Threats to Water Resources
Air Pollution and Contaminants
By far, the single biggest threat to the parks’ water is air pollution. Air pollution adds acidic deposition, nutrients, and other contaminants to the parks’ waters. Acidic deposition is most acute as episodic events during early snowmelt and during late-summer and fall thunderstorms. Fortunately, at current levels, the parks’ waters are not showing chronic acidification, but this could change because the waters are poorly buffered and therefore limited in their capacity to neutralize acids. Because the parks’ waters are naturally low in nutrients, the addition of airborne nitrates and ammonia is likely to be causing some level of change to the natural system.
Alteration of Fire Regime
The alteration of the natural fire regime by over a century of fire exclusion through grazing activity and fire suppression is another stressor to the parks’ waters. Fire affects the quantity of water in streams and its water chemistry. Sediment transport rates are different in burned and unburned watersheds. Fire affects nutrients, buffering capacity, water temperature, and other water characteristics.