Riverine lakes, also referred to as oxbow lakes, occur naturally within the floodplains of large rivers. They are periodically connected to rivers and streams, therefore behave as drainage systems when water levels are high and have direct connections to flowing waters and like lakes when water levels are low, and they are temporarily isolated. Oxbow lakes are a special type of floodplain lake that form when a wide meander from the main stem of a river is cut off, creating a free-standing body of water. Common plants include American white water-lily (Nymphaea odorata), bull-head pond-lily (Nuphar variegata), and various pondweeds (Potamogeton spp.) species. The more pristine oxbows harbor bladderworts (Utricularia spp.) and water star-grass (Heteranthera dubia). Highly eutrophic systems can become choked with free-floating plants like duckweeds (Lemna spp.), water-meal (Wolffia spp.), and filamentous algae. While bluegill and largemouth bass are common associates at most riverine lakes and ponds, some fish associates reflect the amount of groundwater input. Grass pickerel is associated with significant groundwater input, whereas central mudminnow and golden shiner are associated with lakes that have little groundwater influence.
