Coeur d'Alene evening press. (Coeur d'Alene, Idaho) 1907-1929, 1910-04-01
19Os-lseo second feet.
Mean-ts7O second feet.

Il
much II is impossible to say. Al
measurement at Spokane and at
Spokane bridge October /. 1895 shows
respective discharges OF 1890 and
sos second feet. 1t Is more than
likely that q large part Of this diff
ference Is due to artificial control
since the Post Falls plant was In OPP
Grafton at that time. In my opinion
1t would be reasonable 10 say that
the flow at Post Falls il rs per cent
less than at Spokane. On this basis
the natural average low water fiow
at Post Falls may be taken as 1879
second feet.
/ This naturally limits the capacity
OF any plan for 1t is seen that In dry
years the low water flow is % per
cent less than the average.
i Now, the company has installed
ave generators rated at 1850 XIV.
each or 1890 horsepower on the
turbine shaft. This would require n
fiow Of $3.50 second feet under so
foot head. When there is plenty Of
water available these units are fire.
Quently overloaded so per cent for
few hours each day. When water IL
scarce. /. e., after the storage water
Ia exhausted they are not able 70 run
all the units. ton October 81 OF the
] present year visited the plant. Three
units were running and they were
not under full load. This was due
to scarcity Of waterl.
The company was justified in
building the plant OF considerably
greater capacity than merely neces-
sary to utilize the low water flow for
tAo principal reasons:
II % The plant forms one OF a
system OF plants both steam and wat.
er power that are all connected such
that power can be drawn from them
in any manner desired. The steam
plant is used to tide over shortage
on the water plants. The extra ca
pacity the company would be justified
in Incorporating In the Post Falls
plant on this account will therefore
depend on the relative cost OF steam
. and water power with maintenance,
, interest, depreciation. etc, figured on
a yearly basis for both.
(2) A certain amount OF water has
been stored In Occur d'Alene lake and
held over until the low water season.
J The increasement IN the plants "a
pacity that is due 10 the ability TO
/ use stored water is the only one that
will be considered and its effect on
; the Post Falls plant alone will be
t taken into account.
II is impossible to arrive at more
: than an approximate solution OF this
} problem with the data in hand. do
: not have the area Of the lake and
hence can only guess at the stored
) water. / have estimated from such
t data as are at hand that the lakes
t area at elevation 2126 is at least
: 42,50O acres.
The low water surface OF the lake
: is about at elevation 2l20 and the
. area at this elevation Is at least 26,-
. 500 acres. II il possible to store 8
/ feet Of water over $4,000 acres. As
I sumo 2 feet will be lost by evapora-
Q ton and we have stored $4,000 acre
g feet. II this Is utilized during four
4 summer months II will be equivalent
: TO a uniform flow OF 575 second feet
r and will develop under so feet OF
head 261O horsepower at the turbine
e shaft. The rated capacity Of the
z plant would have to be reduced BY
; this amount Also the present ca
s pacity would be reduced about S.
e per cent II stored water was not used
: by reason OF their being required tf
q operate under AZ feet OF head instead
OF so.
ri Leaving consideration OF any Othei
g plants out OF the question the priyil
y eye OF using stored water alone I
= seen TO add 1850 horsepower to th'
q rated capacity of the plants. II Is Inn
e possible 20 say what this Is worth bu
d It doubtless brings an annual rev
= enue to the company of $50 pc
horsepower per year. The loss 0
% this privilege. therefore. would rep
II resent a reduction in revenues 0
J: S1O7 900 annually.
6. The method Of operating fh
dams at Post Falls Is as follows: Dur
ing the spring rise the fainter gate
are opened wide and the Bear Ira
dam Is lowered. The dam l. left l
this position until the reeeding waite
reaches an elevation OF 2l26 or less
then the Bear Trap dam Is raised an