[9] The sphere of influence is a municipal growth boundary that delineates the area that the Local Agency Formation Commission (LAFCO) believes is the appropriate and probable future city limit.

[10][7] The 1990 LA County General Plan Update identified the unincorporated area of Newhall Ranch for urban development.

[14] In 1998, Valencia area had 1.1 million square feet of industrial space under construction with a 2% vacancy rate in the existing developments.

The unincorporated area northwest of the intersection of Interstate 5 and State Route 126 had plenty of acreage and entitlements to accommodate additional industrial space.

The residents of the unincorporated communities of Sunset Pointe, Stevenson Ranch, Southern Oaks, Westridge, Tesoro, Castaic and Val Verde were able to weigh in their preference.

[24] The developers of the Newhall Ranch project had hoped to break ground by 2012 but several lawsuits were filed over the years by various environmental groups, and other interested parties.

The landmark California Environmental Quality Act, or CEQA, was used to challenge the development even after the county had approved the specific plan and the zoning changes needed for the project.

The area provides habitat for a wide array of native plants and animals including threatened and endangered fauna and flora.

[31][8] The plan includes converting nearly 20 miles (32 km) of tributaries and riverbank into storm drains and levees and use 20,000,000 cubic yards (15,000,000 m3) of excavated soil to fill in wetlands.

[32] The Newhall Ranch Sanitation District will operate a water reclamation plant serving the development near the boundary with Ventura County.

[33] The plant will treat an estimated 6,800,000 US gallons (26,000,000 L; 5,700,000 imp gal) of water every day before releasing it into the Santa Clara River as it flows towards the ocean and into Ventura County.

The ruling also supported the agency's determination that storm-drain runoff from the project's 2,587 acres (1,047 ha) into the Santa Clara River would not harm juvenile steelhead trout downstream in Ventura County.

[38] Also of concern is that participation in land-use issues is discouraged by requiring that public comments be submitted early in the environmental review process rather than up to the time of project approval.

[42] The California Supreme Court ruled in November 2015 that Newhall Land Development Inc. failed to provide evidence in its overall Environmental Impact Report (EIR) to prove its project was consistent with state guidelines to control greenhouse gases.

After changes had been made addressing the Supreme Court's concerns, the California Department of Fish and Wildlife certified the environmental impact report in 2017.

[52][19] Entrada North is a development with 1,150 multi-family residential units built around a town center with shopping, dining and entertainment.

It is bounded on the west by the Ventura County line and on the east by Interstate 5, which also marks the border with the neighborhood of Valencia in the city of Santa Clarita.

The area provides habitat for a wide array of native plants and animals including threatened and endangered fauna and flora such as the California condor, the California gnatcatcher, the southwestern willow flycatcher, the least Bell's vireo, the arroyo toad, the San Fernando Valley spineflower, and the threespine stickleback.

[57] College of the Canyons and California Institute of the Arts are located nearby, in the Santa Clarita city neighborhood of Valencia.

The entire Santa Clarita Valley, including Valencia, is in the Fifth District of the Los Angeles County Board of Supervisors, represented by Kathryn Barger.