THE GAME BREEDER 



157 



Then drop a float in the water and note 

 the number of seconds it takes to traverse 

 the given distance. The product obtained 

 by multiplying the average width in 

 feet by the average depth in feet by the 

 velocity (expressed in number of feet 

 per second) will give the flow of the 

 stream in cubic feet per second. From 

 the figures so obtained ii is advisable to 

 deduct about 20 per cent., as , the sur- 

 face velocity of water is in excess of the 

 actual average velocity. 



High temperatures in season are nec- 

 essary in brood and rearing ponds. If 

 the water is cold at the source, the fault 

 must be corrected by reducing the inflow 

 to the lowest quantity that will maintain 

 a uniform level, thus allowing the max- 

 imum absorption of warmth from the 

 sun and air. Water that does not fall 

 below 60 degrees F. in the brood pond 

 during the spawning season is desirable. 



Sources of Water Supply for Ponds. 



Springs are the most dependable of 

 all sources of water supply, requiring 

 the minimum expenditure in preparation 

 and being the least subject to outside 

 influence. The presence of injurious 

 mineral substances can usually be de- 

 tected without expert analysis, but the 

 amateur fish-culturist may be surprised 

 to learn that so-called pure water often 

 carries abnormal proportions of oxygen 

 or nitrogen gases in quantities inimical 

 to fish life. This may be due either to 

 subaeration or superaeration, and the re- 

 sults following the use of such water 

 will be as disastrous in the one case as 

 in the other. 



This contingency and the requisite of 

 high temperature make precarious the 

 embodiment of springs and wells within 

 the pond bed. In the absence of thor- 

 oughly demonstrated fitness, the more 

 prudent course will be to provide an in- 

 dependent water supply reservoir, appor- 

 tioning its area to the volume of the 

 spring. While being held in this res- 

 ervoir the gaseous contents of the water 

 will be corrected and its temperature 

 seasonably modified. 



The flow from many springs is so ob- 

 structed through the trampling of stock 



or from other causes that they emit only 

 a small portion of the water available 

 near the surface. In such cases the sup- 

 ply may usually be materially increased 

 by sinking 2-foot lengths of terra-cotta 

 pipe over the bubble and removing the 

 incased earth. Several such pipes in a 

 promising area will often result in an 

 astonishing increase in flow. Where the 

 cost is not prohibitive, however, the bet- 

 ter course will be to excavate the site and 

 wall it in with rock and concrete. 



In profusely watered sections — notably 

 in the states bordering the Great Lakes — 

 there are many tracts of marshy charac- 

 teristics, some of them hundreds of acres 

 in extent, promiscuously interlaced with 

 tiny rivulets which combine to form 

 streams of considerable size. Seemingly 

 inexhaustible quantities of water lie 

 close to the surface in many such places, 

 and by driving pipes only a few feet into 

 the ground flowing wells are obtained. 



Where the volume of water is a mat- 

 ter of concern the overflow level of 

 spring reservoirs, sunken tiling or driven 

 pipes should be kept as low as possible, 

 consistent with the object in view, as 

 the flow will naturally decrease with the 

 elevation of the head against which it 

 works. 



A brood pond contiguous to a spring 

 reservoir may be fed through a spillway 

 directly into the stock pond. Where a 

 reservoir is impracticable, at least partial 

 correction of any abnormal condition of 

 the water may be brought about by con- 

 ducting it to the pond through open 

 ditches or raceways of wood or concrete, 

 the choice of material being determined 

 by adaptability of the soil and the com- 

 parative expenditure involved. 



The chief objection to creek or river 

 water as a supply for fish ponds is the 

 great quantity of mud and debris carried 

 during freshets, and the excessive cost 

 of effective measures to prevent its in- 

 troduction into the nonds. Streams sub- 

 ject to extremely high-water periods are 

 totally impracticable as a source of sup- 

 ply, while those of lesser floods can be 

 utihVed only after a considerable initial 

 expenditure, and much vigilance will be 



