138 GUIDEBOOK OF THE WESTERN UNITED STATES 
from 25 to 150 feet below the surface. A large area is underlain by 
the water-bearing beds, but the largest volume at moderate depth 
is found about Deming and in the lower part of the wide bolson 
extending southward from that place along the west side of the Flo- 
rida Mountains (flo-ree’dah). It is believed that the water is an 
extension of the underflow from the Mimbres River with additions 
from confluent streams, and there is some increment from the local 
rainfall, which amounts to about 10 inches a year. Although most 
of the rain water evaporates, a certain proportion passes underground 
where the soil is porous. There is, however, a return of part of this 
water to the surface by capillary action, which is strong in arid regions. 
The volume of water stored in the valley fill is great, but it is well 
known that such a supply can be depleted if it is drawn upon more 
heavily than it can be replenished. To ascertain these conditions 
a careful investigation was made by the United States Geological 
Survey,* cooperating with the State of New Mexico, to ascertain 
the amount of water available. It was estimated that the average 
annual increment of the ground water during 20 years was from 10,000 
to 11,000 acre-feet, with a high rate in wet seasons, and therefore 
that this should be the limit of its utilization. The rate of movement 
down the valley is mostly from 2 to 3 feet a day. Heavy pumping 
reduces the level of the underground water table. 
Irrigation by well water began in 1908, and in 1914 nearly 200 
pumping plants had been installed or were under erection. As 
most of the operators were inexperienced in agriculture many of the 
projects were not profitable, and in 1919 only 25 pumps were in 
operation. In 1930 there had been considerable revival of the in- 
dustry, and 116 pumps were supplying water for irrigation and other 
uses, and about 6,000 acres were under cultivation, mostly with very 
satisfactory returns. The water is generally less than 50 feet below 
the surface and is pumped with small gasoline engines, with a yield 
of 200 to 1,000 gallons a minute. Various crops are raised, including 
a large acreage of beans and considerable alfalfa. The amount of 
water necessary varies with the soil and crop, but 2 to 2% acre-feet 
to the acre is used. A well producing 500 gallons a minute can itti- 
gate 25 acres in about three days, but this must be repeated several 
times during the growing season. 
The wide desert about Deming, known as the Florida Plains, is 
a part of the valley of the Mimbres River (Spanish, mimbres, water 
willow), past and present. It is heavily covered by valley fill, the 
bottom of which appears not to have been reached by borings 710, 
980, and 1,665 feet deep in Deming and vicinity. Out of the level 
surface of this plain or valley rise several high mountains and ridges, 
such as the Florida Mountains; the Tres Hermanas Mountains, 
* Results given in U, S, Geol, Survey Water-Supply Paper 637—B, by W, N. White. 
