The lower estuary is defined by large islands.
 The estuary is split by Westport Island.
 The channel east of Westport Island is considered the Sheepscot River, while the western channel is identified as the Back River.
 The Back River is crossed in Hockomock Bay by a tidal channel identified as the Sasanoa River.
 The Sasanoa River connects the Kennebec River estuary at Woolwich with the Sheepscot River estuary between Westport Island and Georgetown Island.
 Georgetown Island forms the west side of the mouth of Sheepscot Bay and the east side of the mouth of the Kennebec River estuary.
 The Back River reaches the Kennebec River on the west side of Georgetown Island.
 Arrowsic Island forms the east side of the Kennebec River estuary between the Sasanoa River and the Back River.
 Maine State Route 144 bridges the Back River from Wiscasset to Westport Island.
 Maine State Route 127 bridges the Sasanoa River from Woolwich to Arrowsic Island and the Back River from Arrowsic Island to Georgetown Island.
The lower estuary is defined by large islands.  The estuary is split by Westport Island.  The channel east of Westport Island is considered the Sheepscot River, while the western channel is identified as the Back River.  The Back River is crossed in Hockomock Bay by a tidal channel identified as the Sasanoa River.  The Sasanoa River connects the Kennebec River estuary at Woolwich with the Sheepscot River estuary between Westport Island and Georgetown Island.  Georgetown Island forms the west side of the mouth of Sheepscot Bay and the east side of the mouth of the Kennebec River estuary.  The Back River reaches the Kennebec River on the west side of Georgetown Island.  Arrowsic Island forms the east side of the Kennebec River estuary between the Sasanoa River and the Back River.  Maine State Route 144 bridges the Back River from Wiscasset to Westport Island.  Maine State Route 127 bridges the Sasanoa River from Woolwich to Arrowsic Island and the Back River from Arrowsic Island to Georgetown Island.
Sheepscot River