The: Waters oe the Rio Grande 39 
this section, for it has long been known that there are occurrences of 
pure sodic carbonate within its limits. I do not know who first dis¬ 
covered it. Attempts have been made to prepare and market it. It 
matters but little to the facts in the case whether we have any expla¬ 
nation to offer for them or not, the facts remain just the same, i. e., 
that the aitesian waters in this section are rich in sodic carbonate, and 
the people who live in this section have observed that these waters are 
not good for irrigation. 
Concerning the use of these waters for irrigating crops, Dr Sieh- 
enthal says: “It seems to be pretty generally agreed, however, as the re¬ 
sult of experience, that the dark water is nowhere as good as ditch water 
and that in many places it is positively harmful and should always, if 
posible, be used in conjunction with ditch water. Its moderate use is likely 
to cause a “case-hardening”, or the formation of a hard crust on the soil 
surface. In any event, even if one application is not injurious, its continued 
use in subirrigation will surely impregnate the soil with alkali.”* 
We shall have occasion to return to this subject for a fuller con¬ 
sideration of the conditions and facts as they have developed during 
the past 20 years. 
THE SAN LUIS LAKE WATER 
There still remains a small body of water which is entitled to 
consideration. This is the San Luis Lake which presents a surface 
of a little more than one square mile and has an average depth of 15 
feet under ordinary conditions. This is the statement usually made. 
I have no other knowldge as to the depth, which varies with the season 
and is greater some years than others. There are several lakes, but 
only one of them has any considerable size, which is the San Luis 
Lake. This lake is peculiar in that it has no outlet, though the last 
time that I was there I was told that it was overflowing on the west 
side. There was a condition of affairs at this time that I had never 
seen before though I have been there often. The land to the west of 
the lake for a distance of quite two milesi I would judge, was, for the 
most part, under water. This water, I was informed, was from the 
tailings of the irrigating and drainage ditches and water flowing out 
of the lake. I can not well verify these statements. This lake not only 
has no- outlet, it also has no visible inlet except at rare intervals, when 
the waters of the Saguache and San Luis creeks flow overland into it. 
I have been informed that this happened but once in 40 years pfior to 
1909 and I was also informed that it had happened once in 21 years 
i • prior to that time. These two statements are of course not contra¬ 
dictory. The persons giving the information may have referred to 
the same occasion. Be that as it may, it is evident that this is a rare 
occurrence. The Sagauche and San Luis creeks, especially the Sagu¬ 
ache, would be classed as mountain streams and undoubtedly carry 
*C. E. Siebenthal. Water Supply Paper No. 240, IT. S. Geo. Survey, p. 115. 
