There is a significant risk that the water level in Johor's Linggiu Reservoir could fall to zero if 2017 is a dry year, said Foreign Minister Vivian Balakrishnan yesterday.
The water level in Linggiu Reservoir stood at 27 per cent as of Jan 1, he said in a written reply.
Its water level has dropped drastically over the past few years, from 84 per cent at the start of 2015 to the lowest recorded level of 20 per cent in October last year.
Should the Linggiu Reservoir fail, there will be "many more occasions" when it will not be possible for national water agency PUB to draw its entitlement of 250 million gallons per day from the Johor River, he added.
Mr Seah Kian Peng (Marine Parade GRC) had asked whether the recent low water levels would affect the ability of both countries to meet their obligations under the water agreement.
Dr Balakrishnan said the water supply to Johor's Semangar and Loji Air water treatment plants will also be affected, adding: "This will cause severe problems for both Malaysia and Singapore."
The Government is watching the situation closely and has raised the matter with the Malaysian government, most recently at last month's Leaders' Retreat. Singapore will cooperate with Malaysia to achieve a "mutually beneficial outcome", he said.
Officials will discuss and identify possible solutions, he added.
"Our agencies have an excellent working relationship, and will continue to work closely together to sustain our water supply," he said.