70 FOREST LANDS FOR THE PROTECTION OF WATERSHEDS. 



far exceeded in magnitude and destructiveness that which actually took place. 

 Wherever forests existed in the higher altitudes they did have this effect. 



Having now considered the influence of forests upon stream flow from a 

 theoretical standpoint, let the records themselves be examined as far as they 

 are available. These records in the United States, unfortunately, are not so 

 useful as might be wished, because of their brevity. No continuous records on 

 any of our streams run back for more than eighty years, and most of them less 

 than half as far. This is far short of the two hundred years considered by 

 certain European engineers who investigated Wex's theories as the minimum 

 period " necessary in order to draw a reliable conclusion " upon this subject. It 

 does indeed seem absurd to take present-day records, as is constantly done, and 

 draw conclusions one way or the other as to comparisons with the past, of 

 which records are entirely wanting ; but such as they are, a few of these records 

 are given in Table J. They include in most cases both high and low water, 

 although the low-water records can not, in the nature of the case, be of very 

 much value. Works of channel improvement on most of the streams have prob- 

 ably affected somewhat the low-water stages for the same dischai-ge, while, as 

 is well known, a given stage, even in a natural stream, does not mean the same 

 discharge at different times. 6 It is really the discharge of the streams rather 

 than the stage that forms the correct basis for comparison : but data for dis- 

 charge are almost wholly wanting. 



An examination of these records shows how utterly impossible it is to find 

 anything in them to support the current theory of forest influence. They prove 

 conclusively that there has been no marked change since the settlement of the 

 country began, and that such change as there has been is on the side of higher 

 high waters and lower low waters before the forests were cut off. What the 

 record would be if we could go back two hundred years can not be said, but it 

 may safely be conjectured that it would show both floods and low waters that 

 would equal or surpass any modern record. It is the experience of every engi- 

 neer who has the opportunity to observe the action and study the history of 

 great rivers to find everywhere evidence of the occurrence of higher waters than 

 any of which he has positive record. The upbuilding of bottom lands, the sur- 

 vival of old water marks, and many other indications show that, great as are 

 modern floods, those of the past were greater still. In the very nature of the 

 case, it is not possible to find similar evidence of former low waters, because 

 such evidence is wiped out by every succeeding high water; but whoever will 

 take the trouble to study records of early expeditions on our rivers, when barges, 

 keel boats, and similar craft were used, will conclude that extreme low water 

 is not a modern development by any means. Measurements of the Monongahela 

 River, at Brownsville, in 1838 and 1856, low-water years, gave discharges of 75 

 and 23 cubic feet per second, respectively. It is quite certain that the river has 

 uot fallen so low in late years. At Pittsburg in 1S95 (the driest sesisou in 

 recent years) it fell to 160 feet. 



In the Weather Bureau report, Montana section for June, 1908, it is stated 

 that " the rainfall was phenomenally heavy over most of this district, and, com- 

 bined with the water from the rapidly melting snow in the high mountains, 

 caused unprecedented floods in nearly all streams." 



6 During the past twenty years the low-water stage of the Mississippi at St. 

 Paul has been materially modified by reservoir action. 



