Simulated heads in the glacial drift aquifer in response to ice loading during the Port Huron advance, approximately 13,000 years before present.

  • Stippled light blue shows extent of Port Huron ice.
  • Solid blue shows extent of proglacial Lake Saginaw regulated by 695' Glacial Grand outlet.
  • Solid yellow shows the Glacial Grand drainage from proglacial Lake Saginaw (695') to Glacial Lake Chicago (640') in the southern basin of modern Lake Michigan.
  • Groundwater flow would have been downward from heads (greater than 2000 feet) along the axis of Saginaw Bay and upward into proglacial Lake Saginaw (with 695' heads).