Nomenclature/tagging: differentiation between a stream and a river

I’m tracing a watercourse which varies in width, depending on the place and season, from 1 metre to approx. 8 metres. Its depth varies. Because it runs over karst its depth varies between 50cm and, where it runs over a sinkhole, 10+ metres. At some times of the year it would be navigable (e.g. with a rubber dinghy) and at other seasons not. I don’t know whether to call it a river or a stream. Do I simply decide arbitrarily or are there guidelines on this (e.g. “If the banks are more than 20 metres apart at the narrowest point it’s a river”) ?

The convention I heard of and use myself: If a pedestrian can cross it without a bridge and without getting his feet wet, it’s a stream. Anything bigger is a river.

Neat definition. Very practical. Put in other words, if a pedestrian can jump across it or use stepping stones it’s a stream. Thanks.