NEW DELHI: Construction of weirs (low check dams) on drains flowing into the Yamuna have substantially reduced levels of pollutants such as ammonia and suspended solid wastes and brought down biological oxygen demand, the government said on Sunday.
“Construction of temporary weirs is proving to be an impactful approach to reduce the number of pollutants contaminating the contributing drains of Yamuna,” Irrigation and Flood Control minister Satyendar Jain said.
The minister said the department is focusing on solving the problem of polluted drains flowing directly into the Yamuna River, which will lead to its cleaning. The government has set a target to clean the river by March 2023, he said.
It has started work to improve the quality of Najafgarh drain water that enters Delhi at Dhansa and travels about 57 km before falling into the Yamuna, and its supplementary drain, which takes off from near Kakrola Regulator and falls into the Najafgarh drain.
So far, the construction of 11 weirs has been completed on the supplementary drain and three on the Najafgarh drain. Work on 10 weirs is in progress, the statement said. According to it, a test report submitted by the Irrigation and Flood Control department found that total suspended solids went down from 166 mg/L in Rithala to just 49 mg/L in Rohini Sector 15.
The water samples were collected near Rithala STP, Rohini Sector 11 Weir, Rohini Sector 16 Weir, and Rohini Sector 15 Weir. The biochemical oxygen demand (BOD), which represents the organic material contamination, was found to be reduced after each weir.
The department has also employed desilting of the drains, installation of trash barriers, floating boom to trap solid materials, removal of municipal solid waste and construction waste from drains, among other steps to clean the river.