The physical nature of the stream (steepness, pool quality and occurrence, width, boulder size, etc.), is set by its geology and the water workings in its streambed. Generally these physical dimensions are what we think of when we recall a stream - though we might remember also its setting and how clear it was.

The chemical nature of clear, pure mountain trout streams is unseen. Its make up is generally set by the time it leaves the soil. The flow is simply conveyed, with little alteration, by stream channels. You can go to a small steep stream and all the water above that point will have flowed past by the next day. But the next day the stream continues to flow, and its pools are filled with water that was in the soil a day earlier.

During lower flows the soil does determine the chemical richness of a stream. This is the richer "base flow" in which soil elements cause some neutralization of the now acid rain. At higher flows there is also some flow that has reached the channel without long contact time or distance with the soil. It is little neutralized acid rain. Rain or snowmelt that flows over land, or over already saturated soil, is not being altered much at all. This is in fact called "quick flow."

Atmospheric acid (Acid Rain) can then enter stream channels turning them acid. Soils are saturated more often and to a greater degree in the springtime, so this would be when our streams are most acid. Unfortunately this is when trout are most sensitive to acid. This does great harm to the trout populations of our purest streams. West Virginia has suffered "fish loss," and one-fourth of its trout streams are so pure they are endangered by acid rain. We need a prompt and thorough reduction of sulfur and nitrogen emissions to protect our purest trout stream fishing heritage from permanent loss.