Here in Idaho, USA, the trees are turning, giving the landscape a most beautiful scenario of red, brown and gold, and everywhere autumn is upon us and winter not too distant. This is a far cry from the warmth of high summer, but the cold water temperatures of winter have not yet arrived with the fish farmers of the Northern Hemisphere.

That, of course, is irrelevant in this particular part of southern Idaho where the Snake River aquifer comes out of the ground at a year-round 15degC.