Sewage fungus
Sewage fungus (also known as undesirable river biofilms, URBs) is a polymicrobial biofilm (a microbial mat) that proliferates in saprobic rivers and has been frequently used as a bioindicator of organic river pollution for the past century. Its presence has been strongly associated with discharges of untreated or inadequately treated sewage, yet its presence extends beyond these areas, with contributors including airport de-ice fluid runoff, papermill effluents, and agricultural runoff.