30 



BULLETIN 61, U. S. DEPARTMENT OF AGRICULTUEE. 



The eodiiim-potassium ratio has been discussed in another section. The calcium- 

 magnesium ratio shovrs a marked decrease for the lake waters as compared with river 

 waters. This can be explained by the fact that calcium readily precii^itates as car- 

 bonate or sulphate, or may be removed by the agency of vegetable organisms \ The 

 removal of calcium would leave the magnesium m greater relative amount. There is 

 no doubt that magnesium is also precipitated as a carbonate, but is not eliminated at 

 as great a rate as calcium. Chlorides are more abundant than sulphates in the lake 

 waters as compared with river waters. This is undoubtedly due to the precipitation 

 of the sulphate radical by lime. Carbonates and bicarbonates are in less relative 

 proportion in lake waters than in river waters. This is accounted for by the precipita- 

 tion of calcium and magnesium as insoluble carbonates. 



Borates are conspicuous in Owens, I^Iono, and the lakes of southern Oregon. The 

 waters of Owens Lake are noteworthy on account of the content of nitrates and arsenic 

 compounds. 



Certain regional characteristics become noticeable in a comparison of the chemical 

 content of lake waters. The lakes of the Bonneville Basin are conspicuous for their 

 lack of carbonates and bicarbonates and their high content of chlorides. Sulphates 

 are present, but in moderate amount. The high content of these lakes in salines is 

 to be noted also. The regional rocks of the Bonneville Basin are, for the gi'eater part, 

 eedimentaries. Limestones are common. 



The lakes of the Lahontan Basin have a much lower saline content, and contain 

 chlorides, sulphates, and carbonates. Chlorides usually dominate, but in PjTamid, 

 Winnemucca, and Humboldt Lakes carbonates are somewhat greater in amount than 

 chlorides. The regional rocks are characterized by a greater area of igneous rocks 

 than the Bonneville Basin. 



Owens and Mono Lakes contain chlorides and carbonates in greatest amount. Chlo- 

 rides are greater in amount than carbonates and sulphates are least. These lakes are 

 characterized by a high saline content. The regional rocks are predominatingly 

 igneous. The southern Oregon lakes are low in sulphates and have about eqtial 

 amounts of chlorides and carbonates. In the case of only one lake are the chlorides 

 exceeded by the sulphates. The regional rocks are igneous. 



ANNUAL SALINE CONTENT OF RIVER DISCHARGES. 



The rat'e at which salines are accumulating at present in the basin lakes can be 

 calculated approximately from the mean annual flow of the principal rivers and their 

 saline content. As has been mentioned before, the chemical data are insufficient, 

 and, consequently, the conclusions give only approximate results. It is belicA-ed 

 that the figures are conservative and rather under than overestimates. In Table XVI 

 (Appendix ) are given the tons of salines discharged by the Owens, Humboldt, Truckee, 

 Walker, and Bear Rivers. The total salines discharged by these five rivers into their 

 lake basins is 1,692,153 tons per annum. 



An approximate determination has been made for four basins and is given in the 

 accompanying table: 



Discharge of aalines into four impcrtant laJce basins. 



Basin. 



Total 

 run-ofl 



per 

 annum 

 for basin. 



Rivers tATJical of run- 

 off water. 



Mean 

 annual 

 flow of 



these 

 rivers. 



Ratio of 



total run- 



ofito 



flow of 



rivers. 



Salines 

 discharged 

 per annum 

 by rivers. 



Total 



salines 



discharged 



per annum 



into basin. 



Bonneville 



Sec-feet. 

 3,583 

 2,406 



306 

 724 



Bear 



Sec-feet. 

 1,860 

 1,504 



306 

 1,030 



1.9 

 1.6 



1.0 



.7 



Tom. 

 1,259,235 

 286,019 



102,228 

 155,335 



Tons. 

 2,392,546 



Lahontan 



Walker, Humbolt, 



and Truckee 

 Owens 



457,630 



Owens 



102,228 



Southern Oregon lakes 



Truckee 



108, 734 







J Bui. No. 108, U. S. Geol. Survey, p. 94. 



