(NewsNation) — Memorial Day marks the unofficial start of summer for many but beating the heat at your local pool may be harder than ever this year. That’s because communities across the country are struggling to find lifeguards.

The shortage could prevent about a third of the country’s 300,000+ public pools from opening, according to the American Lifeguard Association.

“Like everybody else, if we don’t have enough lifeguards we have to shut down pools because we aren’t going to open up a pool that we know won’t be safe,” said Bill Plessinger, the aquatics manager with Westerville Parks and Recreation near Columbus, OH.

Last week, the parks department in Austin, Texas said it’s more than 500 lifeguards short of the number needed to operate city pools.

In some ways, the lifeguard shortage is a continuation of a problem that’s been going on for more than a year.

Last summer, Philadelphia only had enough lifeguards to open a fraction of its outdoor pools.

In Minneapolis, just three of the 12 public beaches had lifeguards last year.

The staffing challenges have left cities scrambling to fill open positions. Many are now offering incentives to get lifeguards to return to the watchtower.

In Chicago, seasonal lifeguards are eligible to receive a $500 retention bonus.

So what’s causing the shortage? Experts say it’s a combination of factors brought on by the coronavirus and the tight labor market.

In some cases, small municipal parks departments are struggling to entice workers with competitive wages.

“Other companies are coming in that are paying more money to these 16-, 17-, 18-year-olds. You’ve got to compete with Amazon and Target and Chik-Fil-A,” said Michael Johnson, the aquatics supervisor in Mecklenburg County.

Others NewsNation spoke to say there simply isn’t as much help as usual — the war in Ukraine has led to fewer young people coming over from Europe to work summer jobs through the J-1 visa program.

Experts point out that the problem has a way of compounding: fewer lifeguards also means less lifeguard training and fewer swim lessons.

For now, parks departments are hopeful that older Americans can fill the gap — retirees looking for a part-time job by the pool.