Precipitation can dissolve gases in the air to form acids. Dissolved carbon dioxide in rain and snow forms a weak acid with a pH between 5 and 6. When rain and melted snow soak into the soils, this acid dissolves minerals which raise the pH of the water running off into a stream.

pH in East Canyon Creek varies between 7 and 8.5. The values fluctuate naturally for a number of reasons, including the mix of groundwater and direct rainfall or snow melt and the amount of plant activity in the stream.