Rivers carrying tea-colored water entered Hannah Bay and Rupert Bay in late September 2026, staining the southern reaches of James Bay brown. The color came from dissolved organic matter that leaches from decaying leaves, roots, bark and soil as water moves through boreal forests and peat bogs. NASA's Landsat 9 Operational Land Imager captured the scene on September 27, 2026, showing the Moose, Nottaway and Harricanaw rivers spilling brown plumes across mudflats where they met the darker blue waters of James Bay.

The brown hue results from colored dissolved organic matter absorbing blue and ultraviolet light, a natural process also seen in tea. Fine mud particles from the shallow, sloping bathymetry of the bay's southern end combine with suspended sediment stirred up by tides and river currents, creating the lighter brown plumes visible near shore. Vegetation patterns on the mudflats reflect moisture differences, with dense forest appearing dark green and adjacent peat bogs showing lighter green tones.

Beavers have shaped this landscape for centuries. The Cree name pahtaaunaakun, meaning "color of singed beaver," references both the brown water and the animal's historical role. Cree hunters have harvested beavers for meat and pelts for millennia, while European traders arrived in Rupert Bay in the 1660s to exploit the fur trade, eventually establishing Hudson's Bay Company posts. Cree oral tradition includes stories of giant beings and mythical beavers, such as one recorded by anthropologist Alanson Skinner that explains the origin of Stag Rock in the Nottaway River mouth.

Historically, beaver populations faced decline due to overtrapping, prompting early conservation efforts. In the 1830s and again in the 1930s, Hudson's Bay Company collaborated with Cree communities to create protected beaver preserves on islands like Charlton Island, where predator removal and translocated breeding pairs led to population recovery.

The brown water flow is a seasonal phenomenon tied to autumn runoff, when organic material from decomposing vegetation enters waterways. This natural process continues to shape the ecology of the James Bay Lowlands, where postglacial rebound gradually lifts the land while rivers deposit fine sediments that build and reshape mudflats over time.