A giant Southern California water district that could decide whether to invest in the Delta tunnels as soon as September has released the first of three “white papers” which are expected to address some unresolved issues. Among other things, this latest document from the Metropolitan Water District of Southern California describes the new joint powers authority that might be formed to oversee construction of the 40-foot-wide tunnels. The tunnels are a state project, but the Department of Water Resources is busy with the reconstruction of the Oroville Dam spillway after this year’s flooding, the white paper notes.