FISH PONDS ON FARMS, 13 
excavated, and the water level therein will be higher than the sur- 
rounding land. 
The method of constructing pond embankments is governed by 
the topography of the land, the character of the soil, and the volume 
and pressure of the water to be confined. All made embankments 
should be at least 6 feet wide at the top, and the sides sloped not less 
than 2 feet to each foot in height. For instance, a 6-foot fill should 
be 30 feet wide at the base and 6 feet at the top. 
Prepare the foundation by plowing the site of the embankment, 
after first removing all trees, underbrush, rock and sod, and, as an 
extra precaution against seepage, dig a trench 12 inches deep along 
the median line. This will form a break, or set-off, between the 
original ground and the made construction, which is a point of natu- 
ral weakness. The filling should progress by layers over the full 
width and length of the levee as a continuous operation rather than 
_ by sections; otherwise the completed work will later develop checks 
by reason of variations in material and compactness. Rocks are of 
use as a protecting riprap on the slopes after completion. 
In case the water supply to a pond is taken from a creek, the latter 
must be dammed and an intake built above the construction provided 
with screen and dam boards, from which a water conduit must be laid 
to the pond. The dam should be provided with an ample spillway, 
which may best be constructed of concrete. 
The shape or outline of the pond is immaterial. Currents of 
water are undesirable in the propagation of the spiny-rayed fishes. 
In fact, the best brood and rearing ponds are those which are sup- 
plied by backwater from other bodies, and if there is reasonable 
depth and a fair growth of vegetation no stagnation will result. 
Success in pond fish culture is being attained with widely varying 
forms of construction. To a considerable extent fish will adapt 
themselves to existing physical conditions. In nature they seek 
comparatively shoal waters in which to spawn, by reason of the 
prevailing higher temperatures, and during certain stages of their 
growth the young choose similar depths, where food is plentiful and 
beyond the bounds of the customary range of large fish. Relatively 
deep waters must be accessible to the stock fish during winter months, 
and what this depth shall be will depend largely upon the latitude 
of the location; cold climates where great thickness of ice forms re- 
quire the deepest pools. 
Experience teaches that breeding ponds should be excavated to 
hold not less than 12 inches of water at or near the margins; that 
one-fourth of the pond area should range from 12 to 80 inches in 
depth; and that one-half its total area should be not over 3 feet 
deep, the bottom of the remainder to slope from this depth to 6 fect 
or more at the outlet. Avoid abrupt slopes. Provide complete drain- 
