Marshes

Virginia Rail

Columbia NWR would still be wonderful without water, but with the addition of water, the refuge becomes something special.


Marshes are the most widespread wetland habitat on the refuge as a result of water originating upstream from the Columbia Basin Project and flowing down the Crab Creek "valley" to the Columbia River. Natural basins carved by Ice Age floods capture and hold these waters and, if enough soft substrate exists around the resulting pond perimeter, emergent vegetation becomes established.

Cattail and bulrush dominate the vegetation of this habitat type. The productivity and structural complexity of these and other associated plants results in a high diversity of wildlife use. A large number of species nest, breed and forage in the sometimes wide margin between open water and dry upland.

This habitat continues to evolve and change. Vast amounts of organic matter are produced each year and, because water levels vary only slightly and fire infrequently reaches these wetland margins, much of this vegetation decays slowly beneath the water's surface or along the shorelines. The water and organic matter trap soil particles, slowly filling in the pond or lake; open water slowly gives way to more emergent vegetation, while upland vegetation becomes established on the higher margins.