The present rate of sedimentation in the Rewalsar Lake, 3.92 cm/year, was still much higher than that of the other north-western Himalayan lakes which is less than 1 cm/year

MANDI– Rewalsar Lake in Mandi district of Himachal Pradesh, India, has come into lime-light for mass death of thousands of fish in just two days. News reports even suggested that 90 percent of fish in Rewalsar are now dead. Before fish started dying, the color of the water suddenly turned muddy on April 18, 2017. For next two days, fishes continued to die. From usual green, the color changed to muddy. Leela Vashishth, a resident of Rewalsar, lodged a complaint with Balh police station on April 19 on suspicion that some unidentified person could have contaminated the lake water with chemical or other sort of poison to kill the fish. A case of mischief by killing animals has been registered.  It’s indeed a wise thing to consider this possibility as well. However, mass death of fish isn’t a surprise, and the lake doesn’t require someone to poison it to kill aquatic life. It’s already dying.

The lake has eventually reached on the verge of dying due to pollution, sewage discharge, rainwater flooding, sedimentation, siltation, excess growth of weeds, and mess created by visitors. Slumber of the administration is again apparent.

Located at 1360 meters above sea level, Rewalsar, also known as Tso Pema to Buddhists, is one of the most unique places in Himachal that possesses a diverse and rich history. The lake is of great spiritual and religious importance to three religious communities, Sikh, Budhisht, and Hindus. There are monasteries, a gurudwara, temples of Lord Shiva and Lord Krishna, and saint Lomas. This pristine lake is formed in the hollow of the mountains and the history dates back to the times of Budhisht Guru Rinphoche. There is a wonderful story associated with the formation of the lake. It used to be an amazing place. But now, the pollution and siltation is killing it.

The degrading condition of the lake was aptly brought to the attention of the district administration and authorities responsible for conservation and protection of the lake since last seven to eight years. It was not the first time that fishes have died in the lake.

Thousands of fish had died in the Rewalsar lake in July 2014 too. The authorities had cited flooding of rainwater into lake as the reason for death of fish. Excess dispersal of feed to fish by pilgrims and tourist was another major reason, which continued despite demand of ban on this practice.

After this incident, the Pradhan of the Nagar Panchayat, Bansi Lal Thakur, had told a Hindi Daily that the Chief Minister had laid foundation stone for establishment of sewerage system on May 11, 2012. The CM had allotted budged to the Irrigation & Public Health Department, and had asked to complete the work as soon as possible. Sadly, the small township settled on the boundary of the square-shaped lake still lack sewerage system. He had also said that DPR was prepared to remove silt, but the department hadn’t move a muscle in reality.

A report had appeared in 2015 in which it was revealed that the lake is overcrowded as there is no control on population growth of fish. The area of the lake is ideally suitable for presence of not more than 15, 000 fish. However, the number of the fishes were in lakhs. The administration tried to shift thousands of fish in other water-bodies and rivers but didn’t succeed in solving the problem. The report had also pointed out that the township lacks proper drainage system and all domestic wastewater and rainwater ends up in the sacred lake. The catchment slope of the lake is such that all rainwater flows right into it.

In May 2016, again thousands of fish were choked to death due to rise in water toxicity level. The administration stood helpless and did nothing more than burying the the dead fish. Administration didn’t bothered about this grieve crisis the lake had been facing.

Rewalsar Development Action Group, an NGO, raised the demand to take measures to prevent pollution of the lake. The NGO had also submitted a special report on conservation of the lake to the government. Save Rewalsar Lake campaign was also launched.

In April 2016, the National Green Tribunal has ordered ban on use of plastic around the lake, which was hardly followed. The NGT had pointed out complete failure of government to protect the lake. The tribunal had constituted a four-member high-level committee comprising of Secretary, HP Pollution Control Board the Secretary, Environment, and Secretary, Irrigation and Public Health. The committee was supposed to submit a comprehensive report over possible solutions for the restoration of original condition of the lake. God knows what happened to that report and the committee.

In June 2016, the issue of alarming degradation of the lake was again raised by the locals and the NGO. The community was still pleading for sewerage system and measures to prevent flood-water and domestic waste-water from draining into the lake. When an engineer of the Pollution Control Board, RK Nadda, was asked about the matter, he had simply refused to comment. District administration had told media that it’s seeking funds from the government. Again, there were only problems but no solution.

In March 2017, the Rewalsar Development Action Group approached the Chief Secretary, VC Pharka and the Deputy Speaker, Jagat Singh Negi requesting intervention to save the lake. President and Secretary of the Group briefed them about the plight of the lake and need to remove rising siltation. They again pleaded for the sewerage system. 

A research study by the Wadia Institute of Himalayan Geology (WIHG), Dehradun and Physical Research Laboratory, Ahmedabad tittles “Rapid sedimentation history of Rewalsar Lake, Lesser Himalaya, India during the last fifty years…”

The study carried out using Pb and Cs dating on the top 2 meter (below lake floor) core of the lake. They found an average sedimentation rate of 3.35 cm/year during the last 50 years which is found to be the highest in comparison to the other lakes in the north-western Himalayan region.

The study concludes,

“During 1995 to 1963 AD, the Rewalsar Lake experienced a rapid sedimentation rate of 3.92 cm/year while it reduced to 2.78 cm/year after 1995 AD. At the Rewalsar Lake, the natural parameters, such as lithology, catchment area and slope, rainfall, etc. do not appear to be the limiting factors controlling the rate of sedimentation.”

The study further added,

“Rather, human interference, in terms of civil constructions and growth of township in the lake catchment area appears to be the most plausible factor controlling the sedimentation rate during the past fifty years.”

Comparison of Rewalsar Lake and some of the north-western Himalayan lakes

The study also said that,

“The present rate of sedimentation in the Rewalsar Lake, 3.92 cm/year, was still much higher than that of the other north-western Himalayan lakes which is less than 1 cm/year.”

“An early action plan is required to be followed up by the concerned authority to arrest the extremely higher sedimentation rate Rewalsar Lake and to protect the water body from faster degradation,” further suggested the study.

As we know, on April 17, locals were shocked to see sudden change in the color of the lake water. It turned muddy and suggested possible contamination. In next two days, thousands of fish were seen struggling to breath as soluble oxygen levels dropped to critical 0.8%. Aquatic life requires minimum level of 4-15 mg/L to support aquatic life (Fish). Thousands of fish died in next couple of days. The administration had to collect the dead fish and dispose of them to prevent health hazard.

Nearly, 5000 fish were rescued by shifting to other water bodies, claimed the administration. For media, the reason for mass death of the fish was low-level of oxygen. However, no one commented about the reason behind depletion of oxygen levels. Now, a ban has been imposed on feeding the fish and shopkeepers are directed not to sell fish-feed. Public is prohibited to visit the lake due to health hazards.

The government has again formed a committee to examine the issue of possible adverse effects on the natural aquifer and assess the chances of possible contamination of water. Committee is supposed to submit a report regarding the whole situation in detail, pinpoint reasons for fish mortality and suggest remedial measures.

The committee will be headed by Divisional Forest Officer, Mandi and Environment Engineer, HPSPCB, Bilaspur, Assistant Director, Fisheries, Mandi will be is members while Shri Kamraja Kaisth, Principal Scientific Officer-I, State Council for Science, Technology and Environment as its Member Secretary.

Additional Chief Secretary Environment, Science and Technology Shri Tarun Kapoor said the committee will assess and will submit its report to the Government within seven days.