An environmental group that has been keeping tabs on the SouthField development at the former South Weymouth Naval Air Station will report on its latest findings at a public forum scheduled for March 13 at the Tufts Library. Advocates for Rockland, Abington, Weymouth, and Hingham also will discuss the implications of the developer’s proposed governance changes for the site, which includes parts of the four communities. “As a group we’ve been most interested in the contamination there and the environmental impacts” of the development, said Dominic Galluzzo. “But lately it’s become such a political football that we’ve been doing our best to fill in the blanks” with information. The meeting will start at 7 and end at 8:30 p.m., he said. Tufts Library is located at 46 Broad St.