Complex sentence: The lake was formed from the Saratoga Bend in the Missouri River, which was the impetus for the creation of the town of Saratoga, Nebraska Territory, a short mile from the river.
Split into simpler sentences: The lake was formed from the Saratoga Bend in the Missouri River. The Saratoga Bend was the impetus for the creation of the town of Saratoga, Nebraska Territory, a short mile from the river.