The largest marijuana growing operation ever uncovered in Manteca involving five separate grow houses — one backing up to Joshua Cowell School in Manteca, two in San Jose, and one each in Modesto and Elk Grove — was taken down Thursday.The bust was made possible thanks to a Manteca resident who took the time to report suspicious activity to police. That allowed officers to start an investigation that led to the seizure of 915 marijuana plants alone at the Manteca location.The investigation led by the Manteca Police Street Crimes Unit headed by Sgt. Chris Mraz initially centered on a two-story home in the 1900 block of Inderbitzen Way in the northeast section of the community. The investigation eventually tied into four other grow houses.The Manteca home had at least eight of its rooms dedicated to growing pot from seedlings to mature grows including the kitchen.