Editing North Cascades National Park (section)

=== Air and water quality ===
[[File:Paul Bunyans Stump 25870.JPG|thumb|Air quality in North Cascades National Park is generally considered good and aside from some reduced clarity due to haze, even distant peaks are easily seen most days.|alt=A distant mountain range above a diagonal slope of forest.]]
While North Cascades National Park is in a remote region for the most part, the prevailing westerly winds bring various pollutants into the park from the industrialized region around Puget Sound and the [[Fraser Valley|Fraser River Valley]] of British Columbia. These pollutants deposit onto plants and glaciers and are then carried by rainfall or ice melt and dispersed into rivers and lakes.<ref>{{cite web|title=Air Quality|url=https://www.nps.gov/noca/learn/nature/airquality.htm|publisher=National Park Service|access-date=March 27, 2018}}</ref> The industrialized regions around Puget Sound and the Fraser River Valley have had a more noticeable negative impact on water and air quality than at [[Mount Rainier National Park]] well to the south due to the prevailing winds. Lakes at higher elevations show a higher level of acidity due to this phenomenon; the current and long-term impact on the ecosystem of the park has not yet been fully assessed.<ref name="sulfur">{{cite web|title=Air Pollution Impacts|url=https://www.nature.nps.gov/air/permits/aris/noca/impacts.cfm?tab=0#TabbedPanels1|publisher=National Park Service|access-date=March 27, 2018}}</ref>

[[Mercury (element)|Mercury]] and toxins from pesticides have been detected in the park, as has [[ozone]]; these have not been demonstrated to be at sufficient concentrations to greatly impact the ecosystem. Sulfur, [[nitrogen dioxide]] and ozone from factories and automobile emissions as well as increased dust and fine particulates from sources such as farming and construction are dispersed into the atmosphere, reducing long-range visibility.<ref>{{cite web|title=More on Air Quality|url=https://www.nps.gov/noca/learn/nature/airquality2.htm|publisher=National Park Service|access-date=June 28, 2018}}</ref> Visibilities of up to {{convert|150|mi|abbr=on}} have been reduced to less than {{convert|50|mi|abbr=on}} on the worst days due to the increased haze.<ref name="sulfur" />

Climate change will impact the temperatures of high altitude lakes and streams, which in turn will have an effect on the fish that can thrive in these waters. Retreating glaciers reduce the amount of glacial ice melt available in warmer months that kept streams and lakes cold, even in late summer.<ref name="riedel1" />