Grade E water bodies across the city are fuelling fears of dengue, chikungunya and malaria outbreaks
Several of the city’s lakes, once prized as ecological and recreational assets, have quietly turned into long-term mosquito breeding sites, according to public health officials who say the problem is getting far less attention than it deserves.
City authorities have largely focused their lake-related efforts on cosmetic upgrades and waterfront development. But physicians working with the Integrated Disease Surveillance Programme (IDSP) in Hyderabad say that’s missing the bigger picture: several of the city’s most polluted and hyacinth-choked lakes are now ideal habitats for mosquitoes that spread dengue, chikungunya and malaria.
What the survey found
The concern stems from findings in the 2026 Telangana Lake Health Survey, conducted by the Telangana Pollution Control Board (TGPCB). The survey found that many of Hyderabad’s prominent lakes — including Sunnam Cheruvu, Asanikunta and Uppal Cheruvu, along with a number of water bodies that had undergone recent restoration work — now fall under Grade E, the lowest rung of the state’s water-quality classification system.
Untreated sewage and industrial discharge flowing into these lakes has pushed dissolved oxygen levels down to between 0.3 and 1.1 mg/l, far below the 5 mg/l considered safe for a healthy aquatic ecosystem. At these levels, the water can no longer sustain fish or other aquatic life, effectively rendering the lakes biologically dead.
Why dead water breeds live mosquitoes
Paradoxically, water too degraded to support fish turns out to be excellent for mosquito larvae, which don’t face the usual predation that keeps their numbers in check. Compounding the problem, thick mats of water hyacinth — locally called Gurrappa Dekka — have spread across many of these lakes, further starving the water of oxygen while giving mosquito larvae a protective canopy.
That hyacinth cover does double duty for the insects: it shields larvae not just from natural predators but also from insecticide spraying carried out by the GHMC’s entomology wing, letting mosquito populations grow largely unchecked.
Entomologists who train GHMC field staff argue that this needs to be treated as a public health emergency rather than a matter of aesthetics or civic upkeep.
One senior IDSP doctor described the scale of the problem starkly, noting that mosquito swarms are readily visible near lakes such as Uppal Nalla Cheruvu in the evenings, and that residents living in dense neighborhoods next to these lakes are often unaware of the elevated health risk right outside their homes.
The lakes flagged as most affected
- Sunnam Cheruvu (Allwyn Colony/Kukatpally) — burdened by industrial runoff and untreated domestic sewage
- Asanikunta (Sainikpuri/Kapra) — contaminated inlet channels from nearby residential areas have left it severely oxygen-depleted
- Kamuni Cheruvu (Moosapet) — choked by dense hyacinth growth
- Fox Sagar/Kolla Cheruvu (Kompally/Jeedimetla) — affected by nearby industrial effluents and local sewage
- Rangadhamuni Cheruvu/IDPL Lake (Kukatpally) — near an industrial zone, showing heavy pollution and algal blooms
- Hussain Sagar — despite ongoing clean-up efforts, storm-water drain mixing keeps pollution levels high
- Saroornagar Lake (LB Nagar) — excessive nutrient loading has made it a persistent breeding pocket in east Hyderabad
Public health experts are urging the GHMC and other civic bodies to treat lake rehabilitation as a disease-prevention priority, not just an environmental or beautification project — particularly as monsoon conditions typically accelerate mosquito breeding across the city.
