Essin
The historical "Ekonomiska kartan" gives the name as "Arbogaån (Bottenån)", so both names are documented to be in use. Ekonomiska kartan is not consistent with the name of the river upstream though, Arbogaån disappears and reappears several times. If Bottenån is most used locally it should have priority to name=, but Arbogaån can be set as alt_name=.