Mossies need stagnant, or at least still water. At the nymph stage (caterpillar) of their life cycle, the nymph hangs from the miniscus (water suface tension) and breathe through their arse. The body trawles for passing food particles. Moving water won’t have the needed surface tension.
I studied this, among a lot of other stuff, a long time ago. When I lived in Cyprus, they came round every week or so with smokers. I think the smoke was parafin. Two guys carrying these machines, blowing smoke everywhere, especially into drain covers and anywhere water could collect. The parafin settles on the water, preventing the mossie nymphs from breathing. Fire buckets and the like had to be emptied and refilled at least once a week, daily was preferred.