WATER. SLOP AND SWILL 415 



many clams out. The necessary height of this will de- 

 pend upon the size of the spillway and the volume of the 

 water going- into the pond at any time. When figuring 

 on the height, allowance must he made for the embank- 

 ment settling six to ten inches where the Ijank is eight 

 to 12 feet deep. In building up the embankment the 

 earth should Ije put on in uniform layers regularly 

 placed, keeping the bank about level. This will insure 

 more uniform settling or packing of the earth and the 

 dam will not be as apt to leak. While the embankment 

 is new it is easily washed down on the inside of the 

 pond by the \\a\-es. In a few months, half of a good- 

 sized dam has been cut down and washed back into the 

 pond in this way. It is true that this washing down 

 by the waves continues year after year, so the in- 

 side of the dam should be set to Bermuda grass and 

 water sedges and willows at once. But to protect the 

 bank until the willows and grass get a start it should 

 be riprapped with brush or old boards, if possible. The 

 Bermuda grass will make a fine covering for the top and 

 outside of the dam as well, and should be put on when 

 the dam is built. 



"The spillway or overflow should be large enough to 

 insure the water in the time of a freshet being taken care 

 of without going over the top of the dam. Where pos- 

 sible, the spillway should be on the undisturbed soi?, so 

 as to prevent as much as possible, washing out. 

 AMierever placed, it should be well sodded with Bermuda 

 grass or some other plant that will bind the soil and keep 

 it from eroding. WHiere ponds are located below cul- 

 tivated fields, considerable difficulty will be experienced 



