Along streams it's best to have trees and shrubs to help hold the streambanks, to slow down the floodwaters, to provide shade to the stream, and to create cover in the stream from the roots, branches, and fallen trees. In other words, a forested riparian buffer.
Forested riparian buffers not only conserve the streams, they are heavily used by deer.
To find out what trees and shrubs are likely to grow along your stream, do a long walk along the stream and write down what tree and shrub species you see. If you aren't good at IDing them, take along someone who can.
Wack the knotweed. Plant those tree species. Continue wacking the knotweed, so that it doesn't out-compete the trees.
Pin oaks grow well along streams in many places and produce acorns.
Dogwood is a shrub that grows well along streams in many places. It grows thick and might be able to out-compete the knotweed.