Footbridge downstream of junction with Frensham Pond outlet : River Wey

The water level here on the river Wey has noticeably dropped over the past 12 months.
Despite having had high levels of rainfall over the past year , the river level is consistently about half a metre lower - even after heavy rain. So much so that I've been unable to reach the water level from my usual testing spot.
I note that the banks are showing a considerable concerning erosion with the roots of trees near to the river now protruding out of the exposed bank sides.
Tree stability in this area has been undermined and I have observed many trees that had been lining the river banks have fallen over or collapsed into the river.

Further upstream of this testing spot , I observed an area of bright orange on the water surface - looking like pollution & not a natural- forming bloom. I couldn't get close enough to take a detailed picture being on the opposite side of the river with no public access but photo is included of this & another area of thick white foam.