The West Coyote Hills was once a major oil field, dating back to 1890. Extraction has long since ceased, and most of the West Coyote Hills has been developed for residential and commercial use, as well as West Coyote Hills Park. A tract measuring across the ridge of the hills, owned by Pacific Coast Homes (a land development division of the
Chevron Corporation), is the largest remaining tract of undeveloped land in north Orange County. Pacific Coast Homes plans to build 760 homes on , while restoring and donating 352 acres to the City of Fullerton for use as the Robert E. Ward Nature Preserve. A group called Open Coyote Hills has been leading the support while a group called Friends of Coyote Hills has led the push to preserve the entire site as open space. In 2012, Fullerton voters voted to prevent development in a referendum, Measure W. Lawsuits have resulted over the interpretation of the measure. The city council has a pro-development majority, which has sided with Chevron, and won in Superior Court, but the decision has been appealed. In 2017, State Senator
Josh Newman authored Senate Bill 714, which would create a West Coyote Hills Conservancy with initial funding. In 2021, the City of Fullerton purchased the eastern portion of the land adjacent to the Robert E. Ward Nature Preserve using primarily state funds. Efforts continue to buy the remaining land from Chevron, using state funds, donations, or both. ==Plant life==