As the voices of Sinatra, Johnny Cash and Bobby Darin echoed through the humid air around the Edinborough Park pool, more than a dozen senior citizens marched in chest-deep water, flexing their joints and joining arms to sway back and forth to the music's beat.

There were more than a few artificial knees and hips submerged in the 84-degree water, and more than a few ticked-off seniors, too.

The shallow pool is threatened by a possible redesign of Edinborough, which is a city-owned indoor park. A consultant hired by the city has suggested the pool could be filled in to create more space for kid-oriented activities.

The suggestion has outraged people who use the pool for lap swimming and aerobics and stretching classes run by Edina Community Education. Many are seniors. They've flooded City Council members with letters of objection, and they're vowing to keep up the campaign -- and perhaps show up at a council meeting with their towels around their necks -- until a decision on the pool's future is made.

Edina resident Rita Acker, 81, said swimming in the pool strengthened her legs enough to allow her to delay a knee replacement for 10 years.

"It's very important to me, and the camaraderie is wonderful," she said. "Kids are wonderful, but do they need more space? Seniors need space, too."

Pool supporters say closing the pool would be hypocritical and counterproductive, as well as a slap to seniors, who make up almost 21 percent of the city's population. Along with Bloomington and Richfield, Edina is a so-called "" and is working with Blue Cross and Blue Shield to try to improve residents' health by encouraging them to exercise and eat right.

Recent retiree Cheryl Lany said the water classes have helped her connect with a new community as she begins a new phase of life. Day water classes at Edinborough are filled with regulars, sometimes followed by a group lunch. The classes draw people not only from Edina but from Richfield, Bloomington and occasionally Minneapolis.

"This is a city park, and this is something people over 55 want," Lany said. The city needs "to provide for everyone, not just for group sports," she said.

Edina has 40 parks, and none of the others are expected to make a profit, she said. Why, she asked, should Edinborough?

A winter haven

The aging park is unique in Edina and unusual for any city park, with its junior Olympic-sized pool, a running track lined by exercise equipment, multi-story play areas for kids, a 250-seat amphitheater and winding trails with little bridges that lead through grottoes shaded by more than 6,000 trees and plants.

Admission to the park is free, but paid admission is required to get into activity areas, including the pool and track. Thousands of people visit each year.

Last week, as the class of mostly seniors bobbed in the pool, some waved to toddlers who were on the other side of a glass wall, scooting around on little wagons, rolling balls and jumping in an inflatable bounce house. Adventure Peak, with tube slides and a climbing wall, was packed with kids and parents.

But this year, the park is expected to generate less than $1.2 million in revenue while costing $1.6 million to operate. At a joint City Council-Park Board meeting in January, consultant Jeff King of Ballard*King & Associates said that less than 4 percent of the park's admissions were for fitness activities.

The Edinborough pool ranges from 3 1/2 to 4 feet deep and has a lift that accommodates people in walkers. In addition to the eight aerobics classes per week, which cost $6.50 per session, there are lap swim times. The pool is also used by the Edina Swim Club and adaptive recreation programs.

Last year, 421 pool/track season passes were sold, and there were 2,919 paid pool/track admissions.

Consultant King said the pool is "one-dimensional," and that few people are interested in using a lap pool. The pool costs about $30,000 a year to operate, he said.

He indicated that part of the park's problem may lie with community perceptions.

"A stigma has developed around the facility, that Edinborough Park is a facility for children and kids at play," he said.

King pointed out that there's a YMCA with a pool near the park. He said if the city wants to keep the Edinborough pool, it needs to be "multifunctional," with slides and other attractions.

'The best-kept secret in the city'

One suggestion was to fill in the pool, replace the track with offices, remove all the plants (which require expensive greenhouse-type lighting to thrive) and fill in the grotto area with something like a Dance Dance Revolution or giant Wii program to appeal to older kids.

Seniors who use the pool say that if the pool is under-used, it's the city's fault. Several said they didn't even know the pool existed until their doctors recommended they check it out to help with orthopedic or fitness issues.

Lany said the city should aggressively market and promote the pool, not close it.

While the Y is just down the block, Acker and others said it is too crowded and seniors are intimidated by the busy parking lot.

Bill Bossert, 87, was leaving the Edinborough pool area as people limbered up in the water class. Though walking is difficult for him, he said, the disability vanishes in the water. He swims laps at the pool for an hour each day.

"This is the best-kept secret in the city," he said. "They're catering to the kids. I think they should give more concerns to their seniors."

Another discussion about the park's future is planned for a council work session on March 20.

Mary Jane Smetanka • 612-673-7380 Twitter: @smetan