A Journey into Learning at Oak Grove Union School District, Sonoma County, CA. A Journey into Learning at Oak Grove Union School District, Sonoma County, CA. Nestled in the heartland of Sonoma County, California, the Oak Grove Union School District (OGUSD) is a beacon of educational brilliance. This institution is not just a school district; it is a vibrant community of learners, educators, and parents striving together to shape the future leaders of tomorrow.