Complex sentence: The river flows west, past Sedro-Woolley and Mount Vernon, and at the former site of Skagit City it diverges into two forks, a north and south fork, forming Fir Island.
Split into simpler sentences: The river flows west, past Sedro-Woolley and Mount Vernon. At the former site of Skagit City, it diverges into two forks, a north and south fork, forming Fir Island.