In establishing critical levels of acid deposition and lake, stream, and soil acidification, the department of ecology shall consider:

(1) Current acid deposition and lake, stream, and soil acidification levels;

(2) Changes in acid deposition and lake, stream, and soil acidification levels;

(3) Effects of acid deposition and lake, stream, and soil acidification on the environment; and

(4) The need to prevent environmental degradation.