Well, at least it is not an ecological disaster. Tannin is natural, I guess, even though maybe nature's detritus.
And the photo seems pleasingly slightly underexposed, dramatizing the shadows. (Was that two stops extra you exposed at really one stop under, due to the age, or was this printed a bit darker?) - David Lyga
Technical issues aside, the "tannin tone" is interesting and effective.
Tannin is also critical to the flavor of many red wines, sometimes only faintly and sometimes too powerfully (considered a "flaw"). I think it would be worthwhile to pursue this "tannin stained" water into more images, making that a partial theme in itself.
@David Lyga@jtk re. exposure. Shooting at 50ISO was a wild guess. The roll came to me in a bag with some other gear I bought, so I have no idea how it has been stored for the last decade+ (could have been frozen, refrigerated, or sitting in a hot car!).
Tannin is very common in the lakes and streams or Tasmania, and is generally picked up as water passes through large areas of peaty moorland, heath, tea-tree and Eucalyptus scrub. It’s a very characteristic element of the landscape - rather than getting crystal clear mountain streams, we get inky black wild rivers I agree, a photographic study would be an interesting project!