272
S. Alfi, Y. Argaman and G. Shelef
Alexander Stream. This was done by probes which are capable of measuring D.O.
concentrations as low as 0.05 mg/1.
THE ALEXANDER STREAM
Sampling Points in the Alexander Stream
The watershed area of the Alexander Stream covers approximately 600 km
2 . The
mean annual rainfall is approx. 500—600 mm. concentrated in a winter period of three
months. The Alexander Stream watershed extends from the mountains of Shehem
(Sebastia) in the east to the Mediterranean coast in the west. It is characterized by
relatively steep slopes at the mountainous region which become gentle as it nears the
coast.
Only during the winter months is there a substantial flow of water in the stream.
During the summer (9 out of 12 months) the stream is dry, with the last six kilometers
consisting of sea water mixed with sewage effluents from the city of Natanya.
The points along the stream selected for sampling and measuring (see Fig. 1) were: (A)
Maabarot bridge, where the stream is dry during the summer and has drainage and run-off
water flow during the winter months: (B) the Vitkin bridge, downstream from the
discharge point of the Natanya sewage effluent, where a thick layer of sludge lies under
the supernatant water: (C) Mihmoret bridge, where the high salinity of the water
indicates the strong influence of the sea upon the stream at its extreme western reach.
Sources of Pollution
The first signs of pollution in the Alexander Stream to appear in 1964 were caused by
the discharge of sewage effluent from the Gath citrus canning plant. In 1965 the flow of
treated sewage from Natanya commenced from the south via the Abihail Ditch. Two
years later the volume of sewage effluents entering the stream increased considerably and
in the last five years the pollution has become intolerable and has caused fish-kills and
other nuisances.
In 1968, the Gath plant stopped releasing sewage into the stream and the situation
slightly improved. Natanya has remained the exclusive source of pollution, discharging
alternately treated and untreated domestic and industrial wastes (approximately 6,000 m
3
per day) and the condition of the stream has become quite critical.
The BOD loading on the Stream
The BOD of the effluents entering Alexander Stream is 50-60 mg/1 (when treated) and
240 mg/1 when untreated sewage flows into the stream. During summer, the stream acts
as a long narrow oxidation pond — 4500 m long, 10 m wide and 2 m deep — with a total
loading of 400 kg BOD per day, when treated sewage enters the stream under normal
conditions.
As the most affected area of the stream is the reach around the Vitkin bridge (20 dun.)
the organic load is 20 kg BOD/dun/day under normal conditions. When raw sewage flows
into the stream the loading rises to more than 80 kg BOD/dun/day causing anaerobic
conditions. (1 dunam = 1000 square meters).
S. Alfi, Y. Argaman and G. Shelef
Alexander Stream. This was done by probes which are capable of measuring D.O.
concentrations as low as 0.05 mg/1.
THE ALEXANDER STREAM
Sampling Points in the Alexander Stream
The watershed area of the Alexander Stream covers approximately 600 km
2 . The
mean annual rainfall is approx. 500—600 mm. concentrated in a winter period of three
months. The Alexander Stream watershed extends from the mountains of Shehem
(Sebastia) in the east to the Mediterranean coast in the west. It is characterized by
relatively steep slopes at the mountainous region which become gentle as it nears the
coast.
Only during the winter months is there a substantial flow of water in the stream.
During the summer (9 out of 12 months) the stream is dry, with the last six kilometers
consisting of sea water mixed with sewage effluents from the city of Natanya.
The points along the stream selected for sampling and measuring (see Fig. 1) were: (A)
Maabarot bridge, where the stream is dry during the summer and has drainage and run-off
water flow during the winter months: (B) the Vitkin bridge, downstream from the
discharge point of the Natanya sewage effluent, where a thick layer of sludge lies under
the supernatant water: (C) Mihmoret bridge, where the high salinity of the water
indicates the strong influence of the sea upon the stream at its extreme western reach.
Sources of Pollution
The first signs of pollution in the Alexander Stream to appear in 1964 were caused by
the discharge of sewage effluent from the Gath citrus canning plant. In 1965 the flow of
treated sewage from Natanya commenced from the south via the Abihail Ditch. Two
years later the volume of sewage effluents entering the stream increased considerably and
in the last five years the pollution has become intolerable and has caused fish-kills and
other nuisances.
In 1968, the Gath plant stopped releasing sewage into the stream and the situation
slightly improved. Natanya has remained the exclusive source of pollution, discharging
alternately treated and untreated domestic and industrial wastes (approximately 6,000 m
3
per day) and the condition of the stream has become quite critical.
The BOD loading on the Stream
The BOD of the effluents entering Alexander Stream is 50-60 mg/1 (when treated) and
240 mg/1 when untreated sewage flows into the stream. During summer, the stream acts
as a long narrow oxidation pond — 4500 m long, 10 m wide and 2 m deep — with a total
loading of 400 kg BOD per day, when treated sewage enters the stream under normal
conditions.
As the most affected area of the stream is the reach around the Vitkin bridge (20 dun.)
the organic load is 20 kg BOD/dun/day under normal conditions. When raw sewage flows
into the stream the loading rises to more than 80 kg BOD/dun/day causing anaerobic
conditions. (1 dunam = 1000 square meters).