Under a joint venture with the same for-profit group that is reopening Pascack Valley Hospital, Hackensack University Medical Center announced Wednesday it has filed a Certificate of Need application with the state to take ownership of Mountainside Hospital, in Montclair. The joint venture with LHP Hospital Group Inc., called Montclair Health System LLC, hopes to transfer ownership of the 365-bed community hospital from Kentucky-based Merit Health Systems LLC. “The selection of this LHP-Hackensack UMC joint venture for Mountainside ensures the continued success of this hospital and its close relationship with Montclair and the surrounding communities,” said Franklyn Jenifer, chairman of the Mountainside Hospital board, in the announcement. Mountainside is home to several residency programs as well as a nursing school, and is a designated primary stroke center. It has been a for-profit hospital since Merit took ownership in 2007. This is the first time the expanding Hackensack UMC system is reaching out beyond Bergen County. “LHP is an ideal manager and operator, and Hackensack UMC a national leader in quality and innovation,” said Dr. Konstantin Walmsley, medical staff president at Mountainside, in the announcement. “With their strong histories of collaborating with physicians and commitment to investment, they will help Mountainside continue to bring the latest medical programs, technology and care to our local community.”