Evening star., 1917-01-14

HNHERE is something inherently pic
turesque in large bodies of water.
They seem to reflect and intensity
nature in all her changing moods and
bring to city folk rare sense of lib
Grafton which even the most ardent ad-
vocates of urban life would not readily
forego. Washington is fortunate in
having four large sheets of water.
which. aside from their picturesque
value, render indispensable service as
part of the water supply system OF the
District. Three of these-Dalecarlia
Georgetown and Mcmillan Park reser-
voirs-are under the supervision of the
United States Engineer Corps. which
controls the water supply until it has
passed through the filtration plant at
Mcmillan Park. f. y. Hardy, superin-
tendent of the Washington aqueduct
and filtration plant, recently explained
the use and construction of these reser-
voirs.
The water supply of the District is
obtained from the Potomac river at
Great Falls. A diversion dam, built
short distance above the falls, diverts
the water into a conduit nine feet in
diameter. which carries it for nine
miles to the Dalecarlia reservoir.
This picturesque body of water is sit
uated in a government reservation of
about 800 acres. on the northwestern
boundary line of the District. In it's at
tractive woodland setting, the reser
voir makes a charming picture for au-
tomobilists on the Conduit road. Clus-
ters of pampas grass. altheas and hy-
drangeas grow at intervals along the
nearest bank. and overhanging trees
are reflected in its cool depths. Bass.
carp and perch disport themselves there
in perfect security, protected by the
government from predatory fishermen.
This reservoir was originally formed
by damming the Little Falls branch,
tributary of the Potomac flowing along
the line of the conduit. Although SEEM
ingly a large natural lake, the basin
is lined with rough stone from a point
below the low water line to the top of
the banks The work was begun in
1853 and completed January 3. 1859.
The dates are engraved on the stone
sluice tower at the eastern extremity
of the reservoir.
The surface of the water is over fifty
acres in extent, and the capacity of the
reservoir is 191 100000 gallons, of which
141, 100000 gallons are available for
use. 1t is here that the heaviest sedi-
mentation takes place, SO heavy, indeed,
that in 1909 1t was necessary to dredge
100, 900 cubic yards of mud from the up
per end of the reservoir.
At nearly the same grade, the water
flows on to the Georgetown reservoir.
half way between the Dalecarlia reser-
coir and Georgetown. Situated on
government reservation of about fifty
acres. this reservoir also makes an at
tractive picture. One is Immediately
impressed with the UNCOVERED castle
which guards the eastern extremity of
the reservoir.
This building is used as the insignia
of the United States Engineer Corps
and may be seen on the badges of the
service. 1t is in reality the effluent
gatehouse, and the influent gatehouse,
if less pretentious. is equally pictur-
esque. Here. as at the Dalecarlia reser-
voir, pampas grass is used as an effec-
tive decoration. The reservoir is formed
by an embankment of earth surrounding
favorable site. The walls and banks
are lined throughout with stone and
concrete and the floor and part of the
walls of the sedimentation basin, a di-
vision of the reservoir, are also of con-
crete.
When the river is very turbd, sui
phate of aluminium is introduced into
the conduit at the preliminary treat
ment plant, between the Dalecarlia and
Georgetown reservoirs. This coagulent,
is well as most of the foreign matter