JANUARY, 1911. MONTHLY WEATHER REVIEW. 131
2 feet higher than had ever before been known. hIany homes were surrounded by water ancl tlie occupants coni-
pelled to abandon them. One resitlence was carried away.
The transformer st at ion, from wliicli electric power for tlie
city is distributed, was practicnlly wrecked, aiitl the city
was left in darkness. Almut 65 feet of track was \v:i4ied
out on tlie Oregon Short Line Railroad near Ikoni. abow
Pocatello, causing a complete stopyiige of traflic un this
roacl for more tlian three days. Hiinclretls of cars tind
almost a thousand passengers were li~lcl nt Pocntello.
Most of tlie wagon tiridges on tlie Port Neiif were vnrritvl
awa~7 or badly claniagetl. The river I)egnn t o fall on
February 4.
THE ~IINIDOIL~ IRRIGATION PROJECT.
By Hon. F. S. 1% ETMIOUTH, Supervising Engineer, United States Reclamation Service.
The hlinidoka irrigation projec t of t8he Unitecl States Reclamation Service covers an irrigable nrett of approxi-
mately 125,000 acres in Lincoln antl Cassia Counties, Idaho, deriving its water siipply from the Snake River
by means of a rock-fill di\-ersion daiii located t i t a point
6 miles south of the Rhidoka stabion on the Oregon
Short Line Railroad.
Tlie gravity portion of this project was construc tecl
during the years 1905 to 1907, and was officially opened
in the spring of 1907. From 190s to the present time
tlie pumping unit has been under construction. This latter unit has not yet been officially opened by the
Secretary of tlie Interior, but water hns been furnished during the season of 1910 on a rental basis to all settlers desiring i t . Tlie character of tlie land lying on the nortli side of
the river varies from sand t,o sandy loam and clay, underlain, a t depths of from 100 to 200 feet, by lava
rock. On the south side of tlie Snake River tlie soil is
more nearly uniforni, consisting of a finely clisinteg-ra tetl lava forniation, mi th a gently rising slope southward
from the river to the foothills of the Goose Creek Rfoun-
tain Range. All tlie tract is free from rock and lias
proved very fertile, growing bountiful crops of staple products. Under tlie existing plan all of the area lying on the
north side of the river, within the limits of the project,
is irrigated by a gravity system, wliicli diverts water for GS,500 acres a t the clam above mentioned, the divert-
ing canal having a capacity of over 1,400 seconcl-feet. This main canal is 13 miles long, and separates a t its
lower end into two great systems, each of which divides
into smaller canals and laterals. At tlie south-side l i e d gates 8.50 second-feet are
diverted into a canal which irrigates by gravity 7,500 acres in its length of 13 miles and which serves also ns a
feeder for the pumping tract, located beyond its lower end. Here t h e e pumping sta tions, eqiiippecl with elec-
trically driven centrifugal lit111ips and operated 1)y
power transmitted from the ~1 ~1 1 1 , rnise water into three main canals, each of which is apl)roxinintely 30 feet
higher than the one below, nittlring tlie greatest lift above tlie gravity canal about 90 feet. With the equip-
nient as at present plnnnetl 500 second-feet of water
passes through tlie first lift station, 3'75 second-feet
through tlie second station, antl 300 secontl-feet through
tlie third, there being a total of 49,500 acres of irrigable
land under this tract.
Tlie farm units on tlie hlinicloka project are 40 and SO
acres in area, nncl the duty- of water is 60 to 100 acres
to the seconcl-foot, according to the character of tile soil. The tract lyiiig on the north side of the river is now
being yroricled with a clrainng-e system, which will
eventunlly serve it11 portions of the land requiring drainage.
The mean annual run-oft' of the Snnlie River a t tlie Minidola clttni is alioiit 6,0~)0,1)~)0 acre-feet, the lowest
on record lwiiig 3 ,SOU,OOO acre-feet. During the years of lorn suninier run-off the nntiiral flow of the river daring 1% portion of tlie irrigating season is not sufficient
to supply tlie needs of the project, on account of prior
rights below, and for that reason storage works have
been provided to giiartl against, any possilJle shortage
clue to a low stage of the river. These storage works l i d i e the project 1witcticdy inclel)enclent of the condition
of the river during tlie irrigation season.
The hlinitlokn d u m is of the rock-fill type, suppleniented
h - an earth fill on the upstream side, nncl is 650 feet
long, averaging a1)out 50 feet in height. At its north
end are locntecl the heavy concrete head gates for the nort,li-sitle ciinal system. A spillway of gravity concrete
section, 3,400 feet long, extends across the river cliannel to the south l~ank, where i t is f l d i e t l by tlie hettrl-gate
structure for the cnnal serving tlie lnntls lying on that side of tlie projetit. Adjoining the nortli-sitle lietit1 gates
on tlie south is t>lie power station, rei-ently completed
which with its prebent eqiiipiiient iq capable of generatin::
9,OOC) horsepower, utilizing tlie lieatl of water created by tlie clam as the source of energy. This head is approxi-
mately 4(j feet, ant1 power is generated by inems of
fire turbine generators of the latest type. Power is
fiirnislied also for coiiiriiercial prposes, heat, ancl light
to tlie towns on the project a t very rensonnhle rates.
Tliis power and liiiniping system constitutes tlie largest hydroelectric piiiiiping plant for irrigation in the world.
Lake Walcott, formed hy the clirersion dam, is a very
attractive body of water, 32 miles in length and froin one-lidf to 3 miles wide. By means of the piers con-
structed on the crest, of the spi1lw:ty storage of ahout
55,000 acre-feet is effected in this 1:tke for w e durinq tlie low-water lwriod of tlie river. This, however, is
merely supplementary to tlie storage at ,Tackson Lake,
Wyo., on the hentlwiters of tlie Snake River, where a
concrete darn of reenfortd type, now under construction,
will impoiiml nearly -IOO,OO( 1 acre-feet of water. thus pro-
viding for any possible contingency with refprence to a
sliortnge of supply. Tlie construction of tlus dam will
be sufIicient,ly advanced hy the season of 1911 to permit
of siifticient storage for tlie project for that year. There are a t present t h e e towns on tlie project,
Rupert, Heyburn, nncl Burle-. tlie two first, named being Government town sites, and all hearing s i p s of activity
and prosperity. The Rliniclokn c ! Soil thwestern lirancli
of the Oregon Short Line Rdroatl passes tliroiigh all these towns. Branch lines from Rupert to Bliss and from Burley to Onldey are under construction. With
the ewelition of a comparatively small amount of State laiitl, as yet unsol~l, practicnlly all of the laud under this
project lias heen filed upon or is in private ownership,
and the clerelopnient of tlir trac t during the present
season has been very rapid, iiidicatilig that within a few
years this section of tlie Snake River Valley will undoubt-
idly beconie a great agricultural center.