stagnant water, thickets of algae, mayflies larvae

stagnant reservoir dense seaweed thickets algae mayflies hatched shells larvae remained macrophytes pondweed potamogeton pondgrass water spike weed dayfly ephemeron may fly ephemera mayfly creature day backwater banks bog bogginess bogging boggingup eutrophication freshwater soldier grasses covered headwaters helium inundation logging marsh minor rivers northern osier bed overgrowing river hydrology short sloughing small stratiotes aloides swamp formation swamping vegetal invasion waterlogging weediness waters