Lifeguards around the Big Apple are fearing shrinkage this summer — of their corps numbers.

As one-third of pools and beaches across the US could close down due to a shortage of lifeguards this summer, New York City is entering the same uncharted waters for the warm-weather season.

“Like the entire country, it’s been a challenge recruiting enough qualified people who can pass the NYC Lifeguard requirements, and pandemic impacts on recruitment continue,” NYC Parks spokesperson Crystal Howard told The Post, adding “at this time we plan to have all pools open.”

However, the national shortage could prevent about a third of the 309,000 community pools across the country from opening, according to the American Lifeguard Association.

An insider familiar with the situation confirmed to The Post that NYC, like in most recent years, is seeing fewer and fewer lifeguards looking out for the swimming public up in their towers.

The city will also have a more clear tally for its amount of lifeguards by the Fourth of July weekend when training is complete, the source added. At that time, NYC waters will be staffed accordingly off that lower-than-prior number.

Going off a daily headcount basis this summer, the department will also need to adopt flexibility when it comes to opening sections of beaches and pools. That’s in addition to figuring out which aquatic programs are feasible to be hosted, the deep diver added.

“We know New Yorkers depend on our pools and beaches in the summer — and we remain committed to ensuring that our facilities are open and usable,” Howard said.

This also comes in the wake of a Department of Investigation report that cited “13 recommendations to correct deficiencies in the management and operation of the Lifeguard Division,” the City reported.

That baker’s dozen of proposed changes focuses on bettering the corps’ disciplinary system to crack down on rule-breaking lifeguards. The DOI recommended implementing “intermediate managers” to “enhance supervision” for parts of the division.

Although the DOI published its hot water report in December, none of the suggestions have been completely implemented yet, according to the outlet.

“We continue to work cooperatively with DOI to address the report’s recommendations,” Howard told the City.