The City Council voted 13 to 0 to certify the environmental impact report for the city-owned facility. Zoo officials want to upgrade the 1960s-era facilities, expand conservation efforts and add more space for animals.

Key details of the makeover remain unknown after zoo officials said in June they would explore other options in the face of the opposition over construction that would cut into the hills.

Without final designs, the renovation’s cost — which would be paid for with private and public funding — is unknown. An earlier estimate put the initial phase of construction over the next few years at $650 million.

The plan the council signed off on Wednesday also estimated that nearly 300 employees will need to be hired at the zoo over the next 18 years because of the additional facilities.

Councilmember Nithya Raman said in a statement before Wednesday’s vote that she expects the zoo, which is in her district, to continue to work with local groups on the plans. Her office also provided a fact sheet from the zoo that said a controversial planned visitor center wouldn’t be built on a ridgeline on the zoo property.

“Given the zoo’s willingness to respond to community feedback, I feel confident that as they develop detailed project designs, that any additional concerns can and will be addressed,” Raman said. “My staff and I are committed to continuing to work with them, and elevating community concerns, as we have throughout the process so far.”

The environmental analysis for the zoo’s renovations started several years ago as zoo leaders sought to transform the facility and get ready for tourists expected during the 2028 Summer Olympics. Earlier, flashy proposals, including adding an aerial tram, a Yosemite National Park-style lodge and a parking structure, were scrapped, however.

The first phase of the most recent proposal would include an expanded elephant exhibition, programs around California’s wildlife, the new visitor center and an entry building. An additional 300 parking spaces and a parking program are also in the proposal.

Denise Verret, director of the Los Angeles Zoo and Botanical Gardens, said in a letter in June to council members that the plans represent a “significant milestone in the zoo’s history to innovate and transform the physical campus into a modern zoological facility for future generations of Angelenos” and noted other zoo goals around accessibility and conservation.

Verret’s letter also said the zoo is committed to making changes to its plans, including scaling down the visitor center — at one point, it was more than 15,000 square feet, according to opponents — and reworking a proposal to cut 60 feet into the hills for a condor-themed “canyon.”

Both the Santa Monica Mountains Conservancy and the Federation of Hillside and Canyon Assns., which represents 47 resident associations spanning the Santa Monica Mountains, had criticized those elements.

Gerry Hans, president of Friends of Griffith Park, said he’s glad to see earlier elements were nixed. But he still isn’t satisfied with the zoo’s proposal, which includes the development of 16 acres of hillside.

“We really tried to persuade the zoo, persuade Council District 4, to keep working on not impacting all the habitat that is there,” Hans said.