430
20,000 families, including fi shermen, paddy cultivators and vegetable growers, living on the outskirts of Calcutta City, depend on these wetlands
for their livelihood. These wetlands are highly
effi cient oxidation waterbodies for treatment of
domestic sewage.
Threats
Reclamation of a large portion of the wetland
(measuring about 5,000 ha), for agriculture and
urbanisation, is a major threat from real estate
interests.
Conservation
Some of the conservation initiatives and measures are as follows: (a) Proclamation of an
injunction by the Hon’ble Calcutta High Court
(HC) on the basis of a writ petition fi led by an
NGO named ‘People United for Better Living in
Calcutta (PUBLIC)’ restraining the state government from any further reclamation of any portion
of the wetland for commercial and recreational
purposes. (b) All the wetlands of East Calcutta be
declared as being of national signifi cance and be
brought under protection. However, they were
later designated as Ramsar wetlands on 19
August 2002.
20.3.23.5 Mirik Lake in Darjeeling
Himalayas
Mirik Lake (also called the Sumendu Lake),
lying at 1,767 m MSL, between 26° 54′ N and
83° 13′ E, is an artifi cial reservoir of Mirik town,
which was constructed in 1979, under ‘Mirik
Tourist Project’, primarily for the facilitation of
commercial tourism in Darjeeling. The lake is
situated in Mirik area in the hill Kurseong subdivision of Darjeeling District of West Bengal in
India. Mirik is surrounded by some of the best tea
gardens of this region. The climate of Mirik is
generally pleasant for most part of the year. It is a
tourists’ resort. The lake has a maximum depth,
minimum depth and water spread area of 26 ft,
6 ft and 0.1618 km
2 , respectively. The lake is fed
by both perennial streams and rainwater. The
catchment area includes human habitations.
The Mirik Lake is situated in a natural topographic depression or valley encircled by hill
ridges with hills gradually rising on southern
and southwestern parts and with extensive
natural drainage network. The hill slopes are
mostly covered with pine trees, while Darjeeling
gneiss is exposed on hill top. As such, the lake
receives waste water from human settlements
through numerous inlets. A small outlet discharges the spillover water of the lake into the
River Mechi.
The lake ecosystem acts as a natural sink for
removal of pollutants from the surrounding environment. This lake has been included under
National Lake Conservation Programme of
MOEF, GOI. Thirty-three genera of algae were
recorded from the Mirik Lake. Out of these, 13
belonged
to
Chlorophyceae,
12
to
Bacillariophyceae, 6 to Cyanophyceae and one to
Euglenophyceae. Some of the plankton are
Chlamydomonas,
Scenedesmus,
Chlorella,
Ankistrodesmus,
Closterium,
Spirogyra,
Pediastrum,
Ulothrix,
Chlorococcum,
Cosmarium , Navicula, Synedra, Melosira,
Gomphonema,
Cyclotella,
Fragilaria,
Pinnularia,
Oscillatoria,
Phormidium,
Anabaena, Spirulina, Euglena, etc. The genera
like Euglena, Oscillatoria, Scanadesmus,
Anacystis and Navicula were found generally in
organically polluted waters (Palmer 1969).
Thirty-three genera of algae were detected in
different sites of Mirik Lake, but only ten of
these (fi ve from Chlorophyceae, three from
Bacillariophyceae and two from Cyanophyceae)
algal genera fulfi lled the criteria of Palmer (1969)
as pollution indicator. However, Ankistrodesmus,
Chlorella, Closterium, Scenedesmus , Gomphonema,
Melosira, Navicula , etc., were found to be the
most pollution-tolerant genera of Mirik Lake
throughout the year. According to Palmer
(1969), a total score of 20 or more for a sample
is an indicator of organic pollution. Further,
forms like Oscillatoria and Spirulina are
believed to be indicators of heavy pollution.
And these have been recorded in the Mirik
Lake. Further, Spirogyra is sometimes believed
to be biological indicators of contaminated
waters. The presence of Spirogyra in the Mirik
Lake is an indication of high organic pollution
in Mirik Lake.
20 Wetlands of India
20,000 families, including fi shermen, paddy cultivators and vegetable growers, living on the outskirts of Calcutta City, depend on these wetlands
for their livelihood. These wetlands are highly
effi cient oxidation waterbodies for treatment of
domestic sewage.
Threats
Reclamation of a large portion of the wetland
(measuring about 5,000 ha), for agriculture and
urbanisation, is a major threat from real estate
interests.
Conservation
Some of the conservation initiatives and measures are as follows: (a) Proclamation of an
injunction by the Hon’ble Calcutta High Court
(HC) on the basis of a writ petition fi led by an
NGO named ‘People United for Better Living in
Calcutta (PUBLIC)’ restraining the state government from any further reclamation of any portion
of the wetland for commercial and recreational
purposes. (b) All the wetlands of East Calcutta be
declared as being of national signifi cance and be
brought under protection. However, they were
later designated as Ramsar wetlands on 19
August 2002.
20.3.23.5 Mirik Lake in Darjeeling
Himalayas
Mirik Lake (also called the Sumendu Lake),
lying at 1,767 m MSL, between 26° 54′ N and
83° 13′ E, is an artifi cial reservoir of Mirik town,
which was constructed in 1979, under ‘Mirik
Tourist Project’, primarily for the facilitation of
commercial tourism in Darjeeling. The lake is
situated in Mirik area in the hill Kurseong subdivision of Darjeeling District of West Bengal in
India. Mirik is surrounded by some of the best tea
gardens of this region. The climate of Mirik is
generally pleasant for most part of the year. It is a
tourists’ resort. The lake has a maximum depth,
minimum depth and water spread area of 26 ft,
6 ft and 0.1618 km
2 , respectively. The lake is fed
by both perennial streams and rainwater. The
catchment area includes human habitations.
The Mirik Lake is situated in a natural topographic depression or valley encircled by hill
ridges with hills gradually rising on southern
and southwestern parts and with extensive
natural drainage network. The hill slopes are
mostly covered with pine trees, while Darjeeling
gneiss is exposed on hill top. As such, the lake
receives waste water from human settlements
through numerous inlets. A small outlet discharges the spillover water of the lake into the
River Mechi.
The lake ecosystem acts as a natural sink for
removal of pollutants from the surrounding environment. This lake has been included under
National Lake Conservation Programme of
MOEF, GOI. Thirty-three genera of algae were
recorded from the Mirik Lake. Out of these, 13
belonged
to
Chlorophyceae,
12
to
Bacillariophyceae, 6 to Cyanophyceae and one to
Euglenophyceae. Some of the plankton are
Chlamydomonas,
Scenedesmus,
Chlorella,
Ankistrodesmus,
Closterium,
Spirogyra,
Pediastrum,
Ulothrix,
Chlorococcum,
Cosmarium , Navicula, Synedra, Melosira,
Gomphonema,
Cyclotella,
Fragilaria,
Pinnularia,
Oscillatoria,
Phormidium,
Anabaena, Spirulina, Euglena, etc. The genera
like Euglena, Oscillatoria, Scanadesmus,
Anacystis and Navicula were found generally in
organically polluted waters (Palmer 1969).
Thirty-three genera of algae were detected in
different sites of Mirik Lake, but only ten of
these (fi ve from Chlorophyceae, three from
Bacillariophyceae and two from Cyanophyceae)
algal genera fulfi lled the criteria of Palmer (1969)
as pollution indicator. However, Ankistrodesmus,
Chlorella, Closterium, Scenedesmus , Gomphonema,
Melosira, Navicula , etc., were found to be the
most pollution-tolerant genera of Mirik Lake
throughout the year. According to Palmer
(1969), a total score of 20 or more for a sample
is an indicator of organic pollution. Further,
forms like Oscillatoria and Spirulina are
believed to be indicators of heavy pollution.
And these have been recorded in the Mirik
Lake. Further, Spirogyra is sometimes believed
to be biological indicators of contaminated
waters. The presence of Spirogyra in the Mirik
Lake is an indication of high organic pollution
in Mirik Lake.
20 Wetlands of India