In a normal summer, Will Coleman, 44, and Thelma Nesbitt, 58, would each be overseeing 30 or 40 swimming pools in Philadelphia, staffed by dozens of lifeguards they’d recruit, train, and manage. Keeping all those swimmers safe is a big job — but it comes with a strategic advantage. When people don’t stick to the rules, they can blow a whistle and order everyone out of the water.

This summer, with the pools closed, they’ve been assigned a different role: social distance ambassador. Armed with free masks and information cards, they’re patrolling Philly parks trying to encourage visitors to mask up and stay safe.

They started the summer at Lloyd Hall near Boathouse Row. (“A lot of people didn’t want to be bothered,” Nesbitt said.) In June, they went down to FDR Park in South Philadelphia, offering safety tips to the skateboarders, picnickers, and Southeast Asian food vendors. (“People there were very receptive.”)

Their current assignment has landed them on the front line of a battle that seems to grow more pitched every year: for the soul of the Wissahickon.

The highly Instagrammable Wissahickon Valley Park, whose popularity long ago exceeded its parking capacity, this year has drawn more people, more cars, and more trash than ever before, as people seek refuge from the coronavirus and, often, a place to swim while city pools are closed. That’s collided with a sharply reduced presence by the Friends of the Wissahickon (FOW), which halted seasonal education staffing and volunteer work days due to the pandemic, executive director Ruffian Tittmann said. Fallout has included a “Bring Back Our Park Rangers” protest march by neighbors, and even a call by City Councilmember Curtis Jones to fill the park’s best-known water feature, Devil’s Pool, with rocks.

Car traffic on July weekends was up 37% compared with 2018, according to FOW’s counts. Park ranger Sahlee Brown said a single day saw 5,000 cars vying for about 100 legal parking spots. So, in August, police began blocking the entrances once lots were full, curing congestion within the park but sending drivers reversing back into the adjacent neighborhood in search of street parking.

“People are parking in people’s yards! Parking in their driveways,” said Parks & Recreation Commissioner Kathryn Ott Lovell said.

With those crowds, Nesbitt and Coleman can easily give out 500 face masks in a four-hour shift.

To prepare, they put on gloves — a football glove for Coleman, rubber gloves for Nesbitt. (“Some people have a phobia,” Nesbitt said.) Then, they muster their friendliest voices. “If they think we are policing them, it’s kind of hard to educate them then because they are not being receptive,” Coleman said.

Philadelphia Public Health Department estimates mask compliance outdoors in the city at 76%, based on studies of security footage at various locations. In Wissahickon Valley Park, a small fraction of people wear masks.

Giving out free face masks in a pandemic should be easy. But it turns out there are almost infinite ways to say no.

“I don’t have my wallet on me,” one man insisted, though no one was asking for payment. One woman said she won’t wear a mask outdoors, but is going to “keep her distance, and keep her mouth shut.” Some ignore the ambassadors, avoiding eye contact. A few, upon spotting the ambassadors, quickly put on masks they had stashed in their pockets, or even pull their T-shirts up to cover their faces as they pass by.

“I need to breathe,” said Lord Gothim, 46, who stopped on his bike to accept a free mask, explaining why he wouldn’t wear it while cycling. To Nesbitt, that’s still a win. “Sometimes we catch a biker. Sometimes they just look at you and start pedaling even faster.”

Nesbitt experiments with different ways to communicate that masks are available at no charge. “Free! They don’t cost you a penny. Zero!”

In the fall, Ott Lovell hopes to work with the Fairmount Park Conservancy and the city’s 120 park friends groups to enlist volunteers to take this social-distancing ambassador program to scale in parks citywide. “It’s an example of something that starts during a pandemic but is probably something we should have had all along: park ambassadors that support positive experiences in the park and also maintaining quality of life.”

After all, their challenges here intersect with a long-standing public-health problem. That’s Devil’s Pool, an idyllic spot where swimmers frolic in what Friends of Wissahickon emphasizes is a fecal-coliform-tainted cocktail of treated wastewater and stormwater runoff, incurring what rangers estimate are four or five serious injuries each year jumping from high rocks or an arched sewer conduit overhead.

Renee Adderly, a ranger, said many visitors are coming from New Jersey, or New York. They show photos they’ve found online, and ask for directions. “A lot of the information that goes out is misinformation. They think Devil’s Pool is actually a pool that they can go swimming in.”

With pools closed, Parks & Recreation dispatched workers to put all of the city’s 94 spray parks on automatic timers this summer, offering safe and reliable ways to cool off. They added warnings near Devil’s Pool, too. Visitors must pass at least eight “no swimming” signs, plus sandwich boards listing related rules: No swimming attire. No coolers.

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None of that deters a group of 20somethings, towels draped over their shoulders. Coleman jogs up to all of them, offering masks and advising them not to swim. They thank him and continue to the pool anyway.

Ott Lovell said enforcement isn’t the answer — in part because Philly has only 14 full-time rangers for one of the world’s largest urban park systems.

With swimming, as with mask-wearing, Nesbitt and Coleman said all they can do is educate, encourage, and hope it eventually sinks in.

The same goes for pandemic protection. “I’m quite sure they know they’re supposed to be wearing masks. A lot of people just choose not to or feel like they don’t have to because they’re outdoors. ... We have to encourage people to take care of themselves.”