Jason Beakes raises his paddle like a spear as his kayak teeters over the edge of a 15-foot cascade in the middle of Great Falls. Surrounded by slick, black rocks, he charges down the narrow chute of roaring white foam, airborne for an instant, and bounces gently as he lands in the frothy pool below.

Beakes was practicing for Saturday’s annual kayak race down Great Falls’ Class V+ rapids, a contest he has won six times. The sight of him and his friend repeatedly diving over the rocks drew spectators on both banks of the river, as visitors to the national parks in Virginia and Maryland stopped to watch, take photographs and applaud.

U.S. Park Police were there, too, watching with binoculars. Such displays have long made National Park Service rangers cringe, fearing that observers might think it’s okay to kayak over the falls, which is for experts only, or to go swimming in the river, which is illegal. Fourteen people have drowned in the Potomac River Gorge in the past two years.

But after decades of tension between park rangers and daredevil river runners — marked by shouting matches, threats of fines and the controversial arrest of an Olympic paddler — the kayakers and the Park Service have charted a new course: working together to keep the river safe.

Beakes, who called the Park Service rangers before running the falls this week, is one of 11 experienced kayakers in the Potomac Paddlers Volunteer Corps. The new program, years in the making, trains the kayakers to help the Park Service patrol the river — responding to and preventing dangerous or illegal activity, including swimming and wading.

“The authorities are realizing that maybe people like us kayakers are a real solution to a lot of these problems,” said Beakes, 38, an infrared technician whose arms and torso attest to his hours spent battling the Potomac’s currents. Many park rangers “used to see a guy like me and think, ‘He needs to be watched so he doesn’t do something dumb.’ Really, it’s people who are just walking into the park and don’t know how to be safe.”

Testing the limits

Kayaking over Great Falls was thought to be impossible until Tom McEwan and a group of friends did it in 1975. McEwan, director of the Liquid Adventures Kayak School in Cabin John, said those early runs often ended with park rangers intercepting the kayakers and yelling at them.

“After that, we would usually try to stop in and give the park rangers’ office a heads-up so they wouldn’t immediately go for a helicopter,” said McEwan, 65. “We kept a low profile for a long time because we were afraid that if we got a lot of other people out there, the Park Service would not like it and would shut us down.”

But inevitably the falls started attracting more and more kayakers, and they kept pushing the limits — finding new lines of rapids or running the length of the falls without stopping. “Then someone said, ‘Let’s race,’ ” said Andy Bridge, who organized the first Great Falls race in 1988.

It became an annual tradition and, since 1991, part of the Potomac Whitewater Festival.

The Park Service always permitted the race but wanted it held early in the morning so it wouldn’t draw too many spectators, who then might be tempted to climb out on the rocks or go in the water. But many of the kayakers wanted to pursue their sport on their own terms and schedule.

“It’s like the basketball hoop at the end of your block — you just want to be able to go all the time,” said Risa Shimoda, who chaired the committee of volunteers that organized this year’s festival.

The friction between the Park Service and the kayakers went beyond the race. Most notoriously, in the winter of 1996, the Park Service closed the parks because the river was flooding.

Davey Hearn, an Olympic paddler, and a few friends went out paddling anyway, and Hearn was charged with resisting arrest and failure to obey an officer. The case went to court but was thrown out.

“There was a lot of lingering tension after the Davey Hearn incident,” said Paul Schelp, who was on the river with Hearn that day. “That was humiliating for the U.S. Park Police.”

‘Common ground’

Schelp said there has always been a good relationship between some of the kayakers and park rangers but never any organized dialogue.

That changed last summer, when the Park Service and the kayakers did something radical: They met.

That initial step, to discuss a logjam blocking the main access point to the river from the Virginia side, led to more discussions about safety on the river that continued throughout the year, and in May the Park Service officially launched the Potomac Paddlers Volunteer Corps.

“It was a recognition of common interest and common ground,” said Brent O’Neill, the site manager of Great Falls Park, on the Virginia side. “We all take interest in what’s going on on the river, to protect the resource, to protect access and to reduce the risk of incidents.”

When the kayakers go out on patrol, they first call the Park Service dispatch to say that they’ll be on the river. They keep an eye out for unsafe behavior and submit an informal e-mail report when they are done.

In May, the volunteers logged 27 hours of safety patrol. The numbers for June — when they have helped prevent several dangerous situations — are higher but haven’t been tabulated yet, O’Neill said.

Shimoda once approached a father and son who were preparing to launch an inflatable boat, the kind sold at convenience stores. Shimoda advised them that the river was running high so there would be a high risk of capsizing.

“They decided to go home,” she said. “The 7- or 8-year-old boy was very disappointed. But the dad knew there would be another weekend.”

The volunteers have also helped rescue people whose canoe capsized canoe and convinced two fishermen who were in the water up to their necks that they should leave the river.

“They’re being our eyes and ears,” Aly Baltrus, supervisory park ranger at the Chesapeake & Ohio Canal National Historical Park, on the Maryland side, said of the volunteer kayakers. “It seems like people are listening to them, and if they can stop it there we don’t have to get law enforcement involved.”

The organizers of Saturday’s race say they expect at least 20 kayakers and 50 spectators. The location will depend on the water level, which is the highest it has been in more than five years.

For the first time, the Park Service will be at the festival, side by side with representatives of kayaking schools at booths offering information about paddle sports and being safety in the park.

“The Park Service is endorsing kayak sports as a safe way to enjoy the river,” Beakes said. “It’s a radical shift.”

The festival will also include a video presentation about the rules of the park and the history of kayaking on the Potomac, including Hearn’s famous arrest.

“Advanced and expert paddlers, we’re in the same boat together with the Park Service,” Hearn said.