondingly greater.

In ascertaining the extent of flood damage to the city, a careful investigation was made of three floods which occurred within a period of about twelve months, from March 15, 1907, to March 20, 1908. In the conduct of this work it was noted that while those coming in direct contact with the floods are alert to the seriousness of the situation during the flood, the matter is, however, after a time almost forgotten; the disposition in most cases apparently being to take the troubles as they come rather than to do anything in the way of even attempting to devise means of relief.

The classification under which this work was done, and the monetary amount of direct losses within the city by the three floods may be given as follows:

Damage to buildings, equipment and machinery.

Damage to materials.....

Loss to employer by suspension of business..

Loss to employee due to shut-down....

Expense of cleaning up....

Charities dispensed and funds for prevention of disease..

Fires uncontrolled through inaccessibility or lack of water pressure..

Total

$782.400

1.698.000

1,974,200

1.308,300

547,400

27,800

175,000

$6,514,000

It was found that the loss ranges as follows: For the flood of 27.3 feet, $414,700; 30.7 feet, $839,800; 35.5 feet, $5,259,500.

The area comprising the larger part of the mercantile, industrial and railroad interests amounts to about 3,000 acres, 1,540 of which was covered by water during the great flood of 1907, which had a height of 35.5 feet, or 13.5 feet above the danger line. This flood remained sixty-five hours above the danger line of 22 feet. About fifteen miles of river front land are occupied with industrial works of various kinds. The assessed value of real estate as affected by the 1907 flood amounts to about $160,000,000, and a careful estimate shows that this property is nearly $50,000,000 lower in value than it would be if protected from floods. Using the results obtained for the above floods and the flood records for the past twenty years it is estimated that the direct loss to the city has amounted in that period to about $17,000,000, over $12,000,000 of which occurred in the ten years preceding January, 1911.

Based on the assumption that in the next two ten-year periods there will be no increase in number or height of floods over those occurring in the ten years just preceding January, 1911, it is estimated, if protective measures are not provided, that the flood losses at Pittsburgh in the next twenty years will amount to about $25,000,000. As records show, however, that floods are increasing in frequency and height, it is estimated that the losses in the next twenty years will amount to about $40,000,000, or nearly twice as much as it will cost to carry out the flood prevention measures recommended by the Commission.

The Commission did not have resources for securing the amount of damage at the many important points along the rivers, above and below Pittsburgh, but at Wheeling, W. Va., it was ascertained, for instance, that about $1,000,000 was lost during the flood of 1907. Authorities consider that the total loss along the Ohio Valley for the two floods of 1907 amounted to more than $100,000,000. This is indicative of the vast losses occurring annually all over the country.

In addition to many miles of street car tracks, streets and alleys, about 435 acres of railroad and industrial yards were covered, in addition to 17 miles of main railroad, by the big flood of 1907.

At high stages many manufacturing plants must close down. The following is quoted from a report of the American Iron and Steel Association: "Damage to the iron and steel industry unprecedented. At beginning of March, 1907, flood there were forty-four blast furnaces in Allegheny County in blast, and of these thirty-eight had to be banked for an average of two days. Work at most of the sixty-five or seventy rolling mills and steel works was suspended." Many of the open-hearth furnaces were badly damaged and some of them practically ruined.

FLOOD PROTECTION.

Regarding methods of local treatment, studies and estimates of cost. were made of the following: A wall of about twenty-five miles in length to be built in the city along the river fronts; also for deeping, widening and straightening of the river channel by dredging.

The wall, high in places above the river streets, would prevent overflow by confining the floods to the channel. Dredging and removal of obstacles in the channel, bank encroachments, etc., as can now be accomplished, would have comparatively slight effect in reducing flood heights. and these means were, therefore, not broadly recommended. Furthermore, these forms of treatment would be of local flood benefit only and communities above and below Pittsburgh would continue to suffer in various ways.

A wall of limited height, however, is really desirable, at least along certain parts of the river. While reservoir control would result in reclaiming considerable areas of land, a wall would provide means for

adding to the amount and greatly improve the appearance and usefulness of the banks. The handling of cargoes to and from river boats would be greatly facilitated by means of modern devices. Sheds could be constructed along the wall and close to the boats which would lie alongside. Such arrangement would make feasible the bringing directly of river and rail transportation with the great advantage of through rates and routes, a condition which is now lacking at practically all points on American rivers.

FLOOD PREVENTION.

In the treatment of the flood problem, prevention, by the use of storage reservoirs, for the purpose of holding back the damaging part of the flood water, is the rational and comprehensive method, as it goes to the source of the trouble, and extends its benefits throughout the entire river valleys, not only in the form of flood relief, but by improvement of the low-water flow, due to the release of the impounded flood waters during the dry season.

Forest cover is beneficial to some extent in retarding the run-off and in improvement of low-water flow, and the attitude of the Flood Commission is to support such National and State legislation as will tend to preserve and increase the present forest cover. The Commission, however, recommends the use of the storage reservoir system, supplemented by other means where necessary, for the reason that such a system could be speedily brought about. The use of storage reservoirs for flood control is not a new idea in this country and this method is now successfully empolyed in European countries.

The exhaustive surveys and studies for flood prevention disclosed the fact that forty-three reservoir sites are available in the Allegheny and Monongahela drainage basins above Pittsburgh, and that while not needed for present purposes additional sites are feasible. The fortythree projects would have a total capacity of 80,500,000,000 cubic feet, would cost $34,000,000, and would control about sixty-two per cent. of the total drainage area above the city. After a careful analysis it was found that a less number of reservoirs was practically as effective, under proper manipulation, and a selection was made of the most favorable ones, seventeen in number. These would have a total capacity of 59,500,000,000 cubic feet, would cost $21,700,000, or about $364 per million cubic feet of storage capacity, and would control fifty-four per cent. of the total drainage area.

As a basis, eleven of the principal floods, occurring within recent years, were exhaustively studied and it was found that the seventeen selected reservoir projects would reduce all of them, with one exception, to below danger line. Investigation showed that a low wall built at comparatively small cost along a few parts of the low-lying river fronts.

could be used in combination with the seventeen reservoirs to prevent overflow by the highest known floods. This combination was therefore recommended, the total cost being estimated at $22,350,000.

Some of the benefits to be derived by preventitive methods and stream regulation and development, may be summarized as follows:

1. Reducing or doing away with floods and flood damages and their constant menace, thereby encouraging and making possible for present and future generations full development of affected

areas.

2. (a) Improving of navigation, by permanently increased stream flow in slackwatered rivers, where dry weather flow is frequently inadequate to furnish desired draft, thus providing uninterrupted transportation not only for present business but for future demands. (If the reservoirs were brought up to maximum capacity, that is, above flood control requirements, the low-water flow of the Ohio, at Wheeling, ninety miles below Pittsburgh, would be nearly six times the present minimum, giving an increase in stage of 3.7 feet. One of the largest floods would have been reduced over thirteen feet.)

(b) Making possible slack water on certain rivers, worthy of attention, but now unimproved largely on account of absolute lack of sufficient water.

(e) Reducing velocity of current, due to lowering of high stages, thereby making safer the maneuvering of river craft; reducing wide fluctuations in water levels, particularly at river ports, facilitating thereby the handling of cargoes and increasing clearance under bridges. (Under a certain bridge at Pittsburgh, investigations show that during the past fifty-three years there has been an average of fifty-seven days when the ordinary steamboat could not pass. Had the proposed system of reservoirs been in operation the water would have been lowered so that there would have been an average of only three days.)

(d) By having the great fluctuations reduced, the erosion of the banks along the bottom lands and at other places would naturally be considerably lessened.

3. Improving sanitary conditions and increasing the quality and quantity of the supply for municipal and industrial purposes. High stages leave deposits on banks, becoming a nuisance to health; and low stages are frequently unable to properly carry away polluted water stagnating in slack water or natural pools.

4. Developing water power, which is feasible under favorable conditions in connection with reservoir systems for flood prevention.