LOS ANGELES — Interior designer Nate Berkus has been adding fantasy to homes for 16 years, inspiring people with just the right creative touch. But he’s been a dog-lover even longer, and he’s turning his design expertise to a half-million-dollar fantasy dog park.

Berkus, 41, has joined the creative team for the 2014 Beneful Dream Dog Park Contest. Contestants have to answer one question: “If you had $500,000 to create a Dream Dog Park where you and your best buddy can play together, what would you do?”

In Lancaster, Pa., the answer included a doggy amusement park with a tennis ball tree and a 40-foot roller coaster bridge. The park there — the third contest winner — opens Aug. 6.

The first park was built in Johns Creek, Ga., with a family destination theme and includes a bone-shaped bridge, two splash pads, tunnels, rubberized mulch paths and shade trees. Johns Creek resident Pat McNeely entered the contest for his dog, Koda. The prize was used to renovate Newtown Park on Old Alabama Road in Alpharetta.

The second park in Alabaster, Ala., has synthetic turf, agility rings, a walking trail, a fetch football field, fire hydrant goalposts and a mulch adventure path with tunnels, said Brent Gleckler, brand director for Beneful dog food.

“There is nothing I love more than being with my dog,” Berkus said of sidekick Tucker, a black mutt. Together, they visit a dog park nearly every night.

The parks in Alabaster and Johns Creek have been tourist magnets. In Georgia, the city had to make 72 new parking spaces next to the park to accommodate visitors.

In Alabama, people take good care of the park, but the city does a walkthrough once a day, sprays it down twice a week and uses a biodegradable chemical once a month, city parks director Tim Hamm said.

The dog park is part the city’s flagship Veteran’s Park, with a ball field complex, 2.5-mile walking trail, eight pavilions with picnic tables, two playgrounds, a skateboard park and veteran’s memorial, Hamm said.

Every day, they get calls from tourists asking about hours and directions.

“The more people that come to our city, the more people will stop, eat and buy gas. We are all for that. Out-of-town users are great,” Hamm said. “Anybody who wants to come, we more than welcome them in town.”

Beneful has some requirements — large dogs must be separated from small dogs; the park has to be fenced for off-leash play; and it has to be a public or nonprofit park, open to the public at no charge.

“A park is a place for a community to come together. These parks are specifically designed for pet owners and their dogs, but everyone is welcome,” Berkus said. “We’re really looking at it from the dog’s perspective. We will use smart materials that will last a long time, and make sure we factor in pet behaviors and create not only beautiful fun places but intelligently laid out places as well.”

At Alabaster, the dog rules are typical of most dog parks: The off-leash area is for dogs, their handlers and those accompanying them, dogs have to be vaccinated, puppies and adult females in heat are banned and everyone has to clean up after their own dog.

Hamm said except for a few minor fights, there has been no trouble at the park. If there is a fight on your watch, the park has that covered too: A sign tells visitors “How to Break Up a Dog Fight.”

Berkus, who has an upcoming NBC show called “American Dream Builders,” is teaming up with contractor Jason Cameron, host of the DIY Network’s “Man Caves,” and Arden Moore, founder of fourleggedlife.com, for the latest contest.

So if Berkus were asked to design a $500,000 park for Tucker, what would he do?

“I would probably spend $495,000 bringing in squirrels because that’s what Tucker likes. He’s pretty simple. The sky is really the limit. It’s an enormous budget and an enormous contribution to the communities where these parks are built and it really is meant to be a fantasyland.”