The river and banks

Like everything on this adventure, I've never modeled a river, I've seen plenty on the internet showing how to make a small meandering streams, and these look fabulous, I'm trying to make a deep river.

The shot above is upstream from where I'm trying to recreate, but I cannot get access to the actual spot, quite wide, not too deep, loamy banks with some dead flora blocking the way, up closer towards the Murray Goulburn factory, one section maintains this, while directly behind the the factory, the bank has been strengthened with lots of rock and spoil pushed into the river forming a kind of wall.

What I've done so far, is mixed some Vogel (tan/brown colour) water based paint, with some PVA glue, stirred in a mix of small Talus and Ballast to create thick "rocky ooze".
I've painted this as the base of the river, and built the rock/spoil wall by molding a bunch of plaster rocks using a Woodland Scenics mold, I attached them to the river bank, waited a few weeks and then chiseled them out, leaving a mess of small and large bits of rubble, these were cemented into place and pigmented to something I hope looks realistic, i think it's a little too dark, but I haven't "set" the colours yet, so I'll be toning it down slightly.

Next on my agenda, is to find some suitable twigs to act as dead trees, touch up the river banks and colour variety and pour some sort of water in place.  I'm thinking Envirotex, but if anyone out there who may read this knows of a better product, I'm all ears.