On a 4-0 vote, the Los Angeles County Board of Supervisors upheld the Regional Planning Commission’s earlier approval of Mission Village, the second phase of the eventual 20,660-home Newhall Ranch “mini-city” west of Interstate 5 in the Santa Clarita Valley.

The decision came two weeks after the supervisors approved the first 1,444-home phase, named Landmark Village.

On Tuesday the board certified the planning documents and signaled its intent to approve Mission Village, which calls for 4,055 residential units – 351 single-family homes and a mix of 3,704 apartments and condos – plus 1.56 million square feet of retail and office space, recreation facilities, a fire station, a bus transfer station, library, school, utilities and roads. Also included are a preserve for the endangered spineflower and accommodations for 6,000 new jobs.

“We are pleased the board upheld the Mission Village approval. It is entirely consistent with the Newhall Ranch specific plan and will be a spectacular community,” said Marlee Lauffer, spokeswoman for the developer, The Newhall Land and Farming Co.

Supervisors heard the case Tuesday on appeal. Two environmental groups – Santa Clarita Organization for Planning and the Environment, and Friends of the Santa Clara River – asserted that Mission Village is inconsistent with the specific plan because it doesn’t include its own sewage treatment plant.

The supervisors denied the appeal.

Newhall Land’s Newhall Ranch project received conceptual approval in 2003 when supervisors approved its specific plan, but it sustained a series of subsequent setbacks including environmental lawsuits, intervention from state and federal regulatory agencies, a corporate bankruptcy and a market downturn.

Conceived in five phases of separate villages just outside Santa Clarita city limits, the project would add 70,000 new residents to the valley over 20 years.

After county planners approved the first phase (Landmark Village) in 2008, the U.S. Army Corps of Engineers raised concerns about encroachment on the Santa Clara River where endangered plants and animals live. By the time the supervisors reviewed the project Oct. 4, planned homes were pushed farther back from the riverbed.

The Regional Planning Commission approved the second phase (Mission Village) in May 2011. SCOPE and Friends of the Santa Clara River immediately appealed, asserting the project needs a sewage treatment plant, fails to address the chloride problem in the river, and doesn’t go far enough to protect the spineflower or safeguard air quality.

County planning staff members responded with a 2005 report showing Newhall Land is allowed to use an existing sewage treatment plant temporarily for up to 6,000 homes “as needed during construction” of a new treatment plant specifically for Newhall Ranch. “The Santa Clarita Valley Sanitation District has sufficient capacity to accommodate this use of its facilities,” the report states.

On chloride: “The interim discharge of wastewater from the Valencia (treatment plant) due to the Mission Village project’s wastewater would not impact the (sanitation district’s) ability to comply with the adopted chloride total maximum daily load,” county planners said.

The planning staff’s response noted that the appellants failed to say why they thought the measures to protect the spineflower and air quality were inadequate. Staffers detailed the ways in which the developer is required to safeguard them.