Erigeron maniopotamicus is a rare species of flowering plant in the family Asteraceae known by the common name Mad River fleabane.

[2] It is endemic to northwestern California, where it is known from only nineteen locations in Humboldt and Trinity Counties.

[4] Erigeron maniopotamicus was described to science in 2004 from a type specimen collected on Board Camp Mountain in Humboldt County in California.

"[4] Erigeron maniopotamicus is a perennial herb growing from a taproot and caudex unit.

Each head has a lining of pointed phyllaries which are green with orange midnerves.