Complex sentence: The Bureau of Reclamation estimates the construction costs will be between $2.5 billion and $2.6 billion, while other estimates range from US $2.96 billion up to US $3.35 billion.
Split into simpler sentences: The Bureau of Reclamation estimates the construction costs will be between $2.5 billion and $2.6 billion. Other estimates range from US $2.96 billion up to US $3.35 billion.