Over the years there has been a lot of rhetoric on the conservation of the Upper Lake, believed to be country's largest city-based lake. However, there was no comprehensive report which could reveal the status of the lake in its totality.
The void has been filled by a detailed project report (DPR) of the Bhopal Municipal Corporation (BMC), which shows how the lake is dying slowly.
After getting rapped by Bhopal bench of the National Green Tribunal (NGT) on many occasions, the BMC finally submitted the summary of the DPR for conservation, management and development of the Upper Lake to NGT on August 6.
The DPR is based on the interim report of Gujarat-based Centre for Environmental Planning and Technology (CEPT) University, on master plan of the Upper Lake. The final report of CEPT is under consideration of urban administration department.
The report reveals that the biological oxygen demand (BOD) level in the lake has reached 9 mg per litre from the Bairagarh side in Bhopal, crossing the threshold value of less than 3 mg/litre. The BOD measures the amount of oxygen consumed by microorganisms in decomposing organic matter.
According to the experts, BOD directly affects the amount of dissolved oxygen in a water body. This is a cause of great concern as BOD means oxygen in the water is getting depleted rapidly. Due to the high BOD, the aquatic life gets stressed, suffocated, and may ultimately end.
The report further points out that lake has turned 'eutrophic' and needs immediate action to prevent further deterioration. Eutrophication means enrichment by or excess of nutrients in the water. This may result in an explosive growth of algae and lessening of oxygen, which harms or kills aquatic life.
These nutrients enter the lake from its catchment area like agriculture runoff and sewage water and idol immersions. According to the report, the siltation in the lake has also reached almost one-metre depth.