What do we know?
Over the years, government agencies, courts, scientific institutions and the media have documented a range of environmental challenges affecting the Cauvery Basin. The facts below highlight some of the key issues identified through these sources. They are intended as a starting point for understanding the basin’s current state and will be expanded as additional evidence becomes available.
Image by Bishnu Sarangi from Pixabay
Key Fact # 1: Diminishing Natural Vegetation Cover
45.55% of natural vegetation in the Cauvery Basin was lost between 1965 and 2016
Why does diminishing natural vegetation matter?
Natural vegetation helps sustain river flows, recharge groundwater, prevent soil erosion, support biodiversity and improve climate resilience. Its loss can have far-reaching impacts on the basin’s water security and ecological health.
What action has been taken?
NGT (Southern Zone) initiated proceedings in March 2024 after taking cognizance of the reported green cover loss and directed the concerned states to respond. The NGT’s Southern Zone Bench has been monitoring the matter since March 2024. Following repeated non-compliance by the respondent states, the Tribunal has issued a final direction to Karnataka, Tamil Nadu and Kerala to file their reports, stating that it may proceed suo motu if they fail to respond (Source: Deccan Herald Article June 20th, 2026)
Last Updated: July 30th, 2026
Polluted flows from Hassan into Yagachi River December 2025.
Key Fact # 2: Unabated pollution
Several stretches of the Cauvery Basin continue to be identified as Polluted River Stretches, while scientific studies have detected contaminants including heavy metals, pesticides, pharmaceuticals and other emerging pollutants in parts of the basin.
Why it matters?
River pollution threatens aquatic ecosystems, biodiversity, drinking water sources, agriculture and public health, while reducing the river’s ability to sustain healthy ecosystems.
What action has been taken?
In its landmark judgment in Paryavaran Suraksha Samiti vs Union of India [(2017) 5 SCC 326], the Supreme Court converted long-standing statutory obligations for treating industrial effluents and municipal sewage into enforceable nationwide directions. The Court mandated the establishment and operation of ETPs, CETPs and STPs within prescribed timelines and entrusted the National Green Tribunal with monitoring compliance. This oversight has since continued through a series of NGT proceedings, including OA No. 593/2017 (sewage and industrial effluents) and OA No. 673/2018 (polluted river stretches). The monthly progress reports are submitted to the Central Monitoring Committee under Ministry of Jal Shakti and can be found here.
News Article about the Cauvery River Running Dry : TOI June 2026
Key Fact # 3: Water Scarcity
The Cauvery Basin is classified as a water-scarce basin under the Falkenmark Water Stress Indicator, meaning that the annual renewable freshwater available is insufficient to sustainably meet the growing demands of people, agriculture, industry, and ecosystems. Climate studies further project that the basin is likely to continue drying until 2050, even as some other major Indian river basins are expected to become wetter.
Why it matters?
The Cauvery Basin has limited renewable freshwater to meet the needs of people, agriculture, industry, and ecosystems. Population growth, urbanisation, industrial development, and water-intensive agriculture continue to increase pressure on these finite water resources. As India pursues green policies such as higher ethanol blending targets, greater cultivation of water-intensive crops like sugarcane could further increase water demand in already water-scarce regions. This underscores the need to align water, agricultural, energy, and land-use policies to ensure long-term water security.
What action has been taken?
Karnataka Government is responding through initiatives such as demand management, new reservoirs to capture rainwater, river diversion projects such as the Yettinahole project, groundwater regulation, treated wastewater reuse, rainwater harvesting, micro-irrigation, and lift irrigation projects. Many of these efforts are supported by policies, regulatory frameworks, and directions issued by the National Green Tribunal and the courts. Evaluating how effectively these initiatives are being implemented and whether they are improving long-term water security remains essential.
Illustrative map showing some of the dams, weirs, and anicuts that fragment the Cauvery River between the Krishna Raja Sagara (KRS) Dam and Shivanasamudra. This is not an exhaustive representation.
Key Fact # 4: Fragmented River and threatened biodiversity
Extensive damming has fragmented the Cauvery River, altering its natural flow, degrading water quality, disrupting sediment transport, and contributing to the decline of freshwater ecosystems and migratory fish species.
Why it matters?
Healthy rivers depend on rich biodiversity. The loss of native species weakens ecosystem resilience, disrupts food webs, reduces fisheries, diminishes the benefits that rivers provide to people and can increase human-wildlife conflicts as habitats become fragmented and degraded. River fragmentation along with pollution and other human pressures are contributing to the decline of freshwater biodiversity in the Cauvery Basin with endemic species such as the mahseer among those most affected.
Data Sources
Some studies that directly correlate fragmentation to the biodiversity issues.
1.Dam Induced Hydrological Alterations in the Upper Cauvery Basin, 2022 Study
2. Fisheries as ecosystem services: A case study of the Cauvery river basin, India
3. Hindu Article reporting the endangered status of the Hump Backed Mahseer endemic to Cauvery
What action has been taken?
Fish sanctuaries and other conservation measures offer protection to freshwater biodiversity in parts of the Cauvery River System.
At the same time, new water infrastructure and projects that seek to store, divert or extract more water from the Cauvery continue to be proposed like the Mekedatu Dam Project. These can add to the fragmentation of an already heavily regulated river system and cause irreversible damage to the ecology of the already stressed river.
This leaves an important question: are we looking at the cumulative impact of existing and proposed projects on the river as one connected system?
