A multimillion dollar desalination plant built to address water shortages in Sydney a decade ago may not be fully operational until next August.

As drought continues to grip New South Wales, Sydney’s dam levels are falling at such a rapid rate that the city’s only desalination plant could be needed for the first time since 2012.

Sydney’s total water storage fell to 65% this week, down about a quarter since last year. Warragamba Dam, the city’s largest water source, is at 68.3%. Twelve months ago it was at 90.7% capacity.