India, May 21 -- Amid delays in a project to expand water storage capacity at the Wazirabad barrage on the Yamuna, Delhi's plan to tackle summer water demand with a buffer was also thwarted by a severe ammonia spike in the water level over the past fortnight, forcing authorities to flush down the polluted water to improve water flow and ensure fitness for consumption.

Officials said the dredging of the pondage area has been pushed to October, post monsoon. The dredging of the Wazirabad barrage has been on the agenda for authorities, given that it holds an estimated 363,000 cubic metres of silt, shoal and other material, removing it could bring its base level to 204 metres from the sea level.

An official of the Delhi Jal Board (DJB), who...