Sambar lake migratory bird epidemic: Facts and Reason

Last few day, Disturbing reports of 25000 Birds dying at Sambar Lake flooded the Social media.

The death on migratory birds is not a new phenomenon and in most cases it is caused by Avian Influenza Virus (Bird flu). It happens every other year but usually the number of birds dying is in low hundreds.

Most of us get to hear about the Bird flu, only when our favourite bird (Tandoori Chicken) gets affected.

The eerie feeling (when you know something wrong is happening) started creeping in me.

Bahar Dutt Report from ground Zero opened up a new angle.
She blamed the salinity of the lake caused by illegal salt mining for the Bird death.

Most of the Print media is simply recycled her reports and failed to explore or provide deeper insight into this issue.

I don’t think we can pin point a single reason for such a catastrophe. Multiple factors need to come together to cause such a catastrophic event.

Probable reasons could be:

• Salinity (Not sure how it would have direct impact on bird health)
• Poisoning (deliberate or Toxic waste bump)
• Avian Influenza (Virus) or other virus
• Botulism (Bacteria type) or other Bacteria

My views:

• Salinity
Sambar is a natural Salt lake and its salinity changes with season. Salinity peaks in the summer season (because of excessive evaporation) and is lowest, post monsoon. Salinity less than 40mg per litre is considered normal.

Was 40mg per litre level breached?

Assuming it was breached, then why didn’t Hindustan Salt limited stop their salt production?
There has to be a mechanism where in HSL is held responsible to maintain salinity of the lake.

Illegal salt mining:

Though we can’t ignore this factor but were they responsible for the salinity?
They pump-out water thorough bore wells and not directly from the lake.
There shouldn’t be any impact on the water level or the salinity of the lake because of them. Only if they are draining the leftover brine in the lake then there might be some impact.

Pumping out water from the ground could affect the Aquifer level.
Has the aquifer level dropped drastically?
What is its impact on the lake water level?

Unless we know the Shape, Size, Depth of the Aquifer and Shape, Size and Location of its catchment area, I am not sure if we can comment on the impact.

Effect of Salinity on the Ecosystem

Migratory birds which visit Sambar Lake mostly live around the sea. These birds know how to regulate the salt in their body. Birds are smart and they will move to another location if the condition of a water body is adverse. Why would they stay here to die?

Most Crustaceans and other micro-organism will not survive if the water gets over saline. As the food supply depletes, Birds would move to other locations.

Poisoning (Deliberately by Farmers or Toxic waste Dump)

Most birds which visit Sambar feed in the lake and their impact on the farmed crops is minimal. Chances of they being poisoned by framers is not there.

A lot of industries have mushroomed around the lake.
Sambar is no longer a sleepy town but is a developing “C” Grade City. Toxic dump is a possibility but initial water test reports have ruled it out.

Avian Influenza (Virus) or other virus

Initially it was suspected to be the cause but Lab in Bhopal has ruled it out. It’s a good new that it’s not Bird Flu but the lab failed to provide answers to what was causing the deaths

Botulism (Bacteria type) or other Bacteria

Botulism seems to be the most viable reason at this moment. Strangely none of the officials has come forward to confirm this.
Testing for Botulism is not that difficult but why has it take more than 15 days for the Govt. Lab to confirm?

• How and from where did these Bacteria come?
• Why did they multiply so much?
• Was this purely natural phenomenon or are we humans responsible?

Botulism Bacteria is present in the wild. It doesn’t matter if an infected bird brought it to Sambar or if they contracted these bacteria here.

What matter is: Why did this bacteria multiply and infect at such rapid pace?

The Factors which influence the Botulism bacterial growth
• High salinity
• High Temperature (25-40 degree)
• Anaerobic Conditions

These factors are not under our control, at least not is a short term control.
What else could be influencing the bacterial growth?


Reasons for high BOD could be
• Temperature
We can’t control the Temperature, so no point discussing it, unless there has been few exceptional hot days and we want to link this with Global warming.

• Release of untreated sewage
Successive Govt have worked hard developed this sleepy town. Builder’s have bought, developed and sold land around the lake. Such unplanned colonies, mushrooming urban villages lack the basic facilities of sewage water treatment.
So where does the sewage go, if not in lake?

Unlike lakes in the hills, which have a natural drainage system, Sambar Lake doesn’t. Sewage build-up at Sambar Lake was bound to happen.

• Increase levels of in Nitrogen and Potassium in water.
Drastic change in the agricultural practices in happening in Rajasthan. Excessive use of fertilizers and pesticides is a norm.
Runoff water from the farm can also cause a spike in Nitrogen and Potassium.(basic components of most fertilizers)

Drop in water level, increase in water temperature,increase in Salinity, clubbed with high BOD and high Nitrogen and Potassium could be the reason of the growth of Botulism Bacteria

Some Basic Facts
• The lake has shrunk from 190 km to 30 km.
The catchment area of the lake developed and the natural flow of water restricted.
The hydrological Cycle disturbed.
Low water levels means water temperature will shoot up on a hot day
• Major development has happened in the areas exposed but shrinking of the lake
• Unplanned development of the City and the urban villages
• Lack of Basic facilities like Sewage treatment plant.
• Change in the local agricultural practices

Who to Blame?

• Govt of Rajasthan:

  1. For almost a decade, Red flags have been raised but nothing much has been done for the lake.
  2. They are in contempt of the Supreme Court ruling which made states responsible for all wetlands and their catchment area.
  3. Not implementing the Inland Wetland management rules 2010 and 2016
  4. For not providing proper representation in Wetland management authority and for failure to oversee it’s functioning.
  5. Allowing encroachment of the lake bed and Development of lake bed


  1. For their failure to protect the wetlands and in their failure in highlighting this issue.
  2. Not implementing the Inland Wetland management rules 2010 and 2016

• HSL (Hindustan Salt Limited):
They were the custodian of the lake.

  1. They gave a blind eye on the encroachment happening.
  2. They failed to check illegal salt mining and Water extraction.
  3. They allowed untreated sewage and farm runoff to contaminate the lake.

• Forest Dept:
Though the lake management isn’t under them but they are responsible for the ecosystem that existed there.

• SLDA (Sambar Lake Development Authority):
They we constituted to revive the lake. They have done nothing to this effect.

  1. Instead of reviving the lake they have been trying to develop the lake into a tourist spot.
  2. For planning Cycling track, Train ride, Boat rides and hotels on the lake

• Local DM and SDM:
For their failure to check encroachment of the lake and for letting the illegal mining of salt.

Not sure who is to be blamed to the untreated sewage which is finding its way to the lake.

What can/ What should be Done?

• Operation of HSL to be stopped till the revival of the lake is complete
• Implementation of Inland Wetland management rules 2016
• Steps to be taken to make sure that the natural flow of water to the lake is re-established. This step will include removal of encroachment from the lake and its catchment area
• Feasibility study to find alternate source of water for the revival of lake
• Steps need to be taken to prevent untreated sewage water from entering the lake.
• Setting up of Sewage treatment plants
• The lake to be transferred to the forest Dept for maintenance and protection
• Prevent surface runoff from the farm
• To halt all lake side development till a healthy eco system is developed

-Pankaj Gupta is a Delhi based Birder. And regional reviewer for eBird – a citizen science project by Cornell Lab USA. He has been birding for the last 12 years.