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Report of the Medical Officer of Health. 31
The main stream from the weir to the point where the combined
effluent enters it is very foul, and should be thoroughly
cleansed at once. On the 5th April the River at the weir was
found to be 15 inches below its normal level and inches below
the weir. There was about 12 feet of mud exposed on the north
bank, and about 8 feet on the south bank.
Steps should be taken to ensure that this part is periodicallv
scoured by the release of the main body of water above the weir.
From this point to Messrs. Pimm's Mills the River is in a
very bad condition, due to the excessive amount of sewage in the
water and the depositing of sewage sludge.
From these Mills to the River Thames the Wandle has a
more rapid flow, and there is not so much obvious pollution.
The effluent from the Wandle Valley Sewerage Board's
Farm is at present very foul, and has a distinctive sewage odour
for some distance from the point of discharge.
Although there is a coke screen for filtering purposes this
makes little or no difference, and quantities of sewage fungus
pass into the River. As this Sewage Farm disposes of the sewage
of about 60,000 persons, at least 1,200,000 gallons are here
discharged into the River daily, and lower down the effluent from
the Wimbledon Sewage Farm, which deals with the sewage of
another 60,000 persons, or 1,200,000 gallons, also' discharge into
the River, making a total of 2,400,000 gallons. This latter
effluent is at present fairly clean.
When this amount is added to the amount of effluent from
the County Borough of Croydon, which enters the River Wandle
near Beddington, and which has a population, including
Coulsdon and Purley, of about 200,000 persons, and discharges
about 4,000,000 gallons of sewage, it makes the total amount of
sewage discharged into the River about 6,400,000 gallons daily.
This, in my opinion, is a minimum estimate, as I have allowed
20 gallons as the daily amount of water per head of population,
instead of 30 gallons, as estimated by Dr. Thresh.