Complex sentence: Although the dam was never built, 72,000 acres (291 km²) of land were acquired by condemnation and eminent domain--the means of which caused the controversy by inciting environmental protesters and embittering local residents displaced by the project's preparations when their property was condemned.
Split into simpler sentences: Although the dam was never built, 72,000 acres (291 km²) of land were acquired by condemnation and eminent domain. This inciting environmental protesters and embittering local residents displaced by the project's preparations when their property was condemned.