Complex sentence: In 1965, the Soviet government built Plavinas Hydro Power Plant in the town of Aizkraukle, which flooded the entire length of the Daugava to Plavinas.
Split into simpler sentences: In 1965, the Soviet government built Plavinas Hydro Power Plant in the town of Aizkraukle. The reservoir flooded the entire length of the Daugava to Plavinas.