On a recent weekday at noon, a short queue of people in masks holding tote bags and beach towels waited outside the gate of the Waltham YMCA’s pool. A staff member wearing a bandana over her nose and mouth cheerfully greeted each person who stepped into a canopy tent and checked their name off of a list of pool-goers who had made reservations. After scanning each person's forehead for a temperature check, she told them which table and swimming lane they were assigned to.

Online reservations, temperature checks and masks are the only way anyone gets beyond the gates at the outdoor pool, which reopened earlier this month when Gov. Charlie Baker announced the state would move to Phase 2 of his administration's 4-phase reopening plan. Outdoor pools were allowed to open in this phase, along with some other summer favorites including playgrounds and summer camps.

But reopening pools comes with challenges, prompting some towns to opt out altogether this season, keeping their pools closed because of the pandemic. It's a tough outcome for Massachusetts residents who don't have easy access to beaches or other ways to cool off. Other towns are still figuring out logistics for plans to open later in the summer.

Donny Bautz, the Waltham Y's senior executive director, said assigned swim lanes and tables — called “stations”— are just a few of the factors he and his staff had to consider when preparing to reopen.

With social distancing guidelines strongly enforced, only eight families or individual members are allowed in at a time, and only for 45-minute time slots. Numbered tables are spread far apart around the pool. Opposite the entrance, a common area that usually offers more space for members to hang out has been closed off. Dozens of recliner lounge chairs are stacked there instead.

To go for a dip, swimmers have to stick to their own lanes, marked by floating dividers across the width of the pool.

“We have our pool that is sectioned off, where every family or every lap swimmer has its own space,” Bautz said. “After the 45 minutes, they are asked to exit through a separate exit than where they came in.”

It was the pool's first full week open again, and Bautz said all of the time slots were fully booked three days in advance. The pool is for members only — reason enough for Waltham resident Lisa Sargavakian to get a family membership.

“It’s been a challenge. My daughter — she’s an only child, my husband and I are both working from home. So she’s been on her own, left to her own devices, literally and figuratively for the last few months. It feels really great because it gives her an outlet at least for an hour every day,” Sargavakian said.

When time is up, the lifeguards make it clear, blowing their whistles and telling everyone to hop out.

For the next 15 minutes, the staff sanitizes the entire area. This happens every hour.

Other pools are instituting similar routines, and this means that they can accomodate far fewer people than usual. In Needham, the parks and recreation department recently announced it will open its pool this year, but only for town residents. Last summer, approximately 50,000 people used it. This year, Cyndi Roy Gonzalez, the town's public information officer, anticipates that number to hover between 4,000 and 5,000.

One additional challenge in getting ready to reopen involves training lifeguards while adhering to social distancing guidelines. Typically, the pool trains 20 lifeguards at a time. Now, only five can be in the pool per training.

"Lifeguards typically rescue each other in a training. This year we have asked them to bring a friend — someone they've been close with, to practice rescues," Gonzalez said.

The 36 pools operated by the state Department of Conservation and Recreation remain closed, but the agency told WGBH News that it expects to finalize its reopening plans by the end of June. The city of Boston is still figuring out what to do with its two outdoor pools.

Other recreation departments across the state have decided not to open their pools this season for both safety and financial reasons. That includes the town of Belmont. During a typical summer, about 200 people would be cooling off in the Belmont town pool at any given time. After crunching some numbers, Jon Marshall, Belmont’s assistant town administrator, said they would have had to charge residents more to spend less time in the pool.

“We’re in the middle of a pandemic, so these are very different times,” he said. “In order to make it work economically, we were looking at about $17 per person.”

It's a steep price for only two hours of swimming. Unlike the YMCA, which has membership dues and program fees, town pools rely on season and day passes. Factor in town budget cuts, and it just wasn’t feasible to open the pool. The decision that was met with mixed reviews.

“There were people who were certainly disappointed. It was also nice to hear from a number of residents that understood based on the info that was available why that decision was made,” Marshall said.