The Nigoglia (Lombard: Nigoeuja or Nigòja; Piedmontese: Nigheuja) is a short Italian river whose source is at the northern end of Lake Orta, of which it is the sole outflow. Its course of less than 2 kilometres passes in a northerly direction through the town of Omegna and into the Strona.

As a rule, the outflows of Italy's major subalpine lakes run in a southerly direction, down to the plains of the Po Valley. The Nigoglia is the exception, seeming to run "upwards" towards the high Alps.