The Moira River begins at an unnamed lake in the more northern Tudor geographic township portion of the municipality of
Tudor and Cashel at an elevation of . It flows south into the township of
Madoc, passes through Wolf Lake at an elevation of , is crossed by
Highway 62, and takes in the right tributary Jordan River at the settlement of Bannockburn, before heading south. The river loops east then back west under the highway at Keller Bridge and continues south to the west of Eldorado. The river takes a sharp turn west, before taking in the right tributary Gawley Creek and heading south again at Malone in the municipality of
Marmora and Lake. It passes through Deloro Lake and over the Deloro Dam at Deloro at an elevation of , and is crossed by
Highway 7. The Moira then heads east, enters the township of
Stirling-Rawdon, and empties into Bend Bay on
Moira Lake at an elevation of , south of the community of
Madoc, where it takes in the left tributary Madoc Creek. The river continues east from the lake, enters the municipality of
Tweed and takes in the left tributaries
Black River and
Skootamatta River. It then heads south through the village of
Tweed, Ontario into
Stoco Lake at an elevation of , where it takes in the left tributaries
Sulphide Creek and
Clare River. The river leaves the lake via two channels, an eastern channel Moira River and the named West Channel, which enclose Sugar Island. It heads southwest, and is paralleled by
Highway 37 from Tweed all the way to Belleville. The river flows past
Chisholm's lumber Mills, through the northwest corner of the township of
Tyendinaga and enters the city of Belleville, continuing southeast. It takes in the right tributaries
Chrysal Creek and Palliser Creek, flows over the Belleville Yardmen Dam through the former Laziers Dam Site, the McLeod Dam and the Lott Dam and reaches its mouth at the
Bay of Quinte,
Lake Ontario. ==Watershed==