A Kalispell triathlete who last year became the third person ever to swim the length of Flathead Lake has set the bar higher this summer as she attempts to swim the 55-mile-long Lake Chelan in northern Washington.

If Emily von Jentzen, 28, accomplishes her goal on Aug. 31, she would become the first person ever to swim the long, narrow expanse of Lake Chelan, the third deepest lake in America.

“I’ve talked to quite a few people and I’m pretty sure no one has ever swam the entire length,” she said. “There are no records I can find.”

She swam Flathead Lake in 18 hours, 26 minutes, covering roughly 33 miles. Flathead is 27.3 miles long, according to Flathead Biological Station, but Jentzen accumulated some extra mileage when the wind put her off course.

Lake Chelan is twice as long as Flathead Lake and also can be prone to wind and rough water. She has calculated the swim will take 26 to 28 hours.

The temperature of Lake Chelan is comparable to Flathead, where the water temperature was in the 70s when she swam the lake last July. Lake Chelan’s north end is colder, about 65 degrees this time of year, while the water temperature in the southern end is about 10 degrees warmer.

Von Jentzen decided on Lake Chelan because she’s got family members in the area who can help with the crew and lend their support.

Just like last year, there’s an added element to von Jentzen’s mission: She’s using the endurance swim to raise money for a young girl with cancer. This year’s fundraising recipient is Katelyn “KK” Roker, a 5-year-old from Kalispell who is battling Stage 4 neuroblastoma, a high-risk cancer.

After getting to know Katelyn, von Jentzen discovered that Katelyn and Karmyn Flanagan, the Missoula girl who benefited from last year’s fundraising swim, became friends while both were getting cancer treatment in Spokane.

If Karmyn is well enough, she and her family may travel to Lake Chelan to cheer her on, von Jentzen said.

Von Jentzen, a deputy county attorney for Flathead County, is writing about her intense training program on her blog, at http://alakkeforkatelyn.blogspot.com. Her slogan, “A Lakke for Katelyn,” honors the girl’s nickname, “KK.”

After completing her first-ever running marathon in May at the Nashville Rock & Roll Marathon, she dove headfirst into a 17-week specialized training program, alternating two weeks of hard swimming with one week of recovery.

“Today’s swim was just a 7,000-meter swim at Splash Montana that put my total for the week over 40,000 yards,” she reported in Sunday’s blog entry.

Last week she got in a five-hour swim in Lake McDonald in Glacier National Park, noting “the water was fairly chilly, but I didn’t mind it too much.”

This year’s late summer kept her swimming indoors longer than she wanted.

“I just started outdoor swimming about three weeks ago,” she said, adding that the first couple of outdoor sessions were done in water temperatures in the 50s.

Von Jentzen wasn’t sure she wanted to take on another record-breaking swim this year.

“Last summer, training encompassed my whole life,” she said.

But when she heard about a “Kupcakes for Kancer” fundraiser for Katelyn in May and learned about her battle with cancer, her mind was made up.

“If there was ever a kid that needs help it’s her,” she said. “Her fight is pretty intense.”

The daughter of Brian and Jaime Roker, Katelyn was diagnosed with the disease in January 2010 after a doctor discovered a lump on her neck and further tests found a grapefruit-sized tumor wrapped around her aorta. Since then Katelyn has endured several rounds of chemotherapy, tumor resection surgery and a stem-cell transplant.

Von Jentzen would like to raise at least $9,500 for the Roker family. That’s the amount she raised for the Flanagan family. She’s hoping for some national media coverage that could boost her fundraising efforts. Because there’s no record of anyone ever swimming Lake Chelan, it could put her in the spotlight.

In Kalispell, an account called “A Lakke for Katelyn” has been established at First Interstate Bank for those wanting to donate to the family, or there’s an opportunity to donate online on von Jentzen’s blog.

Von Jentzen is no stranger to distance swimming and endurance events.

Motivated to be a swimmer at age 9 in Lake Stevens, Wash., “because it was the only sport I could beat my sister at,” von Jentzen swam her way through high school with top honors in swimming and swam at regional competitions in California and Hawaii for the Pacific Northwest Swim Team.

She earned a swimming scholarship to Central Washington University, and when the university cut its swim team, she and her teammates started their own team to allow them to keep on competing.

About the same time, von Jentzen began competing in triathlons — swimming, bicycling and running in a single competition.

Features editor Lynnette Hintze may be reached at 758-4421 or by email at lhintze@dailyinterlake.com.