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There were not few rivers that a smell which
garbage and oil float in a surface of a river,
and attaches a nose around 1960 drifted all
over the neighborhood. However, the dirt
of a river or a lake improves now. A problem
like Niigata Minamata disease or itai-itai
disease was also lost. However, dirt was
not necessarily lost. Now, eutrophication of a lake is still progressing. The past several years
are the situation of alternation between
advance and retreat of contamination and
recovery.
Lake Biwa which is the greatest lake in Japan
was severely dirty once. However, the water
stored there is used as drinking water of
a little more than 14 million people who
live in Kyoto, Osaka and the Kobe district,
or Shiga Prefecture. It was the 1970s that
the dirt of the Lake Biwa has come to be
conspicuous. Various drainage came to flow
in as development of the lakefront progressed
and residences, factories, etc. increased
in number. The white bubble of synthetic
detergent spread on the whole surface of a lake, and people were surprised temporarily.
Moreover, drainage became a cause, eutrophication
progressed and red tide occurred here and
there. A cause can be said that the defect
of the action of people who do not consider
an environmental thing, and drainage processing
equipment etc. became the cause. Then, about
the dirt of Lake Biwa, it solved mostly.
The regulations about regulation of factory
effluent or installation of the septic tank
of each home enact a prefecture as a measure.Organic
corruption and eutrophication were getting
worseto prefectural various disposal by earnest
cooperation of the people of the prefecture
.
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