Uncovering Hidden Pollution in Arkavathi River 

What we routinely measure in a river shapes what we understand about its health. But what happens when we look beyond the usual water quality parameters?

In February and March 2024, Paani Earth Foundation, in collaboration with the International Centre for Clean Water (IIT Chennai), tested water and sediment at seven locations along the Arkavathi and Vrishabhavathi rivers.

We looked beyond routine indicators of river pollution, testing for 65 parameters in water and 20 in sediment, including pesticides, heavy metals and hazardous organic compounds.

What did we find?

Pollution was not limited to what could be seen on the surface.

Every location we tested had pollutants exceeding one or more Indian or international standards and guidelines. Pesticides, heavy metals and hazardous organic compounds were detected across the river system, including at locations where there were few visible signs of pollution.

The findings also pointed to the influence of urban wastewater and industrial activity, with changes in pollutant levels observed downstream of Bengaluru, industrial areas and other potential sources.

Explore the findings

Where were these pollutants found? How did concentrations change as we moved downstream? And what does the river look like when we examine pollution beyond the parameters routinely monitored?

Dive into the detailed report sharing the findings from the March-April 2024 study

Interactive map to explore the findings from the study with a spatial context. 

What needs to change?

 

Monitor what matters.

Expand monitoring beyond conventional parameters to include emerging and hazardous contaminants where there is evidence of risk.

 

Find and stop pollution at source.

Use monitoring and spatial evidence to identify where pollutants are entering the river and strengthen action on sewage, industrial effluent and other sources.

 

Make monitoring more representative and transparent 

A river changes through the day, across seasons and as different discharges enter it. Understanding its condition from a single water sample collected once a month can therefore provide only a snapshot of what is happening at that place and time.

When only a limited set of basic parameters from that monitoring is easily available in the public domain, the picture becomes narrower still. Pollutants that are not routinely tested for or reported, changes during the day, and short-lived pollution events can remain invisible.

If monitoring is to guide river restoration, we need data that better represents these changes, looks beyond basic parameters where the risks warrant it and makes the underlying data and trends accessible in the public domain.

Water-quality data, including raw monitoring data and trends over time, should be easily accessible so that river restoration can be assessed against evidence.

Restoring the Arkavathi is not only about cleaning a polluted river. It is about protecting a local water system that Bengaluru once depended on — and could have a role in its water future.  

Explore Arkavathi River Basin

 

Back to Exploring the State of Cauvery River Basin

A closer look at how the Arkavathi is monitored

In 2025, we took a closer look at the National Water Quality Monitoring Programme and the CPCB Water Quality Monitoring Guidelines (2017) to understand how river water quality is monitored, what is made available in the public domain, and where the gaps remain.

A river changes through the day, across seasons and as different discharges enter it. A single sample collected once a month can therefore provide only a snapshot. When only a limited set of basic parameters from that monitoring is easily available in the public domain, the picture becomes narrower still.

We looked at these gaps in more detail and what they could mean for understanding the state of the Arkavathi.

Read our NWMP analysis here.

We had also submitted a representation with the analysis findings to Central Pollution Control Board and Karnataka State Pollution Control Board on January 24th, 2025.