Simplify the following text for a Grade 4 native English-speaking person.
Original: The water that flows out of Lake Huron goes through a river that flows past Detroit , Michigan .
Simplified: It drains into the St. Marys River at Sault Ste . Marie which then flows southward into Lake Huron . The water then flows south to the St. Clair River , at Port Huron , Michigan and Sarnia , Ontario .