Complex sentence: "Memorial," as it is more commonly known as within Sonoma County, is part of the St. Joseph Health System and serves a population of approximately 500,000 people living in Sonoma County.
Split into simpler sentences: Memorial, as it is more commonly known as within Sonoma County, which is part of the St. Joseph Health System. Memorial Hospital serves a population of approximately 500,000 people living in Sonoma County.