Abstract in Green and Orange.
The emphasis in this version is on the vegetation, which certainly looks more like moss than algae.
Rusty sludge from a drainpipe that empties across the narrow strip of gravel under the bridge.
Additional images of this same feature are at: http://smu.gs/QDzzPa and http://smu.gs/QDzBqc
Huron River near the boundary between Gallup Park and Parker Mill Park, Ann Arbor, Michigan
October 23, 2010