When rivers drain into oceans through narrow mouths, hydraulic
forces squeeze the river water into buoyant plumes that are
clearly visible in satellite images. Worldwide, river plumes not
only disperse freshwater, sediments, and nutrients but also
spread pollutants and organisms from estuaries into the open
ocean. In the United States the Columbia River, the largest
river by volume draining into the Pacific Ocean from North
America, generates a plume at its mouth that transports juvenile
salmon and other fish into the ocean. Clearly, the behavior and
spread of river plumes, such as the Columbia River plume, affect
the nations fishing industry as well as the global economy. A
delicate balance between density and velocity controls turbulent
mixing within the plume and how far river plumes extend into the
deep ocean. On the other hand, coastal winds and currents affect
the shape and orientation of the plumes. However, current
understanding of momentum changes along a river plume is limited
by poorly constrained