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This article introduces Mapping Malnad’s updated Dakshina Pinakini River Basin Map, tracing the ~494 kms long interstate river from the Nandi Hills to the Bay of Bengal. The map brings together the river’s drainage network, lakes, dams, agricultural command areas, cities, industrial areas and monitoring stations, helping us see beyond Bengaluru’s perception of the river as merely a wastewater drain
Click here to load PDF version of the map
Dakshina Pinakini is known to us in Bengaluru as this large drain carrying black, foul-smelling, toxic wastewater from the eastern parts of the city. This includes wastewater that was diverted from entering the once-burning Bellandur Lake and now flows through the Varthur Lake diversion channel into the Dakshina Pinakini. Similarly, wastewater flowing into Yele Mallappa Shetty Lake eventually enters Dakshina Pinakini.
The fact that Dakshina Pinakini is a river is lost on us. Some, including the government, call it an “urban river”, a term that feels like a euphemism for a dead river.
The river is known by different names: Dakshina Pinakini in Karnataka and Thenpennai in Tamil Nadu. Thenpennai translates to South Pennar, a name that is also in use. The Central Water Commission (CWC) uses Ponnaiyar in its records, while Pennaiyar is another name for the river, used extensively in Supreme Court proceedings.
Originating on the eastern slopes of the Nandi Hills range at an altitude of about 1,000 m above mean sea level (MSL), the Dakshina Pinakini travels ~494 km before emptying into the Bay of Bengal. Its first ~87 km lie in Karnataka, followed by ~399 km in Tamil Nadu and another ~8 km in Puducherry.
Also read | Land Cover Map of the Dakshina Pinakini River Basin (ESA WorldCover 2021)
Why we made this map
Despite the Dakshina Pinakini flowing for about 494 km across Karnataka, Tamil Nadu & Puducherry, we found it surprisingly difficult to find a detailed basin map that allowed us to see the river in its entirety. This absence perhaps also contributes to how we perceive the Dakshina Pinakini in Bengaluru—as a drain carrying our wastewater rather than as a river that continues hundreds of kilometres downstream and empties into the Bay of Bengal. It is this gap that led us to prepare the Dakshina Pinakini River Basin Map.
We had previously made a Dakshina Pinakini map in 2022, under the banner of Paani.Earth, which gave us our first sense of the river basin as a whole. We have continued that work at Mapping Malnad, significantly updating the map to capture the river basin in much greater detail and with greater precision.
We make these detailed basin maps because they help us understand rivers. They allow us to see a river not merely as a channel flowing past a particular place, but as an interconnected system of streams, tributaries, lakes, dams, catchments, communities, cities and landscapes. Such a basin-wide view also enables systems thinking—helping us understand the connections, dependencies and consequences of interventions across the river basin.
What the map shows
The map brings together the Dakshina Pinakini catchment and its river and tributary network, lakes, dams and reservoirs, agricultural command areas, Central Water Commission (CWC) monitoring stations, and built-up areas across the basin. It also traces the direction of river flow from its headwaters to the Bay of Bengal.
The catchment, drainage network, water bodies, reservoirs and agricultural command areas have been mapped using India-WRIS data, while built-up areas are derived from ESA WorldCover 2021. The gross storage capacities of major dams are taken from the Central Water Commission’s National Register of Large Dams (NRLD). We have also mapped major cities and settlements, industrial areas (Whitefield, Jigani-Bommasandra, Attibele and SIPCOT), the river’s origin in the Nandi Hills range, and its course across Karnataka, Tamil Nadu and Puducherry to the Bay of Bengal.
Note: There are varying figures in government & court documents and media reports for both the length of the river and the size of its catchment. Based on our GIS measurements, the Dakshina Pinakini is approximately 494 km long, with a total catchment area of 15,164.43 sq km. Karnataka accounts for about 24% of the basin and Tamil Nadu about 75%, with small portions extending into Andhra Pradesh and Puducherry.
A River in Dispute
The Dakshina Pinakini like the Cauvery is the subject of both interstate water-sharing and interstate river-pollution disputes between Karnataka and Tamil Nadu.
Interstate Water Sharing Dispute: Tamil Nadu filed a case before the Supreme Court (SC), contending that several works undertaken by Karnataka, including the Yargola Dam project (marked on map) on the Markandeya River in the Dakshina Pinakini River Basin, would cause a “substantial reduction” in the water reaching Tamil Nadu, affecting its water requirements and the livelihoods of farmers in Krishnagiri, Dharmapuri, Thiruvannamalai, Villupuram and Cuddalore districts. In February 2026, the SC ordered the constitution of an Inter-State River Water Disputes Tribunal to adjudicate the water-sharing dispute
Interstate River-Pollution Dispute: The metropolitan city of Bengaluru and its surrounding areas, including Anekal, are the primary urban-industrial polluters of the Dakshina Pinakini. The river receives untreated and toxic household sewage, institutional sewage from schools, colleges, hospitals and offices, commercial wastewater from hotels, restaurants & other businesses, industrial effluents from factories, and solid waste from domestic, commercial and industrial sources. The interstate pollution of the Dakshina Pinakini has been the subject of several cases before the National Green Tribunal.
For those of us in Bengaluru, the Dakshina Pinakini can easily disappear from view once it carries the city’s wastewater beyond its boundaries. Mapping the entire basin brings the river back into view—not just as the polluted channel we see in Bengaluru, but as a 494-km interstate river connecting landscapes, communities and water uses all the way to the Bay of Bengal.
If you spot any errors or have suggestions for improving the map, please write to us at mappingmalnad@gmail.com
The Hindu | Video: Coverage of the Dakshina Pinakini, featuring Mapping Malnad’s Nirmala Gowda.
Dakshina Pinakini is yet another casualty of Bengaluru’s rapid and unmindful urban expansion, choked by sewage, industrial effluents and the staggering quantities of solid waste the city throws up every day.
The work below was produced under the Paani.Earth initiative, which the Editor of Mapping Malnad co-founded and curated until December 2024. Earlier work was undertaken through the Bangalore Environment Trust (BET). All of this work was pro bono and reflects the Editor’s work on the Dakshina Pinakini Basin prior to the launch of Mapping Malnad.
