Could Someone Id This?

I found this plant on the banks of a freshwater stream while hiking in Northern California. I figured it was aquatic because the water level has decreased dramatically since the drought, and I decided to take some home. I bleached it and cleaned the whole thing off, and stuck it in my tank. It's been in there a few days and has seemed to fair pretty well. Could anyone ID it and tell me if it is possible to keep in a Brackish aquarium, as that is my current project. (The tank it's featured in it my Freshwater tank.)
 
It's the long stringy plant.
 
 

I'm not sure which plant you are asking about. The tall bladed plant looks like a Vallisneria species.