I've spent over a decade telling everyone I know that this beautiful member of the Balsaminaceae of plants was an invasive, exotic species from Asia and I was completely wrong. I recently discovered that it is natively found that is found near wetlands and streams in all over North America except the arid American Southwest, Wyoming, Montana and Alaska.
What I wasn't wrong about is it's natural characteristic as a cure for poison ivy (which I suffer greatly from every time I come into contact with it). Sap from the crushed leaves and stems if applied soon after contact can negate or greatly reduce the rash from contact with poison ivy. Just be wary of the berries produced after the flowers are pollinated as they can be quite toxic to humans, especially children.
This one was one of thousands found growing on the edges of Soos Creek in Southern King County, in Kent, Washington.