KARACHI, July 21: Strict and prompt action is required to block release of effluent from Kotri industrial area into the Kalri Baghar canal that feeds Keenjhar Lake which is a major source of drinking water for Karachi and Thatta residents, recommends a study.

The research ‘Water Quality Assessment and Characterization of Toxicity of Keenjhar Lake’ was conducted by the Environmental Monitoring and Modeling Division of Suparco (Space and Upper Atmosphere Research Commission) last year following contamination of a water channel (called Haroolo drain that flows into the Keenjhar Lake only during monsoon season) which caused death of a number of species.

An analysis of samples taken from the lake feeding sources (Kalri Baghar canal and Haroolo drain) showed that these two water bodies were the major source of pollution in the Keenjhar Lake and “are becoming threat to both lake’s aquatic life and human population relying on the lake water for drinking purposes”.

According to the report available on the net, cyanide traces were found in all the water samples but level of the chemical compound was high in the samples collected from near Toll Plaza (near Hyderabad) on the National Highway.

“Traces of lead and chromium were detected in each of the water samples of Kalri Bahgar canal. Significant concentration of lead (62.79 ppb) was found in the water sample collected from Rd-50 (a site located five to six kilometer from Kotri industrial area effluent discharge point) near head regulator,” the report says.

Significant concentrations of toxic metals were detected in sediment samples. The levels of fecal coliform, along with other toxic contaminants, were found higher in the samples collected from a site where Kotri industrial area effluent and Wapda Colony waste flowed into the canal water.

The study also refers to the samples collected by another organisation which found high concentration of urea in water samples collected from the affected section where animal deaths were reported.

“The cumulative effect of instant increase in the demand of dissolved oxygen (usually in the middle of the night when plant photosynthesis reverses and competes with the fish for oxygen), toxic metals (lead, selenium, nickel and arsenic) and urea due to flow of rain from the upper side of the drain into the affected section put a threat to the aquatic life and caused the recent killing,” it says.

The research calls for immediate action from the authorities concerned, including irrigation department, Karachi Water and Sewerage Board (KWSB) and Sindh Environment Protection Agency to block effluent discharge from Kotri Industrial Area into the Kalri Baghar canal.

The flow of Kalri Baghar canal to the lake, the study suggests, should be regulated in the light of pollution load in the lake water.

It also recommends for developing an action plan to prevent dumping of waste into the main channel of Haroolo drain or at least establishing some checks at the site to avoid mixing of rain water with the lake water.

Such an arrangement, the study says, would help avoid future incident of massive killing of aquatic life in the lower Haroolo section.

“Detailed analysis of surface and in-depth (vertical) lake water with the help of (GIS) Geographic Information System-based techniques is also required, besides devising a GIS-based monitoring mechanism of lake feeding sources. Such a system needs to be carried out every month jointly by all stakeholders (Sindh EPA, irrigation department and KWSB) and an external agency having expertise on the relevant subject. Early completion of the combined effluent treatment plant at Kotri is also needed,” it says.—Faiza Ilyas