THE GERMAN CARP IN THE UNITED STATES. 627 
little avail, since the places were so large and the conditions so varied 
that it was practically impossible to get the fish out. 
There remain still to be considered those ponds in which the water 
can be maintained at a definite height irrespective of the varying level 
of the neighboring waters. Under suitable conditions they could 
probably be constructed best in valleys and natural depressions 
according to the plans already outlined as being in general use in 
carp-cultural establishments. Under the conditions of our fisheries, 
however, it is a matter of great economic importance that these ponds 
should be as near to the fishing grounds as possible, and as the land 
there is low and marshy the ponds must for convenience be constructed 
in or along these marshes. For this reason the problems presented 
are very different from those met with in the building of ponds on 
higher ground. The greatest difficulty comes, of course, in the mat- 
ter of the drainage of the pond, since its deepest portions of necessity 
lie below the level of the outside waters. An idea of the methods - 
that have been devised can probably best be conveyed by giving brief < | 
descriptions of two or three ponds which have now been in use for ~ 
several years. 
Along the marshy shore of the Portage River, a mile or two above 
Port Clinton, Ohio, is a successful carp pond covering some 30 to 35 
acres, and owned and managed by two brothers, who also conduct at 
the same time a fruit farm immediately adjacent to the pond. The 
site of the pond was originally a marsh, flooded by backwater from 
the river, where the carp commonly came in to feed and to spawn. It 
was first converted into a pond (see diagram, p. 628) by throwing up 
an embankment along the river side, cutting it off from the river, 
but still leaving it connected by an open gateway protected by a screen 
or grating. The inclosed water was at the same level as the outside 
water, and as the level rose and fell a stream rushed in and out through 
the gateway. This plan was found to be unsatisfactory, as the 
impounded fish crowded about the grating, neglecting to feed, and at 
the same time becoming badly bruised by their contact with the bars. 
The embankment was then raised and the gateway closed, so that the 
water in the pond could be maintained at a level 1 to 2 or 3 feet or 
so higher than the mean level of the river, while at the same time the 
increased height of the water caused it to spread farther back over 
the land, enlarging the pond, and encroaching upon a neighboring 
cornfield, a large portion of which was thus converted into marsh. 
The principal embankment was easily raised by having a shovel-dredge 
make a cut along the inner side, the excavated mud being deposited on 
the outer side of the cut to form the embankment. The lower por- 
tions were built with a scraper at a time when the river was especially 
low, at which periods the pond can be practically drained of water. 
During rainy seasons springs kept the water well up to the desired 
EY 
