Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-07-13
TURBIDITY OF WATER
RECORD FOR JUNE COMPARED
WITH PREVIOUS MONTHS.

according to Capt Cosby the engineer
oncer in charge of the Washington water
supply system. in a report to Gen. Macken-
xie. chief OF engineers, the river water at
Great Falls was much more turbid during
June than during any preceding month
since the filters were put in service. Be-
tween June l and 1S the turbidity varied
between IS and 800. after which it suddenly
rose until the 23d it had reached LOO as a
maximum 1t then gradually fell to SO, the
3oth- BY closing the gates at Great Falls
for four days between the 10th and 26th a
great deal Of this excessively muddy water
was shut out Of the aQueduct system. Ow-
Ing to the lack of sufficient storage capac-
lily In the reservoir however, 1t became
necessary, says Capt. Cosby, to open the
gates before the river water had become
clear, and consequently considerable muddy
water passed into the reservoir and later to
the filter beds
The maximum turbidity of the water at
Dalecarlia (receiving) reservoir was 500;
at georgetown reservoir, $50. and at the
washington city reservoir, 100. Capt. Cosby
says those turbidities We're much greater
than any experienced since the filters were
started and with the accompanying organ
isms in the water clogged the filters very
rapidly In fact. the loss of head, he says,
increased as much in few days as 1t did
In the same number of months during the
winter and spring. AS consequence OF
eliic CiOkSiHS OI the HittTS II WdS
with considerable difficulty that they were
kept In service and the work of cleaning
had to be pushed day and night. The city
water had noticeable color during the last
four days of the month.
Few Bacteria in Filtered Water.
notwithstanding the increased number
of bacteria IN the river and reservoir wa
ters." Capt. Cosby says, 1.-The bacteria have
remained remarkably low in the filtered
city water, the maximum on any day hav-
ing been only thirty-six per cubic cent?
meter. The bacillus coli were frequently
found In the samples of water from The
several reservoirs. in only one case in the
filtered water reservoir, and in one out OF
-thirty-two samples taken from taps In va
rfcus parts of the city. During the first
and greater part of the month the aka
| Unity and hardness remained high but for
| the latter part they were considerably low
| cred by the diluting effect Of the heavy
transforms.
Owing to the higher temperature, which
accelerated the growth of the bacteria and
heterogeneous on the surface OF the sand,
and later to the unusual turbidity of the
applied water, the runs were terminated
quite abruptly and are generally shorter
than for last month. The cost, $S.1S, for
operating the plant per million gallons fill
! tered was greater this month than for any
previous one. This increased cost was due
| to the washing of large amount of sand
that had been wheeled out of the beds
during previous months, to the cleaning OF
| a greater number of filters and to the en-
| ploymen of new men who were unaccus-
toned to the work. Even so, the expense
was less than at other plants In this coun-
| try operated under similar conditions.