MYSURU: The Cauvery river system, the lifeline of southern Karnataka, is facing a twin crisis that is becoming increasingly difficult to ignore. While pollution from untreated sewage, industrial effluents and unregulated tourism continues to degrade water quality, reservoirs that sustain millions of people are witnessing alarming drops in storage levels due to weak monsoon inflows and changing rainfall patterns.
The deterioration is evident in two of the river basin’s most important reservoirs, the Kabini dam in Mysuru district and Krishna Raja Sagar (KRS) dam in Mandya district. Together, they supply drinking water to Mysuru and Bengaluru, irrigate thousands of hectares of farmland and sustain rich biodiversity. But environmentalists warn that unless immediate corrective measures are taken, Karnataka could face serious challenges in ensuring clean water security in the years ahead.
Kabini backwaters becoming a dumping ground
One of the most worrying developments has emerged from the Kabini backwaters, a globally known eco-tourism destination bordering Nagarahole Tiger Reserve.
The Assistant Executive Engineer of the Kabini Dam has written to the Karnataka State Pollution Control Board (KSPCB) and police, seeking action against alleged dumping of waste by resorts, homestays, bars and hotels operating around the reservoir.
As per the letter dated June 20, a copy of which is available with TNIE, commercial establishments situated along the reservoir are allegedly disposing of solid waste and untreated liquid waste into the backwaters and surrounding areas without scientific treatment.
The authorities have sought inspections of tourism establishments to verify whether they possess functional waste management systems and sewage treatment facilities. They have also urged officials to initiate stringent legal action against violators.
Kabini backwaters are home to fish, reptiles, migratory birds and wildlife that depend on the reservoir ecosystem. Local communities also depend on boating, fishing and tourism for their livelihoods. Environmental experts warn that accumulation of plastics, food waste and sewage can alter water chemistry, reduce dissolved oxygen and damage aquatic biodiversity.
Though KSPCB regularly monitors river water quality through several stations across the Cauvery basin, environmentalists say that alone is not sufficient, unless it is backed by strict enforcement and timely corrective measures.
KRS also under pressure
The Krishna Raja Sagar reservoir, one of Karnataka’s most important water sources, faces similar concerns. Water quality is monitored at multiple locations, including KRS, Srirangapatna, Kushalnagar, Maddur, Mandya, KR Nagar and Hunsur.
Experts point out that pollutants entering the Cauvery upstream eventually accumulate within reservoirs where water remains stored for longer durations. Organic pollutants, nutrient loading and suspended solids affect reservoir ecology and increase treatment costs for drinking water utilities.
With KRS supplying drinking water to Mysuru, Mandya, Bengaluru and several towns, maintaining water quality has become as important as ensuring adequate storage.
Water levels witness worrying decline
Adding to pollution concerns is the sharp decline in reservoir levels this year. Both Kabini and KRS have recorded significantly lower storage compared to previous years due to delayed and deficient monsoon in their catchment areas.
Environmental scientists warn that lower storage volumes reduce the river’s natural ability to dilute pollutants. As water quantity decreases while sewage inflow remains constant, contaminant concentrations increase, affecting overall water quality.
Reduced inflows also result in stagnation, promoting algal blooms and bacterial growth, particularly where untreated sewage enters reservoirs.
The combination of shrinking water availability and rising pollution creates a dangerous cycle that threatens drinking water supplies, agriculture and ecosystems simultaneously.
Pollution’s hidden costs
The consequences of river pollution extend far beyond dirty water. Untreated sewage introduces harmful bacteria, viruses and parasites capable of causing diarrhoea, cholera, typhoid and other water-borne diseases.
Excess nutrients from sewage and agricultural runoff trigger eutrophication, leading to explosive growth of algae. As algae decompose, oxygen levels decline, killing fish and other aquatic organisms.
Industrial effluents often contain heavy metals and toxic chemicals that accumulate in sediments and aquatic organisms, entering the food chain over time.
Polluted reservoirs also increase operational costs for water treatment plants, forcing municipalities to spend more public money on purification before water becomes fit for consumption.
For farmers, poor water quality affects soil health and crop productivity over time, while tourism suffers when iconic destinations lose their ecological appeal.
Save Kabini Forum raises alarm
Advocate Ravi Kumar, spearheading the Save Kabini Forum, has repeatedly raised concerns over pollution in the Kabini river and backwaters. He said illegal discharge of untreated sewage and improper waste disposal by certain resorts and commercial establishments threaten both wildlife habitats and drinking water security.
He demanded a periodic inspection of resorts, mandatory installation and operation of sewage treatment plants, GPS-based monitoring of waste disposal and criminal prosecution of establishments found violating environmental norms.
He also called upon authorities to involve local communities in protecting the reservoir through regular vigilance and reporting mechanisms. “The Kabini reservoir is not merely a tourist destination; it is a drinking water source, a wildlife habitat and an ecological asset. Protecting it should become a collective responsibility of the government, local bodies and citizens,” he said.
What is the status of sewage treatment?
While Mysuru city has expanded its sewage treatment infrastructure over the years, environmentalists argue that treatment capacity and operational efficiency remain uneven across the basin. Many smaller towns continue to release partially treated or untreated sewage directly into streams that ultimately join the Cauvery system.
Similarly, numerous resorts and homestays located in rural areas either lack adequate sewage treatment facilities or fail to operate them consistently. Officials admit that even where sewage treatment plants (STPs) exist, maintenance, electricity shortages, poor monitoring and illegal bypass connections often reduce their effectiveness.
Experts believe that merely constructing STPs will not solve the problem unless treated water quality is continuously monitored and compliance strictly enforced.
Awareness remains equally important
Experts caution that enforcement alone cannot protect rivers unless citizens participate actively. Public awareness campaigns should encourage segregation of waste, discourage dumping into lakes and streams and promote responsible tourism.
Hotels and resorts must educate visitors regarding environmentally responsible practices, while schools can incorporate river conservation into environmental education programmes.
Religious organisations, farmer groups and local communities can play an important role in protecting riverbanks through periodic clean-up drives and monitoring illegal dumping. Citizen reporting through mobile applications and dedicated environmental helplines could also improve vigilance.
Kodagu’s ecological future linked to Cauvery
The Kodagu and Cauvery Protection Forum has urged the state government to accord special environmental protection to Kodagu, the birthplace of the Cauvery.
Forum Convenor, Col (Retd) CP Muthanna, described Kodagu as Karnataka’s “Green Gold Reserve” and demanded that the region be declared a Green Safety Corridor to prevent large-scale deforestation, indiscriminate construction and environmentally damaging development projects.
The Forum has opposed projects it believes could threaten Kodagu’s fragile ecology, including certain large housing developments and the proposed Mysore-Kushalnagar railway line.
It has also sought stricter regulation of illegal resorts and homestays, while advocating scientific limits on tourism.
Environmentalists agree that protecting forests in Kodagu is directly linked to safeguarding Cauvery’s long-term water security because healthy forests regulate rainfall, groundwater recharge and river flows.
Protecting Karnataka’s lifeline
The challenges confronting the Cauvery basin are no longer isolated environmental issues but matters of public health, economic security and climate resilience. The pollution of Kabini and KRS, shrinking reservoir levels, expanding tourism pressure and inadequate waste management together highlight the urgent need for integrated river basin management.
Experts believe that Karnataka must simultaneously strengthen sewage treatment, strictly enforce pollution control laws, regulate tourism in ecologically sensitive regions, restore forests in the upper catchments and encourage public participation in river conservation.
Without immediate intervention, the Cauvery’s declining health could compromise drinking water supplies, agriculture, biodiversity and livelihoods for millions who depend on Karnataka’s most important river system.