Complex sentence: Murrieta had an all-volunteer fire department for almost 39 years, but in 1987, it became a fully-fledged municipal fire prevention district, the only one in southwestern Riverside County.
Split into simpler sentences: Murrieta had an all-volunteer fire department for almost 39 years. In 1987 it became a fully-fledged municipal fire prevention district, the only one in southwestern Riverside County.