36 FISH FARMING I 



on the side of the gorge down which the stream flowed. Into 

 this channel the stream is diverted from the top end of the 

 gorge while the dams are being constructed, and communicat- 

 ing channels are cut, as a.t H, as the work advances. The mate- 

 rials obtained in cutting these channels are utilised in the 

 construction of the dam, and the channels now are used to 

 carry off surplus and flood water. At M is a sluice to control 

 the passage of water from the pond into the channel H ; the 

 redds are at G G G ; and F is the stream below. Now, in this 



A LAKE IN THE HILLS. 



caise the fall is so great that the bottom of the pond A at its 

 deepest part is above the level of the stream F below ; and it 

 is the same case with the remainder of the series of lakes. To 

 empty it or to adjust the Water in it to any height, therefore, 

 simply means the placing of a controlling sluice at D, connected 

 with a drain (shown by the dotted lines at E). passing through 

 the bottom level of the dam and discharging its contents into 

 the stream F below. The controlling sluice D and the sluice M 

 are really all that is necessary to control the lake; but, to 

 make assurance doubly sure, a horizontal box screen is fixed 



