two early examples of scientifically designed bioswales for large scale applications are found in the western us. in 1996 for willamette river park in portland, oregon a total of 2330 lineal feet of bioswale was designed and installed to capture and prevent pollutant runoff from entering the willamette river. intermittent check dams were installed to further abet silt capture, which reduced by 50% suspended solids entering the river system.