The public advocacy for undeveloped open space pressure was very strong, and development was halted further by new groundwater tests showing migrating contamination of the aquifer with toxic substances from the adjacent Rocketdyne Santa Susana Field Laboratory (SSFL) experimental Nuclear Reactor and Rocket Engine Test Facility. The Santa Monica Mountains Conservancy and the State of California purchased the land for public regional park. The Lasky Movie Ranch is now part of the very large Upper Las Virgenes Canyon Open Space Preserve, with various trails to the Lasky Mesa locale.