Complex sentence: There have only been two uses of the gates thus far; the first occurred in 2002 during a major flood in the region, and the second in 2003, due to anticipation of the rising river getting higher.
Split into simpler sentences: There have only been two uses of the gates thus far, the first occurred in 2002 during a major flood in the region. And the second occurred in 2003, due to anticipation of the rising river getting higher.