THK AXULKM AND HrXTS.MAX 99 



region where muskrats occur it is advisable to place wire 

 screening in the embankment, extending it about 1 foot 

 above and 2 feet below the water level, and burying it in a 

 bank to a depth of 6 inches. For this purpose extra-heavy 

 poultry wire or close mesh stock-fence wire will answer. Ex- 

 cavating is not to be recommended if the earth required for 

 the embankment can be otherwise obtained. 



"The inside slope of an earth embankment should be 

 approximately 18 inches horizontal to 1 foot vertical, the 

 exact proportion varying somewhat with the nature of the 

 soil. The outside slopes may be 1 to 1, and after settling, 

 they should be sodded. The thickness of an embankment 

 at the water level should never be less than the depth of 

 the water. For small ponds the top should be at least 3 

 feet across, and not less than 6 feet where the pond is large 

 enough to admit of considerable wave action. No under- 

 brush, logs, or other materials subject to decay should en- 

 ter into an embankment, but imperishable substances, such 

 as rocks, may be used. The filling should not be undertak- 

 en in sections, but should progress by layers over the full 

 width of the embankment. If acquatic vegetation cannot 

 be obtained for planting near the water edge, that portion 

 may be rip-rapped with rocks to prevent washing by waves. 



"The depth of the pond must depend on the climate. 

 In regions where little or no frost is encountered, a water 

 depth of 5 feet is sufficient, but in northern latitudes it 

 should be from 10 to 12 feet. The outlet may be of lumber 

 or of cement. 



"If spring water is the main source of supply, it may 

 freeze sufficiently to harm the fish. Under this condition 

 ithe deepest part of the pond need not be more than 5 feet. 

 If the pond has a good supply of water, no harm will re- 

 sult from surface freezing so long as the outlet is kept 

 open. The extreme depths given are for such ponds as 

 have a very limited supply and are apt to freeze to a con- 

 siderable depth. 



