The ACE Basin is the largest estuarine preserve on the Eastern Coast that retains its original pristine quality.  In an estuary, fresh water from rivers mixes with sea water to form a complex and ever-changing environment for many varieties of plant and animal life.  In the ACE Basin the average tidal range is around eight feet, producing huge twice-daily inflows and outflows of sea and fresh water.  The rich marshlands of the Basin are scored with countless tidal creeks and rivers in addition to the main freshwater rivers that give the Basin its name.  The combination of high and low marsh, low-lying islands and myriad waterways provides a home for dolphins, alligators, minks, otters, raccoons, deer, eagles, ospreys, wood storks and many other varieties of waterfowl and other bird life.  Shrimp, crabs, oysters, clams  and fish live in the nourishing waters of the Basin and provide food for many of the other residents.

The ACE Basin also was once home to many of the rice plantations that created enormous wealth in South Carolina in the 1700's and early 1800's.  The rise and fall of the tides enabled the planters to let fresh water in and out of the diked fields as needed using only gravity and the changing water levels.  Remnants of the old fields and some still-working watergates or "rice trunks" can be seen in the Basin.  Many of the old rice fields are now planted with other grains attractive to migrating waterfowl and other species.

Two hundred years ago the deep rivers of the Basin afforded passage for ocean-going vessels that picked up and discharged cargo along the river banks but only a few vestiges of that once flourishing trade now remain.  What is left now is a marsh and sea island environment little changed from when European colonists first appeared on these shores in the early 1500's.