I am an Ecologist with Adopt-A-Stream Foundation, a non-profit stream restoration organization. I am creating a planting plan for a golf course in Snohomish County. My constraints: Low-growing native shrubs with extensive root systems to help filter out the golf course irrigation water before it enters the stream. Willow would be an obvious choice, but it would grow too tall and out of control. I was looking at such species as Snowberry (Symphoricarpos), Nootka Rose (Rosa nutkana), Salmonberry (Rubus spectabilis), etc. It would have to be a FAC+ (streams and wetlands). Any thoughts?
FAC+ is a wetland indicator status term meaning “Facultative,” i.e., more likely to occur in wetlands but also found in non-wetlands.
I found a list in Restoring Wetlands in Washington Publ#93-17 and picked out the FAC-identified ones, eliminating all the tall trees and shrubs. Symphoricarpos (Snowberry) would be a good option, but Rosa nutkana (Nootka Rose) and Rubus spectabilis (Salmonberry) get too big for your purposes. A different rose I could recommend is Rosa gymnocarpa (Baldhip Rose). Many of the following recommendations are grasses of one sort or another. (See the USDA Wetland Indicator status definitions.)
Allium geyeri (non-native) FACU
Athyrium filix femina FAC
Carex aperta (non-native) FACW
Carex stipata FACW
Deschampsia caespitosa FACW
Juncus effusus and ensifolius FACW
Ledum glandulosum FACW
Sambucus racemosa var. melanocarpa FACU
Spirea douglasii FACW
You might also try the Snohomish County Conservation District website.