russell.] ARTESIAN WELLS. 179 
evidence we now have on this point is the meager records of the drilled 
well in Bruneau Valley. The wells referred to show not only that 
pervious beds occur beneath impervious beds, but that water under 
sufficient pressure to force it to the surface is present. Several hot 
springs also suggest the same conclusion. 
My judgment, based on all the facts accessible, is that the Lewis 
artesian basin is of large size and well worth careful testing by means 
of the drill. The extent of the basin west of Elmore County is 
unknown, and the assumption that it is a closed, basin and reaches the 
Idaho-Oregon boundary is based on a general knowledge of the geology 
of southwestern Idaho and the fact that Snake River below Weiser 
is flowing over impervious rocks older than the Payette formation. 
As to the height to which the water will rise in the artesian head, 
the only basis for judgment at present is the surface elevation at the 
flowing wells in Bruneau Valley. None of these wells, so far as I have 
been able to learn, are tightly cased, and they probably do not show 
the full height to which water would rise under more favorable con- 
ditions. By aneroid measures, the artesian head shown by the wells in 
Bruneau Valley is, as previously stated, at an elevation of about 2,750 
feet above the sea. The method of measuring by means of aneroid 
barometers, the only one I was enabled to employ is, as is well known, 
defective, and the elevation just given may be a hundred feet in error. 
With the assumed height to which water will rise, artesian wells may 
be expected to be successful at any locality west of the mouth of Clover 
Creek at least as far as the eastern boundaiy of Ada County and the 
southward prolongation of that line across Owyhee County, where the 
surface elevation is less than 2,750 feet. The land which is below 
this level is situated in the canyon of Snake River in Bruneau and 
Little Valley. So far as can now be judged, there is no hope that 
water under sufficient pressure to rise to the surface of the plains 
bordering the canyon and valleys just named, is present, but this is a 
matter that should be determined by experiment. 
In order to test the predictions based on geological structure, etc., 
a pioneer well should be put down, with all the well driller's skill that 
can be commanded, at the most favorable locality, and a careful record 
kept of the strata passed through. It is unnecessaiy to add that the 
pressure of each water supply reached should be accurately measured. 
Favorable places for such a test well occur at several localities in the 
vicinity of Snake River, between the mouth of Clover Creek and the 
east boundary of Ada County and in the lower portion of Bruneau 
Valley. I would name, especially, Glenns Ferry and Bruneau. In 
the absence of accurate topographic maps, it is impossible to state at 
what depth water should be reached, but what is scarcely more than a 
guess places it at between 500 and 700 feet. The demand for water 
is so great, however, and the conditions, so far as can be judged from 
