Outside of the Smithsonian’s National Museum of the American Indian, they have a fabulous water feature that is part of the entire outdoor environment. It’s supposed to be much like it used to be when the Native Americans populated the land around Washington DC. From their website:
Culturally significant to many tribes, wetlands are rich, biologically diverse environments. The museum’s diverse wetlands area—and the ducks, squirrels, and dragonflies that make it their home—represent the original Chesapeake Bay environment prior to European settlement. Chesapeake means “Great Shellfish Bay” in the Algonquian language. River birch, swamp milkweed, pond lilies, silky willow, and wild rice abounded in the dense marshes, as they do in the museum’s natural habitat.
If you get a chance to see it next time your in or near DC, I would highly recommend it.