Complex sentence: When completed, the Tenn-Tom waterway's total cost, including non-federal costs, was $1.992 billion, which led some political and economic commentators derided the Tenn-Tom waterway as pork-barrel politics at its worst.
Split into simpler sentences: When completed, the Tenn-Tom waterway's total cost, including non-federal costs, was $1.992 billion. Given these staggering costs, before the project was completed, some political and economic commentators derided the Tenn-Tom waterway as pork-barrel politics at its worst.