As public amenities go, the dog park at Walsh Field, which turned 10 this week, hasn't been around that long. But in dog years, the birthday is significant.

On a sunny Sunday, most of the dogs playing in the open field were less than 5 years old. Many had come with their owners from surrounding towns, while others had recently moved here. At least one was tagging along on a family vacation.

A year-old German shepherd named Moxie ran circles with a 3-year-old Akita shepherd named Yogi Bear. A 2-year-old beagle French bulldog mix named Cashew jumped in when the action slowed to a speed that its short legs could match.

On an open stretch of the park facing Route 1, Dianne Johnson flicked tennis balls with a Chuckit! to her dog Walker, who would pick them up and drop them in place, forcing Johnson into a begrudging game of fetch.

"I manage to walk 2 miles to get the ball, so it's my exercise, too," she said.

Walker is a treeing Walker coonhound; however, Johnson said the he was named by her husband who likes to name dogs after photographers, in this case Walker Evans.

"His original name after we adopted him was Johnny Cash," she said. "I said, I'm not going to go through life with a Johnny Cash."

In the small-dog area, a wiry chihuahua poodle mix named Bella barked through the fence, in the way that one can bark confidently through a fence. Her owner, Sarah Ogle, said she occasionally brings the pint-sized dog into the larger part of the park, but less frequently than she used to, and always taking note of the other breeds.

"Catahoula leopard dogs think she's a rabbit," Ogle said. "Nobody's ever caught her yet, so that's a good thing."

Friends of Belfast Park, a volunteer group, raised about $50,000 to build the dog park in 2008. The site, tucked behind the baseball diamonds at Walsh Field Recreation Area on Lincolnville Avenue, had recently been given to the city by Bank of America.

Using the donations along with some volunteer labor and materials, the group cut down the overgrown field, ringed it in a chain link fence, installed two gazebos and even brought in a fire hydrant for the classic canine urination experience.

When it opened in August of that year, Carol Good of Friends of Belfast Parks said it was the only municipal dog park north of Portland. Since then, Good said, the group has shared information with organizations that went on to establish dog parks in Caribou, Brunswick, Camden, and some in other states, including Vermont and Massachusetts.

Good had three dogs when the park opened. Today she has one that is 13 years old and less active than it once was. As the younger dogs played in the park, Good and several of the other volunteers compared notes about what happened to other dogs that had inspired them to build the park. Some were still around, but many had moved away or died. Absent any context, it might have been the conversation at a class reunion.

"We've lost a few along the way," she said.

After maintaining the park in its first few years, Friends of Belfast Parks handed it over to the city. Good, who serves on the city's Parks Commission, said she's planning to update and reprint a 2008 "user guide" to the dog park, which has basic recommendations about how owners should oversee their dogs around unfamiliar animals.

When the park opened in 2008, there were 630 dogs registered in the city. Today there are 1,070, according to records at the City Clerk's Office.

"It's a whole new generation of dog owners," Good said. "It's a whole new community of dogs."