114 
BULLETIN OF THE BUREAU OF FISHERIES 
in Table 3. Although there are differences each year, the records prior to 1913 cover 
approximately the months of March to December, inclusive, but all observations 
given for those years are included in the computations. The stages of 1914 and 
subsequent years are recorded complete, but the computations are based on records 
from March to December, inclusive. 
Table 4. — Oscillations of river stage, in feet, at Keokuk, Iowa, 1910—1912 and 1914—1919 ( including , 
for comparison, yearly fluctuation at Davenport, Ioiva ) 
Year 
Daven- 
port, 
Iowa 
Keokuk, Iowa 
Differ- 
ence 
between 
highest 
and 
lowest 
in year 
Differ- 
ence 
between 
highest 
and 
lowest 
in year 
Difference between first of 
month and first of month 
following, maximum and 
minimum 
Difference between Sunday 
and following Sunday, 
maximum and minimum 
Difference between morning 
and following morning, 
maximum and minimum 
Least 
Most 
Average 
Least 
Most 
Average 
Least 
Most 
Average 
1910 
7.8 
12.0 
0.9 
8.4 
2.86 
2.9 
0.63 
3.0 
0. 16 
1911 . 
10.6 
12.3 
1.8 
11.8 
4.76 
10.4 
1.33 
2.9 
.29 
1912 
11.3 
17.7 
. 1 
5.8 
i 1.7 
5.6 
1.31 
6.4 
.31 
Average.. 
9.9 
14 
1. 33 
10.23 
3. 98 
6. 30 
1.07 
4.1 
.25 
1914 
8.9 
13.3 
1.4 
7 
3. 97 
5.8 
1. 10 
3.6 
.33 
1915 __ 
8. 1 
15 
2.7 
10.2 
6. 19 
5. 2 
1.81 
5.2 
.43 
1916 
13.9 
17.6 
.2 
8.6 
2.75 
9 
1. 30 
4. 87 
.37 
Average.. 
10.3 
15.3 
1. 43 
8.6 
4.3 
6.67 
1. 40 
4. 56 
.377 
1917 
11. 1 
16.6 
. 1 
12. 8 
2.66 
0.5 
5.9 
1. 36 
6.5 
.33 
1918 
9. 3 
16.6 
.3 
7.2 
3. 32 
4. 5 
1. 01 
2.8 
.36 
1919 
13.3 
18. 1 
.4 
8.7 
3. 15 
.3 
8.7 
1. 95 
4 
.43 
Average.. 
11.2 
17.1 
.27 
9.57 
3.04 
.27 
6. 37 
1. 44 
4.43 
.373 
1 9 months. 
It will be observed that the average annual fluctuation of river stage at Keokuk 
was more marked during the 3-year period (1914-1916) immediately following 
the construction of the dam (15.3 feet) than during the 3-year period (1910-1912) 
preceding its construction (14 feet), and even more so during a following 3-year 
period (191 7-1919) — 17.1 feet. It was urged by the power company that the differences 
indicated by these figures were due to climatic causes rather than the dam. They 
claimed that the daily combined flow of water through the power house and over the 
dam was equal to the natural flow that would occur here, except that they occasionally 
raised or lowered the lake very gradually and except that the wind made a slight differ- 
ence. According to their computations the variation resulting from the raising or 
lowering of the lake amounted to only two or three-tenths of a foot a day. 9 Whether 
or not tills would make enough difference to account for the instability shown by the 
foregoing table may be doubted. 
Certainly, some corroboration of the view of the power company is derivable 
from a comparison of the fluctuations of stage at Davenport, Iowa, during corre- 
sponding periods. Davenport is far enough above the dam (120 miles by river) to 
be beyond the possibility of effect from the dam. Nevertheless, the fluctuations dur- 
ing corresponding 3-year periods have displayed a somewhat similar history. The 
average yearly range for the period 1910-1912 was 9.9; for the period 1914-1916 it 
was 10.3; and for the period 1917 to 1919 it was 11.2. The years of greatest fluc- 
tuation were the same as for Keokuk, namely, 1912, 1916, and 1919. Evidently, 
5 Based upon verbal statements of an officer of the company to Emerson Stringham in 1918. 
