hi, I think you may already seen in the other thread about Teal Swan, I mentioned a few asteroids relating to water:
Oceana (224), Swann (4082), Ophelia (171) (she drowned in a brook)
There' plenty of asteroids referring to rivers of course.
More prominently referring to your question:
(1009) Sirene (Italian for Siren/mermaid)
(875) Nymphe (a mythological spirit of nature imagined as a beautiful maiden inhabiting rivers, woods, or other locations.
")
(4341) Poseidon (god of the sea)
(20000) Varuna is the god of oceans
(12874) Poisson (means fish in French)
(4660) Nereus (In Greek mythology, Nereus was the eldest son of Pontus (the Sea) and Gaia (the Earth), who with Doris fathered the Nereids and Nerites, with whom Nereus lived in the Aegean Sea.)
(1318) Nerina: water nymph whoms father turned her into a river (the Nera)
(237845) Neris – nymph of Neris River
(12382) Niagara Falls
(270) Anahita (Old Persian form of the name of the Iranian goddess of the waters.)
I probably could find some more but astro.com is down for now 😆