248 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



During the writer's visit to Great Salt Lake lie several times heard 

 the opinion expressed that the extraction of salts from the lake through 

 the several agencies acting in that direction would in time result in a 

 reduction of its density to a degree which would solve the problem of 

 the introduction of marine forms. 



Salts are deposited by the lake principally in three ways: {a) by 

 desiccation on the flats covered by the water during stages of elevation ; 

 (b) by supersaturation, especially at reduced temperatures and low 

 stages; (c) by human agencies in the process of salt-making. 



In times gone by, when the lake was undergoing rapid shrinkage, 

 quantities of salts, great in the aggregate when we consider the area 

 involved, were left upon and in the soil of the exposed bottom, and even 

 during the comparatively small shrinkage between 1869 and 1898 an 

 appreciable quantity of the lake's saline constituents was left upon the 

 flats. In some cases these materials are so entrapped in the soil that 

 they are not again readily dissolved, but a considerable quantity is, under 

 usual circumstances, returned to the lake by leaching. Common salt 

 is also thrown down in places along shore by the concentration of the 

 water on the shallows by evaporation. 



Certain of the saline contents of the water are but sparingly soluble, 

 and the addition of the annual increment from the inflowing streams 

 causes supersaturation and consequent precipitation. This is the case 

 with carbonate of lime, which is thrown down as oolitic sand, and 

 sodium sulphate, which is cast ui)on the shores in winter when the sol- 

 vent i)roperties of the water are reduced by its low temperature. The 

 sodium sulphate is largely redissolved when the temperature of the 

 water rises, but there is doubtless a constant loss due to the mechan- 

 ical mixture of some of it with sand and mud thrown up by the waves. 

 It is sometimes collected along shore in winter for commercial purposes. 

 The amount of saline matter annually lost to the lake through the 

 agencies just discussed can not be estimated, and the opinion as to the 

 future adaptability of the lake to marine organisms was not based upon 

 these agencies, but upon the removal of salt for the use of man. See- 

 ing the great quantities of salt at the salt ponds and not appreciating 

 the vast stores of the lake, the mistake is not unnatural. About 50,000 

 tons of salts are annually taken from the lake for commercial purposes, 

 but less than 84 per cent, or about 42,000 tons, of this is sodium chlo- 

 ride. Basing the calculation upon Gilbert's estimated accumulation 

 period of 25,000 years, the annual influx of salt from the tributaries of 

 the lake is about 16,000 tons, making the net loss about 26,000 tons. 

 The lake at present holds about 400,000,000 tons of common salt, with 

 a water density of 1 .168. A greater density than about 1.020 is not 

 favorable to the oyster, and to reduce the lake to that degree of salinity, 

 its volume remaining unaltered, would necessitate the extraction of 

 about 300,000,000 tons of sodium chloride, and at the present rate of 

 loss this would require a i)eriod of nearly 14,000 years. It is not con- 

 sidered that the prospect is such as to require very serious attention at 

 present and the niceties of computation have been neglected. 



