Complex sentence: The Erie Canal allows for water navigation to the Great Lakes, and the Champlain Canal connects the Hudson River to Lake Champlain, the Richelieu River/Chambly Canal then connect Lake Champlain to the St. Lawrence Seaway and Montreal.
Split into simpler sentences: The Erie Canal allows for water navigation to the Great Lakes, and the Champlain Canal connects the Hudson River to Lake Champlain. The Richelieu River/Chambly Canal then connects Lake Champlain to the St. Lawrence Seaway and Montreal.