A nonprofit housing group has filed the first of what is expected to be several lawsuits challenging the rezoning of San Francisco’s Central South of Market area, suits that could significantly delay the development of more than 6 million square feet of office space and thousands of housing units.

In the lawsuit, filed in San Francisco Superior Court on Monday, the Yerba Buena Neighborhood Consortium, the legal arm of the affordable housing group Todco, argues that the plan’s environmental study was inadequate because it didn’t take into account the impact the neighborhood changes would have on public services such as police, fire and recreation.

“The Central SoMa plan environment impact report completely failed to consider the impacts of first adding 50,000 more people — 20,000 new residents, 30,000 workers — to Central SoMa and what demand that would create for all the public services you’d need for a population that size,” Todco Executive Director John Elberling said. “This was totally ignored.”

In addition, the lawsuit claims that the environmental study neglected to analyze the potential “grave earthquake dangers” that exist in the Central SoMa neighborhood, much of which is built on fill. Elberling said legislation should have been drafted alongside the Central SoMa plan that would require seismic reinforcement of all buildings in the plan area.

“If you have bad luck on the day of the earthquake, a lot of people will be on the sidewalks or working in some of the older buildings,” he said. “They will be in serious danger.”

After seven years of planning and debate, the Board of Supervisors last month rezoned the portion of South of Market that extends from Market Street south to Townsend Street and from Second Street to Sixth Street. The plan, which runs along the future Central Subway line, will eventually allow for about 9,000 housing units and enough office space for 30,000 workers.

The rezoning sets the stage for a number of major redevelopments, including 2 million square feet of office space that would be built at the S.F. Flower Mart — along with a new wholesale flower market — as well as a mixed-use project at the San Francisco Tennis Club at Fifth and Brannan streets, which would include 100 affordable housing units, a public swimming pool and recreation center, and 833,000 square feet of office space.

The deadline for filing a legal challenge to the plan’s environmental study is Thursday, and as many as three other lawsuits could be coming. The South of Market Community Action Network opposes the plan, claiming it will lead to higher rents and further gentrification. David Woo, community development coordinator for the group, said, “We are still weighing strategy and deciding whether or not to appeal.”

Another likely lawsuit could be filed by Jonathan Berk, a professor of finance at the Stanford Graduate School of Business who heads a group called Central SoMa Neighbors. Berk, who lives in the penthouse at Blu condominiums at 631 Folsom, has opposed the rezoning on the grounds that it allows excessively tall and dense buildings. Berk could not be reached for comment.

Finally, One Vassar LLC, the developer of a proposed housing, office and hotel development at Second and Harrison streets, plans to sue on the grounds that the plan should require more height and density than it allows. Evette Davis, spokesperson for One Vassar, said that the company would be “filing a lawsuit before the deadline.”

Even with multiple lawsuits holding up the plan, the city Planning Department will continue to work on approvals of the individual projects in the plan area, according to department spokeswoman Gina Simi.

“A lawsuit shouldn’t change the approval process for individual projects,” she said.

Though the individual projects are all likely to be approved eventually, the limit imposed by Proposition M from 1986 — which caps the amount of new office space that can be approved in a single year — means not all of them can win entitlements at once.

Prop. M allows the city to approve 875,000 square feet of office projects a year, space that accumulates during economic slowdowns but is quickly depleted during booms.

Currently, 2.9 million square feet are available under the cap — 2.7 million square feet shy of the 5.6 million square feet proposed by developers in the Central SoMa area. That means the city will have to determine which projects can be approved right away and which will have to wait a year or two until more space is available.

Even if there were no lawsuits, the realities of the time required for approvals and permitting in San Francisco means it’s unlikely that any construction would start before 2020. Elberling added that delays beyond that could be avoided if the city agrees to community demands.

“It’s up to the city. If the city wanted to work with us and address the problems, it would be finished this year,” he said. “If we resolve the problems this year, we could drop our lawsuit.”

The 6 million square feet of office space is in high demand, said Robert Sammons, research director for commercial real estate broker Cushman & Wakefield. Currently there are 121 tenants looking for 5.2 million square feet, Sammons said. With the exception of the Oceanwide Center at First and Mission streets, which will include 1 million square feet of office space, all the significant office projects under development have been completely pre-leased.

“We need the space — we have a lot of tenants in the market,” he said. “We have backed ourselves into a corner in that all the space was pre-leased and never saw the light of day. There are fewer and fewer choices.”

J.K. Dineen is a San Francisco Chronicle staff writer. Email: jdineen@sfchronicle.com

Twitter: @sfjkdineen