KEOKUK DAM 
127 
received was that “hackleback” (sturgeon), spoonbill cat (paddlefish), and suckers 
were disappearing, but that carp, buffalo fishes, bass, sunfish, and crappie had greatly 
increased. There was a marked difference of opinion in regard to catfish, and one 
dealer stated that catfish, while fewer, were larger. It was also said that whereas 
there were three commercial fishermen at Dallas City in 1917 there were 35 in 1920. 
More definite information in regard to the commercial fishery is found in the following 
section, and the individual species of fish are treated in a later paper. (Coker, 1930.) 
SUMMARY OF OBSERVATIONS 
Keokuk Lake, formed by the dam at Keokuk, Iowa, extends 42 miles to Bur- 
lington, Iowa. The width varies from about l / 2 to miles or more, and the total 
area is about 60 square miles. The greatest depth is about 36 feet. The increase 
in volume will ultimately be about 14,000,000,000 cubic feet, less the reduction due 
to filling in by sediment and to reclamation by levees and drainage. The stage, and 
therefore the area, presumably fluctuates substantially less than that of the river 
before the construction of the dam. The turbidity and temperature probably are 
not greatly different from what they were under former conditions, but the velocity 
of the current has been reduced, the reduction near the dam being very great. The 
old rock bottom has been covered deeply with silt. The lake, while supporting few 
rooted aquatic plants, up to 1916 gave evidence of an enriched fish-food content, 
and there were reasons for expecting that this condition would continue to improve. 
Land submerged by the widening of the water area should supply favorable spawning 
beds for game and food fish, but a very large portion of the most favorable areas has 
been reclaimed for agricultural uses by the construction of levees and by drainage. 
DEDUCTIONS FROM THE COMMERCIAL FISHERIES OF LAKE KEOKUK 
AND LAKE PEPIN 
One of the most practical means of determining the effect of the dam upon the 
fishes of the river would be the comparison of the conditions of the commercial 
fisheries before and after the construction of the dam. Unfortunately, we have no 
comparable surveys of the fisheries of the river for such times. This lack has been 
partly compensated for by surveys of two of the most important regions of fishery 
above the dam, made soon after the construction of the dam and after periods of 3, 8, 
and 13 years, respectively. Since the report was first submitted for publication 
another survey (for 1927) has been completed, and we are enabled to include 
comments based upon statistical data in manuscript offered by the division of fishery 
industries. We have not reorganized the section, but we have added a column to 
each of Tables 6 and 7 and have inserted references to the results of the survey for 
1927 wherever pertinent. 
It is evident that the dam could not have exerted its full effect upon the fish life 
of the upper river within a year and that whatever effect may have followed a year 
after the obstruction was completed should have been more conspicuous in subse- 
quent years. Accordingly, a comparison of the fisheries in Lake Keokuk for 1914, 
1917, and 1922 (the dam having been completed in 1913) should give a fair indi- 
cation of what was happening in that part of the river most immediately affected 
by the dam. Furthermore, if the dam was far-reaching in its effect by shutting 
off migratory fishes from the upper river, then a comparison of the fisheries in Lake 
Pepin, 400 miles (by river) to the north, for the same years should give some indi- 
