Complex sentence: Lake Elsinore is the largest natural freshwater lake in Southern California and with its own 750 sq mi (1,900 km2) watershed is situated at the lowest point within the San Jacinto River watershed of at the terminus of the San Jacinto River.
Split into simpler sentences: Lake Elsinore is the largest natural freshwater lake in Southern California. With its own 750-mi 2 (1,900-km 2) watershed, it is situated at the lowest point within the San Jacinto River watershed of, at the terminus of the San Jacinto River.