Managed Wetlands

Wilson's Snipe

While nature rarely, if ever, needs help left to its own devices, it can occasionally benefit from augmentation. On Columbia NWR, that comes in the form of managed wetlands, or as the U.S. Fish & Wildlife Service calls them, "Moist Soil Management Units."


The refuge has constructed 30 marsh units divided by dikes; these units are intensively managed temporary wetlands with water control structures to allow water to flow in and out. Part of the year, the marsh units are dry to allow the growth of important wildlife plants. The areas are tilled periodically to set back succession, which tends to produce the most seed for waterfowl and other wildlife, and sometimes planted with millet, barnyardgrass (Echinochloa crusgalli), or smartweed (Polygonum persicaria).

In the fall, after the plants mature, the areas are flooded to make food available to waterfowl. Even without planting, native and exotic seed-producing annuals and other plants would reproduce "naturally" and provide wildlife food for select species. Desirable self-seeding plants include witchgrass (Panicum capillare), beggar's tick (Bidens frondosa), smartweeds and barnyardgrass. However, many undesirable plants also seed themselves, such as reed canarygrass (Phalaris arundinacea), bulrush, knotweed (Polygonum arenastrum) and rushes. During seasonal flooding in spring, these managed marshes host numerous waterfowl and shorebird species.