SPOLIATION OF THE FALLS OF NIAGARA 293 



the outlet of Lake Huron had also been lowered. This was the starting- 

 point of the investigation into the spoliation of Niagara. The channel 

 of the river had been deepened just after 1890, owing to natural scour 

 by the currents, the effectiveness of which was increased by the powerful 

 jamming of vast quantities of ice against the barriers at the Upper 

 Eapids, immediately above the falls, and to a small extent by the 

 shifting of the boulders on the river bed just below the outlet of Lake 

 Erie. 



8. Corrections of Discharge Measurements. — The discharge meas- 

 urements had been made by the U. S. Lake Survey after the lowering 

 of the lake outlets had occurred, that of the Erie outlet causing the 

 subsidence of the lake level to nearly one foot. As the daily records of 

 the lake fluctuations have been kept for fifty years or more, it was 

 possible to determine the discharges of the rivers throughout that time. 

 Failing to take into consideration this lowering of the lake outlets, 

 the calculations of the river discharges prior to 1891 were excessive, and 

 those of Lakes Huron and Erie showed inadmissible differences; as also 

 found by Mr. Kussel. These discoveries reduce the calculated dis- 

 charge of Niagara Eiver, prior to 1891, by 22,000 cubic feet per second, 

 which would bring its volume from 1860 to 1890 into agreement with 

 the mean measured discharge for the fifteen years from 1891 to 1905, 

 inclusive, or 204,000 cubic feet per second; and the low water discharge 

 has fallen to 160,000 cubic feet. There have been years of high water 

 and others of low, yet by taking groups of years, the mean values are 

 remarkably uniform, but the latter period must not be regarded as one 

 of low water, a fact which I can not too strongly emphasize, although 

 the lake levels have actually been much lower than during the preceding 

 period, due, as just stated,- to the lowering of the outlets. Such years, 

 however, as 1901, showed very low water in Lake Erie, and reduced 

 discharge of Niagara Eiver. 



9. Present very High Water. — In contrast with this, the lake-levels 

 during 1907 were extraordinarily high, increasing even till the present 

 month (June, 1908). Fragmentary information, preserved, indicates 

 that Lakes Erie and Ontario were unusually Ioav in 1819. The fuller 

 record of subsequent years shows that the highest water occurred in 

 1838, and nothing has been comparable to it until the present high 

 stages. Although these do not make the lakes appear to be now so 

 high as seventy years ago, this is because of the lowering of their 

 outlets and the further diversion of water for power purposes, both of 

 which, if allowed for, would bring the lakes to higher levels than at any 

 time since records have been kept. The 1838 period of high water 

 began in that year and continued until 1840, after which the lake levels 

 subsided to normal conditions. There is no reason to suppose that 

 the present extreme high-water conditions will continue longer than 



