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13.
Water Supplies.
A hard, pure and constant piped water supply is provided
by the Metropolitan Water Board; the supply has been satisfactory
in both quality and quantity.
Rivers and Streams.
Eight visits we re made during the year in connection with the
pollution of water courses. Informal action secured the abatement
of minor instances of pollution.
Fly Nuisance.
For some years past, residents on the western boundary of the
Borough have suffered considerable fly nuisance in the spring and
the year under review proved no exception; indeed, from the
evidence at present available, it would appear that this section
of the community must expect an annual recurrence of this irritating
and annoying experience.
Two types of fly are involved and both, fortunately, are nonbiting
and are judged to be harmless from a medical point of view.
The first fly to emerge is the Anisopus Fenestralis which, because
of its predilection for breeding in sewage filters, is thought to be
wind-borne from a large sewage disposal works in an adjoining Borough.
The advice of the Water Pollution Research Laboratory of the Department
of Scientific and Industrial Research has resulted in the
treatment of the filters early each year with liquid gammexane and
this has done much to mitigate the nuisance.
The second fly, Genus Chironomidae (species Tanytarsus and
Chironomus) is known to emerge from the waters of the two large
Metropolitan Water Board reservoirs and causes considerable annoyance
and discomfort, largely by reason of the myriads of flies which
hover about the heads of residents, cluster around doors and windows
and generally invade houses. Owners of property in the vicinity of
the reservoirs would be unwise to contemplate re-painting until
after the emergence of the flies.
As the larvae of the fly breeds in the water of the reservoirs,
no practical means of control have yet been established, although
the Metropolitan Water Board is actively investigating the matter.
Once the flies have emerged, however, the prompt and thorough
spraying of the banks by the Board with D.D.T. solution has
secured an effective but somewhat costly abatement of the nuisance.