The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1923-01-04
CHAPTER III.
Transmission Losses and Return
Flow

, Transmission Losses and Return
5 Flow
These two subjects are so init
mately connected that it seems bes
, to discuss points two and three to-
gether.
} Until further information is OBJ
tanned upon river characteristics as
t affected by the conveyance of stor-
age water, more or less empirical
| methods must be used in making the
: adjustments between the interests
, involved. The studies which were
made by the U. S. Geological Sur
!, vey, during the 1917 and 1918 sea-
sons, furnish much valuable ma
: terial and throw considerable light
upon the problem, but the field in
: vestigations have not extended thru
sufficient range of time to warrant
definite determination of losses
I based entirely upon the facts col
lected. Mr.. LeRue's studies in 1909
and 1910 were based on rather
1 meagre data and can hardly be
! taken as an index of present condi-
tions. A report made by Messrs.
Baldwin and Blossom, following a
| reconnaissance of the river for the
purpose of locating gaging stations,
was general in character and not in
tended to be determinative of the
problems outlined therein.
The evidence is fairly conclusive,
however, that the Snake river like
many other streams, after it leaves
the head water areas which are
highly productive of water, consists
of sections in which loses occur,
| alternating with sections where the
river gains. When the underlying
formation is coarse and porous the
ground-water finds easy passage,
and the water table may dip below
the stream-bed and so continue for
miles. In such sections the river
loses water. In lower stretch of
the river a change in formation af-
fecting the ground-water movement,
or change in river grade, or an in
crease in ground-water supply from
irrigation, may cause the water
table to rise until it is higher than
the river water level, resulting in a
gain to the stream. The losses oc-
curing in one section of the river
help to make the gain in the next
sections below and there is probably
little absolute loss affecting the
water users until a point is reached
so far down stream that water lost
does not return to the channel at
sufficient elevation to be available
for diversion.
The location of gaging stations on
a stream like Snake river is arbi-
trary with respect to ground water
conditions, and it could only be CO.
incidence that discharge measure
ments at any two of these stations
would correctly express gains or
losses in the section between them. |
There might be both gains and |
losses in each section as limited by
the gaging stations, and the meas
urements therefore would only show
net gains or net losses.
The reports of the Investigations
of 1917 and 1918 show net gain
in the section between Moran and
Alpine. 1t is therefore evident that
the water table adjacent to the
river is in general at higher eleva-
ton than the water surface in the
river and drains into 1t at fairly
rapid rate. A certain amount Of
bank storage is created by food con-
ditions on the river. This ground
water drains out quite rapidly as
the river recedes, but its inflow is
checked by the release of storage in
large quantities, the rise in the
river causing fatter slope upon
the water table and consequently a
slower velocity of ground water
An increase in the gain
after storage is cut out of the river
indicates that the bank storage re-
turns at that time. 1t therefore ap
pears that the only final losses
stored water can sustain in the sec
ton from Moran to Alpine are the
increased evaporation losses result
ing from the larger water surface
area of the river due to the convey
ance of a greater volume of water.
AS the river banks thru this section
are relatively steep, the increase in
width due to carrying storage is
very slight and the evaporation
losses resulting from an augmented
practically negligible. A
portion of the bank storage created :
by flood stages early in the season
returns to the river on the dropping
stage during August and is available ..
to natural flow users at a time
when it is greatly needed, but the ,
greater part does not return until
he river recedes to it's normal stage :
after delivery of storage ceases, at !,
which time it is of little material
value to the decreed rights in the ..
Idaho Falls valley. The measure
nents show that river bank storage !,
to about $50 acre feet :.
n 1917 and 300 acre feet in 1918
'eturned to the river when release
If storage ceased, and as an adjust i.
nents of this temporary loss it is !.
suggested that decreed normal flow .
lights be permitted to divert say ,
800. acre feet additional supply y
pread over period of about week
lfter the introduction of storage to
he river and that the same amount
'e returned to stored water users I
Turing the last week that stored I
vater is in the river.
The situation as shown by the a