OK I get it...I think...
A rill by definition could not contain trout.
A rivulet might.
But...C is ...redundant.
Oh, I could go on alright. A meager sampling:
E, F, G,…:
…, river, stream, creek, brook, beck, headwater, reach, spring, seep, feed, tributary, stem, nursery water, flow, current, spate, torrent, cascade, falls, riffle, pool, cut, pocket, basin, head, tail, broken, flat, slick, ‘nervous’ water, ... and on and on….
Let there be no shortage of creative descriptors. But, agreed: if they are used more than once (not tongue in cheek), they should at least be accurate.
Comprende.