As Palo Alto's cramped but popular Junior Museum & Zoo prepares for a long-awaited expansion, city officials are struggling to reconcile the needs of the new zoo with their desire to protect the open space at Rinconada Park.

In an unusual nature-versus-nature debate, the city's Parks and Recreation Commission pondered, discussed and criticized the latest proposals to nearly double the size of the beloved museum on Middlefield Road, next to Walter Hayes Elementary School. The design calls for demolishing the 1930s building currently at the site and erecting a two-story building that, at nearly 20,000 square feet, would be more than twice the size of the existing museum. The goal is to equip the facility with adequate storage space, make it eligible for museum accreditation, improve site circulation and enhance exhibition areas and program spaces.

The goals are laudable, everyone agreed at the July 28 meeting. The museum, which is home to fruit bats, raccoons, two bobcats, and a giant tortoise named Edward, is often referred to as a Palo Alto "jewel." The fact that the renovation will be funded through private donations raised by a volunteer group, Friends of the Junior Museum & Zoo, makes the project a particularly easy sell for city officials.

Getting there, however, may pose a challenge. Because the museum is tucked between Walter Hays, Middlefield, a parking lot leading toward the Lucie Stern Community Center and Rinconada Park, space around the site is at a high premium. As such, the proposed design is forcing the city to weigh the relative benefits of an expanded Junior Museum & Zoo against the city's demand for parking spaces, its devotion to tree preservation and its professed desire to maintain neighborhood harmony.

In its latest discussion of the project, the Parks and Recreation Commission considered three different alternatives and found much to dislike about all three. Two of the alternatives would largely avoid infringing into Rinconada Park space but would each have so many complications that even the architects who proposed them conceded that they would create major operational challenges for the zoo.

One of the critical components of the expansion project is the creation of a separate building to support the zoo, which was built in the 1970s. One alternative would place the two-story zoo-support building in the middle of the proposed entrance plaza, effectively cutting off access to the museum complex.

Another would integrate the zoo-support area into the main museum building along Middlefield, making that building bigger and bulkier than it would otherwise be, and cutting into the parking area. Neither of these options got much traction from the commission.

The alternative preferred by the firm Cody Anderson Wasney Architects also didn't fare too well. Though deemed functionally feasible and somewhat better than the other two options, this design would situate the zoo-support building well inside Rinconada territory. The building would be separated from the main museum building by the zoo itself.

This design is similar to the one that was presented to the commission in February, though the museum's footprint in the park has been reduced by about 10 percent when compared with the earlier iteration. Even so, commissioners weren't too thrilled about sacrificing nature for a new building, even a building whose sole purpose is to foster an appreciation for nature.

Commissioner Ed Lauing observed that the city is now facing more demand than ever for its park space and that city efforts increasingly emphasize spaces that can accommodate a number of uses. The close relationship between the roles of the zoo and park in exposing families to nature did little to ease his discomfort.

"If the animals were spilling out occasionally, that would be one thing. But the building is going to be there and it is going to be there, kind of, forever," Lauing said. "Parks are about open space and trees and not necessarily about big buildings, and we can't endorse the use of limited park acreage just because something is fun and family oriented."

Commissioner Pat Markevitch had similar concerns about taking away park space. The city, she said, already falls short of its goal of having at least 3 to 4 acres of parkland for every 1,000 residents. She warned about the cumulative impacts of different building projects infringing on small portions of existing parkland.

"It's death by a thousand cuts," Markevitch said. "Our parkland is getting chipped away. We really need to draw a line in the sand as a commission at some point and say, 'Stop it.'"

While parkland is one concern, parking is another. Under the alternative preferred by Cody Anderson Wasney, which infringes into Rinconada Park, the existing 100-space lot would be expanded to 120 spaces. The other two alternatives, by concentrating the entire new complex around the current museum site, would cut into that benefit and push the new museum complex further into the parking lot.

"In all of these situations, something has to be sacred cows," Lauing said. "At this point, parking I think is one of them, sadly. And we're parks people, so we think trees are pretty close to sacred as well."

Among the most strident opponents of placing the new building in the park was Commissioner Deirdre Crommie. Like her colleagues, she praised the museum and called its offerings an "amazing program for our city." Yet she said she had an issue with putting a building in a park and was the only commissioner who favored a larger building along Middlefield.

"You're putting the building in the park and you're doing it because you don't want to put a building on Middlefield Road," Crommie told the project architects. "You're being very protective of Middlefield Road.

"I'm a little jealous because I live in south Palo Alto and no one is as protective about our roads," Crommie added. "We have big buildings going up all of the place in south Palo Alto but you get to the north and, 'Oh, it's residential. Let's not put a building on the road.'"

The commission did not vote on the project but requested that the architect make further revisions to the proposed design. Rob De Geus, director of the city's Community Services Department, defended the preferred alternative and highlighted the difference between the expanded museum and typical buildings. He compared the proposed structure to the type of interpretive centers that the city currently has at its open-space preserves.

"It's teaching thousands of children and families about conservation and nature," De Geus said. "These kids leave the Junior Museum & Zoo and the experience they have there caring deeply about parks and open space. There's huge value in that."