Brush/Weed control along streams/creeks?

[Four Paws]

I have about 500' of stream that runs through my property. It doesn't flow fast or hard enough to keep itself cleaned out - therefore, every year in the fall, I go through and clean the brush and weeds by hand. Most of it comes in 2 forms; tubular weeds that form a blanket across/through the water - they grow dense and have a leaf similar to that of a jade tree houseplant.
The other weeds are more brushy - they start out with a soft stem, and then grow more woodlike as the plant matures - they have vine-like tendencies, but eventually grow up to be more of a nuisance than the stuff that grows like a blanket. Either way, I am looking for a herbicide that will take care of them and is relatively safe to use around watersheds. I can provide pictures if you guys want to try and identify them...just let me know. I would appreciate any/all help deciding on appropriate method to control the brush - want to keep the banks managable and the water way open for visual enjoyment.

Thanks, Josh

 

[Octane]

Could you maybe lay some gravel or sand on the bed of the creek to prevent the vegetation from growing?
Im thinking that with even a slow-moving creek that any herbicide is going to be a no-no.

 

[Garfield]

brush cutter

the kind they use to mow the banks on a hydraulic arm. I don't know where you get one of these but i assume they are for rent somewhere.

 

[RatchetJaw]

simple

your section of stream has to much sunshine plant some alders or some other shade trees along the edge of the bank also the first one sounds alot like duck weed not sure go ahead and post the photos as for the short term keep pulling and dont let fish n game catch ya doing it big fines for disturbing reprarian zones and i would advise against anything with hydraulics the oil slick will lead them right to you. if your that hard up a rowboat and a trolling motor set shallow could help to roll the weeds up and pull them out.