A GREAT SALT LAKE PROBLEM.

Otago Witness, Issue 2399, 22 February 1900, Page 66

A GREAT SALT LAKE PROBLEM.

(Nature. )

An alluring possibility has for a long time attached itself to the economic resources of Great Salt Lake, in the Western United States, in the Avay of establishing in its waters, as permanent residents, forms of marine life of commercial importance. The United States Pish Commission recently made an examination of the lake with a view to determining the feasibility of such a plan. The work Avas undertaken by Mr H. F. Moore, of the Commission, who finds in the peculiarly interesting conditions which prevail in this unique body of water a decisive answer.

Crustacea, insect larvce, and the loAver plant-life abound in its freshei parts, but lor the ordinary inhabitants of the sea the salinity is much too great in the main body of the lake. Great Salt Lake is a remnant of the pro-historic Lake Bonneville, Avlnch ,-was fresh, or nearly so, until its drainage jbasin became isolated by climatic and other 'changes, its salinity then increasing by evaporation. Brackish springs are common in the vicinitj r , and these, with the salts of the feeding streams, still contribute to the accumulation of saline matter. On the ' authority of the United States Geological Survey, the present rate of accumulation .will charge the lake with common salt ■■within a period of 25,000 years. The present density is about 1.168, Avhile that of [the ocean is but 1.025. It appears that it Is not the nature of the saline materials, but their excessive quantity alone, that makes unfit for ocean life ; for the rela-

j tive proportions of the solids in solution do I not differ materially in the lake-water and sea-Avater. Three-fourths of these solids are I common salt in both cases. The lake while ! strongly salt, is not alkaline, and would { presumably support the higher organisms of the ocean if properly diluted. Diatoms have been grown experimentally in the diluted Salt Lake Avater, and, indeed, have been found native in the lake, together Avith other loav plant and animal life, in its brackish parts.

On account of the removal for commercial purposes of large quantities of salt, many have looked forward to a day when the consequent freshening process shall have reduced the density of the water sufficiently to make it an inhabitable medium. About 42,000 tons of common salt are removed annually, while 16,000 tons, accoiding to the calculation of the 25,000-year period required to saturate the lake, enter it each year. From the present density, IJ6B, the luke must now hold about 400,000,000 tons of salt, and with, these .figures as a basics it appears that in 14,000 vearjt — the processes continuing at the present rate — the lake-watei will reach the density of seawater. As this is a far cry into the future, some would believe that the solution of the problem was to be found in acclimatisation of marine forms to the present biiny Avaters. There is no evidence- that this is feasible or remotely possible ; the oyster has the best possible opportunity to adapt itself to salt or fresh water, but clings to an intermediate brackish zone of a density between 1.010 and 1.020. The plan Avhich seemed to offer the only possibility of success concerned the oyster, and the location, near the mouth of the fresh sticams that feed the lake, of water-zones of a degree of

bracklshness favourable to oyster growth. The conditions which were found to exist were such as to show conclusively that there is no hope for the utilisation of the lake in this way.