Peter,
I spend a lot of time in that area with flyrod and camera in hand and I will vouch that the water can indeed have that green colour, even in winter. The credit River is very rich in plant and animal life and supports a very healthy trout population.
In either case, I'd love to see a series of images with the water manipulated to varying shades of green, blue, cyan and even more garish colours. I think it would make an interesting collage type images. Think Andy Worhol and various colours of Marilyn Monroe.
Ha ha, really like the idea and Peter's bluish version. I created this in Photo Elements by invoking "equalization", so the feature created and accentuated the existing colours, whites, black etc., and of course, the greens and blues. Like Joe's attitude, I viewed the result as expressing the freshness and coldness of the running water and ice. So it is not a literal or documentary image, but an impressionistic one. ...ha, ha, I am still smiling over that suggestion Joe, and may just do it! What an idea!
JMR