244 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



moves landward and would inevitably increase the salinity over tlie 

 areas on which oysters could be planted, and an ofisliore wind would 

 tend to produce a fall in salinity. In other words, the neutral zone of 

 water, just saline enough to be favorable to oyster life, has no fixed posi- 

 tion, but moves shoreward or lakewafd in conformity with the direction 

 of the prevailing wind. 



The rapidity with which these changes may take place is remarkabl*- 

 as illustrated by the following observations made from an anchored 

 boat in Bear Eiver Bay on October 10, 1898 : 



In the last reading the density was too great to be read with tht 

 salinometers used, but it greatly exceeded 1.031. 



A few days later, at the mouth of the Jordan, the density was fouiui 

 to change from 1.009 to 1.0141 within 5 minutes. In both cases there 

 was a lake breeze blowing at a velocity estimated to not exceed 8 miles 

 an hour. The salt water crept into the less salt in long tonguelike 

 streaks, the progress of which could be readily distinguished by their 

 color. 



In Bear Eiver Bay, at 12.30 o'clock, on October 10, 1898, the density 

 near the north end of "The Knoll" on the j)romontory was 1.003, at 

 5.15 o'clock it was 1.011, and at S o'clock next morning it had risen to 

 1.015. The density was, perhaps, higher during the night, as the wind 

 was southerly at nightfall, when the salinity was increasing; but in 

 the morning it had veered to the north, which would tend to blow the 

 salt water lakeward again. 



The " neutral zone" appears to be at all times comparatively narrow. 

 This was best illustrated by observations made at the southern mouth 

 of the Weber Eiver, where the fresh water is discharged over an allu- 

 vial fan. At the edge of the delta, where its slope begins to increase 

 in its deflection from the horizontal, the water was found to have a 

 density of 1.031 in a depth of 1 foot; 50 yards nearer the shore, where 

 the depth had decreased to 7 Inches, the density had fallen to 1.004; 50 

 yards farther on it was 1.002, and 100 yards farther it was but 1.0(i(»5, 

 or practically fresh. The zone of water of a density suitable for the 

 growth of oysters was certainly not more than 25 yards wide, although 

 it extended around the entire rim of the delta. 



At the mouth of Bear Eiver the neutral zone was wider, but the dis- 

 tribution of the salinity was so irregular that it is impossible to state 

 its width. A complication was introduced here by the fact that the 

 density was undergoing rapid change from the effect of the wind, as 

 has been already set forth. 



