
Sindh’s Thar Desert is characterized by arid and semi-arid conditions, making water scarcity a significant challenge for the communities living in the region. The desert has few natural surface water sources such as rivers or lakes. The scarcity of these water bodies restricts the availability of water for both agricultural and domestic purposes. The region also experiences erratic and low rainfall, making it highly dependent on monsoons. The infrequent and unpredictable nature of rainfall, too, leads to insufficient water availability for crops and other needs. The growing population here puts additional stress on the available water resources. Increased demand for water for agriculture, livestock, and domestic use intensifies the scarcity issue. The Thar Desert, like many other arid regions, is similarly susceptible to the impacts of climate change. Changes in temperature, precipitation patterns, and extreme weather events, therefore, can further exacerbate its water scarcity issues.
Within this backdrop, recently excavated large-scale lignite mines place new stresses on the availability of clean water in the Thar Desert.
Lignite is a type of coal characterized by its low carbon content and high moisture content. It is usually extracted from open-pit mines which require dewatering so as to lower the water table in them and create a dry working environment. This process, however, can lead to the generation of the contaminated wastewater due to various factors. For instance, as water infiltrates lignite deposits in the mine pit, it comes into contact with minerals, rocks, and other solids present in the mining area. This contact can result in the leaching of minerals and contaminants from the surrounding geology into the water, leading to elevated levels of dissolved and suspended solids. Lignite itself contains various organic compounds and can undergo decomposition when exposed to air and water. This decomposition process can release soluble organic substances, humic acids, and other byproducts into the water, contributing to the contamination. Pyrite, a common mineral found in lignite deposits, can oxidize when exposed to air and water. This process leads to the formation of acidic drainage, which can contain sulfate ions, heavy metals, and other contaminants.
Acid mine drainage, in fact, is a significant concern in coal mining as it can contribute to the contamination of the wastewater produced during pit dewatering. Mining operations also often use chemicals for various purposes, such as dust suppression, ore processing, or flotation. These chemicals can also be introduced into water during mining and processing activities, contributing to the overall contamination of wastewater. Surface runoff from the mining areas, including areas where coal is stockpiled or processed, can pick up pollutants and contaminants too and can carry them into the pit dewatering system. This runoff can include sediments, heavy metals, and other pollutants. Lastly, mining equipment and infrastructure can corrode over time due to exposure to water and various minerals. This corrosion can release metals and other substances into the wastewater produced during dewatering, further contributing to its contamination.
Water from 27 pumps at the coal mine in Thar
As early as 2010, scientists predicted that lignite mining in the Thar Desert would generate large quantities of mine water requiring treatment. Other scientists have identified lignite fields in the Thar Desert as potential sources of arsenic and mercury contamination of groundwater. Google Earth satellite images clearly show the accumulation of mine water within the mine pits of Thar Coalfield Block I and Thar Coalfield Block II. Environmental and Social Impact Assessments (ESIAs) for these two blocks suggest that companies involved in lignite mining there are treating mine water using reverse osmosis (RO) water treatment plants. This process raises an important question: What is the ultimate fate of the rejects from the RO water treatment plants since these rejects contain contaminants derived from the open pits of these lignite mines?
Within this context, I interpreted water quality data of groundwater samples collected on 28 June 2022 from Sinjhara, a village in Tharparkar district. These samples were originally analyzed by the Mehran University of Engineering and Technology, Jamshoro, for the Alliance for Climate Justice and Clean Energy (ACJCE).
I found that all of the drinking water samples collected are unfit for human consumption because of elevated levels of toxic metals (selenium, arsenic, mercury, chromium, and lead) in them. Below I am specifying the problems found in each sample:
- Water taken from Khario Ghulam Shah’s village well (located in a locality called Aban Jo Tar) contains unsafe levels of mercury and lead that exceed Sindh’s provincial standards for drinking water quality;
- Water taken from the Jamun Samo’s village well contains unsafe levels of mercury and lead that exceed Sindh’s provincial standards for drinking water quality, and a level of arsenic that exceeds World Health Organization’s drinking water quality guideline value;
- Water taken from Bhittra village’s Amra well contains unsafe levels of selenium, mercury and lead that exceed Sindh’s provincial standards for drinking water quality, and a level of arsenic that exceeds the World Health Organization’s drinking water quality guideline value;
- Water taken from a water tank located in Paro Jo Tar locality contains unsafe levels of selenium and mercury that exceed Sindh’s provincial standards for drinking water quality; it also has levels of arsenic and lead that exceeds the World Health Organization’s drinking water quality guideline value; and
- Water taken from a water tank in Meghe Jo Tar locality contains unsafe levels of selenium, mercury, chromium and lead that exceed Sindh’s provincial standards for drinking water quality; it also has levels of arsenic and lead that exceeds the World Health Organization’s drinking water quality guideline value.
Although drinking water quality standards do not apply to the sample taken from the water pipeline in Meghe Jo Tar, the levels of toxic contaminants found in this sample are higher than those found in other samples. For instance:
- Selenium level in this sample is 0.20 milligram/liter compared to the next highest selenium level of 0.072 milligram/liter found in Meghe Jo Tar’s water tank;
- Arsenic level in this sample is 0.09 milligram/liter compared to the next highest arsenic level of 0.026 milligram/liter found in Jamun Samo’s village well;
- Lead level in this sample is 0.33 milligram/liter compared to the next highest lead level of 0.15 milligram/liter found in Meghe Jo Tar’s water tank;
- The mercury level in this sample is 0.095 milligram/liter, the second highest mercury level found in all the samples.
To the extent that water in Meghe Jo Tar pipeline has a hydrological connection to groundwater, this implicates it as a source of selenium, arsenic, mercury and lead contamination of the regional aquifer. By this same logic, wastewater being elwased in Jamun Samo does not appear to be a source of selenium, arsenic, mercury and lead contamination of the regional aquifer because of the relatively low levels of these substances in all the three samples taken from this wastewater.

Finally, levels of selenium, arsenic, mercury, chromium and lead in the nine water samples collected from in or near Thar Coalfield Block II on 28 June 2022 can be compared to levels of these toxic metals found in groundwater samples included in baseline surveys in the ESIA reports for Thar coalfield projects. The ESIA for the 330 megawatt coal-fired power plant in Thar Coalfield Block II dated 9 August 2016, for instance, contains baseline data showing the absence of detectable levels of selenium, mercury and chromium in those samples. The data also shows lead levels that ranged from 0.02 to 0.1 milligram/liter, and arsenic levels that ranged from 0.005 milligram/liter to 0.01 milligram/liter in the 40 wells whose water was analyzed. Similarly, the ESIA of two 330 megawatt coal-fired power plants in Thar Coalfield Block VI 2x dated March 2017 contains baseline data (at Table 78) showing the general absence, or very low levels, of selenium, arsenic, mercury, chromium and lead in the baseline surveys of groundwater
The baseline data, thus, suggests that excessive levels of these substances found in the nine water samples collected near Thar Coalfield Block II on 28 June 2022 are of recent origin and are associated with coal activities in the Thar. By this same logic, since the generally high levels of chloride and total dissolved substances (TDS) found in the baseline surveys of groundwater in the ESIA reports for Thar coalfield projects are generally similar to the levels of the same substances in the nine water samples collected on 28 June 2022, it is evidence that these levels are not of recent origin and may not be associated with coal activities in Thar Coalfield Blocks.
As the evidence given above suggests, the already existing water stress faced by the communities living in Thar has been exacerbated by the development of open pit lignite mines generating large volumes of contaminated water. So, in the light of the fact that the legal and judicial initiatives taken by these communities have been stalled, they need transparently provided answers from the government and corporate officials about the adverse impacts that might be occurring to their water resources due to the contaminants found in lignite mine water.

Dr. Mark Chernaik
Dr. Mark Chernaik is on ELAW’s Leadership Team and coordinates the Science Program, providing public interest advocates around the world comprehensive and timely scientific support in the pursuit of environmental justice. Mark joined ELAW in 1992 and focuses on helping partners challenge projects that would adversely impact public health or the Earth’s climate, often providing expert testimony. Mark received a doctorate in biochemistry from Johns Hopkins University and a bachelor’s in biochemistry from the University of Massachusetts at Amherst. He earned his law degree from the University of Oregon School of Law in May 1993.