Decker Cove in Magnolia TX: Is This New Long Lake Community Worth Touring? Decker Cove is one of Magnolia’s newest new-construction communities, and it is worth watching if you want a new home near Tomball, Magnolia, Highway 249, and FM 2920 without jumping into one of the giant master-planned communities farther north. The community is being built by Long Lake Home Builders and is located at...