The NASA_3Rivers_NNX11AF22G cruise consisted of watershed sampling of the Kennebec, Androscoggin, St. John Rivers in Maine, USA and New Brunswick, Canada. Water samples were collected from a nominal depth of 0.5 m and then processed as described by the accompanying documentation. Each station was visited monthly from early spring, as soon as accessible, to late fall, November. Stations were accessed by land and samples were collected by foot in the deepest water available, usually 1 to 1.5 meters in depth.