. The Farm Fishpond 201 i 



in large quantities, actually poison or asphyxiate fishes. Fortunately water 

 containing the last two gases may be purified by passing it over a series 

 of falls, during which process the gases are replaced by oxygen from the 

 air. In general, the water from springs originating in limestone regions 

 contains much carbon dioxide and should be tested before using. Spring 

 water containing ver}^ much hydrogen sulfide should not be used, but, 

 if there is only a slight odor or taste of this gas, it may be eliminated as 

 in the case of marsh gas and carbon dioxide. 



A spring should be protected from contamination by surface water and 

 drainage from stables and like places. It is well to dig a basin in the 

 spring itself and to line this with a wall of concrete, loose brick, or stone, 

 which should extend from eight to twelve inches above the surface of the 

 ground. A ridge of clay soil thrown up around this wall will effectively 

 turn away all surface water. 



Should it become necessar\^ to build a pond at a higher level than the 

 spring, a hj^draulic ram may sometimes be used. It must be understood, 

 however,, that only a small part of the water suppl3% one-seventh or less, 

 can be forced to a higher level; and that for every rise of ten feet from 

 ram to pond, there must be at least one foot fall from spring to ram. The 

 greater part of the water is wasted by this method; hence it is applicable 

 only to a spring of large capacity. 



Creek water 



A creek not immediately fed by springs, as a rule, drains a rather large 

 area of land; therefore it is subject to great changes in volume, turbidity, 

 and temperature. A pond directly connected with such a creek is like- 

 wise subject to the same changes. The temperature is beyond control. 

 The turbidity cannot be regulated without the expenditure of a large 

 sum of money. It is therefore fortunate that these two factors merely 

 inconvenience pond management and do not in themselves seriously 

 affect the healthfulness of the inhabitants of the pond. The volume of 

 water, however, flowing into the pond must be kept within certain limits 

 throughout the year, and to this end special structures are necessary. 

 It is customary to build a low dam across the creek bed, and on one side 

 of the bank of the pond so formed to construct an intake box, from which 

 the desired amount of water can be taken. In locating the dam, two 

 things must be kept in mind : first, the fishpond should be fed by gravity 

 flow; second, the water must not be dammed back on to another man's 

 property without his written consent. Thus the dam should be far 

 enough up stream to feed the pond properly and yet not too near another 

 person's property. A drop of at least two feet from the line fence to 

 the water level in the dam should be allowed. 



