141 
—a difference of 3.6 feet in the summer depth of the lake due to the 
opening of the sanitary canal; and we further find, by comparing these 
lake levels with the areas of the lake at different depths, as shown by the 
second of the tables, that the summer expanse of the lake averaged 1,943 
acres before 1900, and 5,072 acres since 1899—an increase of more than 
two and a half times in the area of this lake, due to the higher levels pro- 
duced by the canal. 
AVERAGE LEVELS oF THOMPSON LAKE, 
JUNE, JuLY, AUGUST, AND SEPTEMBER, 
1874-1907 
Thompson Lake 
Year Memphis datum * Havana gage 
Elevations above 
1874 433.25 1.48 
1875 437.6 5.93 
1876 439.25 7.58 
1877 435.62 4.95 
1878 438 iene 
1879 434.62 3.95 
1880 437.37 6.70 
1881 436.12 5.45 
1882 440.75 9.08 
1883 436.7 5.03 
1884 436.7 5.03 
1885 437.5 5.88 
1886 . 435.87 4.20 
1887 433.75 2.08 
1888 437.87 6.20 
1889 438 6.33 
1890 437.75 6.08 
1891 437 Hass 
1892 441.5 9.83 
1893 435.75 4.08 
1894 435.25 3.58 
1895 434 2.33 
1896 436.62 4.95 
1897 435.75 3.08 
1898 437 5.33 
1899 436.25 4.58 
1900 438.12 6.45 
1901 436.87 5.20 
1902 444.87 13.20 
1903 440.87 9.20 
1904 439.75 8.08 
1905 440.75 9.08 
1906 438.25 6.58 
1907 443 .62 1195 
Average, 1874-99 436.76 5.09 
Average, 1900-07 440.36 8.69 
*“\emphis datum” is 7.3 feet below sea-level. 
