Faraway Fly Fishing

On a scale of 0 to 14 pH, a value of 0 is the most acidic and 14 the most basic.

The rain usually has a pH between 5 and 6.5. It is acidic because it has dissolved carbon dioxide and air pollutants such as sulfur dioxide and nitrogen oxides. If the rain water flows over soil containing minerals, the pH usually increases. Bicarbonate ions, HCO-322-HCO

As a result, streams and lakes are usually basic, with pH values between 7 and 8, sometimes as high as 8.5.
The measurement of pH of a body of water is very important as an indication of water quality due to the sensitivity of aquatic organisms to the pH of their environment. Small changes in pH can endanger many types of plants and animals, such as trout and various nymphs can only survive in waters with pH values between 7 and 9. If the pH of the water in which they live is outside this range may not survive or reproduce.

Table 1: pH levels and effects on aquatic life.

pH          Effect

3.0 – 3.5 Fish are unlikely to survive over a few hours in this range, though you can find some plants and invertebrates to pH levels as low as these.

3.5 – 4.0 Is known to be lethal to salmonids.

4.0 – 4.5 Absent all fish, frogs and many insects.

4.5 – 5.0 Many insects away. Most fish eggs will not hatch.

5.0 – 5.5 Bacteria that lives on the bottom of water bodies (decomposers) begin to die. Leaf litter and debris begin to accumulate, trapping nutrients and interrupting chemical cycles. The plankton starts to disappear. Snails and clams absent. Carpets of fungi begin to replace the bacteria in the substrate.
Metals (aluminum, lead) normally trapped in sediments are released into water acidified forms toxic to aquatic life.

6.0 – 6.5 Freshwater shrimp absent. Unlikely to be directly harmful to fish unless the level of free carbon dioxide is high (in excess of 100 mg / L)

6.5 – 8.2 Optimal for most organisms.

8.2 – 9.0 Unlikely to be harmful to fish, but indirect effects occur at this level due to chemical changes in the water.
9.0 – 10.5 Likely to be harmful to salmonids and perch if present for long periods.

10.5 – 11.0 To rapidly lethal for salmonids. Prolonged exposure is lethal to carp and perch.

11.0 – 11.5 Rapidly lethal to all species of fish.

This occurs under normal conditions, it is important to know how this particular type of ash that has fallen affects on our lakes, streams and how is altering the pH of the environment.

What kind of composition has the fallen ash?
What you can find in INVAP and CONEA preliminary work  http://organismos.chubut.gov.ar/a mbiente/files/2011/06/Informe-Cenizas-Puyehue1.-INVAP.pdf who express the composition of falling sand is mostly silica, stone bone Pomes, with low concentrations of substances harmful to health and the agencies that come into contact with it.
With data from pH of 5.2, whereupon the pH of the water level could drop from 7 or 8 to 6, where as the mass amount of water relative to the amount of ash fall is considerably less and that there would be a  important solution, so the pH could fall below 6 (which is almost impossible).

Conclusion
I don’t think the ash due their composition will affect the life of the trout, it is likely to affect the benthic organisms (insects) and part of the spawning, is likely to affect or diminish the effectiveness of this. We won’t be able to see the effects the next  season, we would be able see the consequences in a couple of years or maybe there won’t be any negative consequences. We all hope fishing in the area keeps on giving us rewards like every year.

Thanks to Lucho Bacci for the great article! We are looking forward for more info about this.