Our lakes are dying...and the fish too!

Sowmya Raju | NT

Bengaluru: The pre  - monsoon showers which Bengaluru witnessed recently, have also exposed another serious problem - some of the city's lakes are witnessing fish deaths on a massive scale.

Incidents of fish gasping for air on the surface of the water and fish kills in Doddakallasandra Lake and Kothanur Lake in South Bengaluru, have become a cause of concern for several ecoactivists and are a pointer to the lack of dissolved oxygen in the water.

Insufficient management practices for lakes such as neglecting regular desilting and maintenance, can lead to a decline in oxygen levels. Raghavendra B. Pachhapur, representing ActionAid, has identified this as a critical factor in the lakes where numerous small aquatic plants usually thrive. These plants play a vital role in oxygenating the water, but their absence has resulted in a reduction of dissolved oxygen harming the fish.

Don't throw trash in lakes Pachhapur goes on to explain the situation at Doddakallasandra Lake that is currently at a critical juncture and is facing the risk of becoming a perpetual reservoir of pollution due to sewage inflows from various stormwater drains. The recent heavy rainfall has resulted in an influx of garbage and sewage, further deteriorating the lake's condition.

The accumulation of garbage around the lakes can pose a significant threat to aquatic life. Pachhapur reveals that the lake's diversion channels, designed to filter sewage water before it enters the lake, were installed two years ago with the intention of monthly cleaning and thorough maintenance before the monsoon season.

Unfortunately, these channels have not been cleaned for two years, resulting in the accumulation of silt. This has led to pollution of the lake with garbage and sewage, adversely impacting aquatic life. The blame should be partly laid at the doors of the Bangalore Water Supply and Sewerage Board (BWSSB) which has not yet laid the sewerage network all across the city. So many of the pipes carrying sewage enter lakes despite instructions by the Karnataka State Pollution Control Board to the contrary.

The inadequate efforts by BBMP in cleaning Kothanur Lake and Doddakallasandra Lake are also to blame. Instead of properly disposing of solid waste, the BBMP collects it on the lake bund. Once the garbage dries up, it flies into the lake with even a gentle breeze rendering the cleaning efforts futile.

Moreover, the presence of plastic and glass pieces on the garbage bunds poses a potential threat to the fish, leading to fish kills. The aquatic life at Chellekere Lake is now completely destroyed by the heavy flow of sewage from the stormwater drain. The lake now has no scope for aquatic life since it is filled with garbage.

The occurrence of fish kills in lakes is a pointer to shabby sanitation management, poor commitment to lake conservation, and the failure of pollution prevention efforts. However, instances of fishkill can be avoided if BBMP, BWSSB, and KSPCB collaborate and work together in a coordinated manner, say experts adding that it is essential for these organisations to join forces and address the underlying issues to ensure proper lake management and prevent fishkill.