Environmental advocates are challenging the city over its approval of a land use plan that would allow taller buildings and more density near a sensitive coastal habitat in southeast Long Beach.

In a lawsuit filed on Thursday, the Los Cerritos Wetlands Land Trust claims the city violated state planning and zoning laws when it approved the Southeast Area Specific Plan last month. The lawsuit alleges the plan, known as SEASP, is in conflict with the city’s General Plan (a state-mandated document that contains a blueprint for local development).

The lawsuit also claims the city skirted a process required under the California Environmental Quality Act, which requires state and local agencies to identify significant environmental impacts of proposed projects and to avoid or mitigate those impacts, if feasible.

The SEASP document replaces an outdated plan that was first adopted in 1977. It governs a 1,486-acre area around Pacific Coast Highway, bounded by Seventh Street, Marine Stadium and Orange County, setting the standard for development in the area through 2060. As approved, the plan would permit the construction of 2.4 million square feet of commercial development and up to 6,663 residential units in buildings that may range in height from three to seven stories.

In an announcement released Monday, Executive Director Elizabeth Lambe called the update process a “missed opportunity” to protect a fragile environment. While the nonprofit’s board of directors applauded some elements of the plan — including measures that would ensure the safety of birds, creation of a wetlands mitigation fund and native plant landscaping — she said those protections don’t go far enough.

“There needs to be less density, lower height, less traffic and better and more science-based wetlands buffer protection around Los Cerritos Wetlands,” she said. “There is no way to achieve that goal with the current approved SEASP plan as it moves forward.”

City Attorney Charles Parkin said Long Beach had not yet been served the lawsuit as of Monday afternoon, and therefore could not comment on the case.

In the 22-page court filing, attorneys at Chatten-Brown & Carstens LLP laid out dozens of concerns with the environmental evaluation process with regard to impacts on biological resources, including sensitive species that make their homes in the coastal salt marsh, such as the tricolored blackbird, the Pacific green sea turtle and the coastal California gnatcatcher. Concerns over tall buildings, an influx of artificial light, and insufficient buffer zones between humans and wildlife are among the issues mentioned in the document.

In addition to the plaintiffs’ qualms with the environmental impact report, the Los Cerritos Wetlands Land Trust claims the city violated state law by approving a planning document that is incompatible with the city’s Land Use Element of the General Plan, a document adopted in 1989. The city is in the process of updating that plan as well, but community opposition to a proposed hike in density in new areas of the city has halted the process and sent planners back to the drawing board.