How healthy is the water?
Over many years, researchers at the University of Tennessee noticed that the water is becoming more acidic, especially at high elevations above 4000 feet. Even though our water looks clear and pristine, lab analysis reveals that it is contaminated with acidic sulfates and nitrates from air pollution.
Why does acidification matter? If you are a fish or insect larva, you prefer water that is neither acidic (like sour vinegar) nor basic (like smooth milk). You like neutral water with a pH around 7.0. Pure rainwater without any buffering minerals is slightly acidic—pH 5.6 or so—but minerals from rocks and soil capture this acidity and buffer it, so streams stay near-neutral. When rainwater is not just slightly acidic, but very—pH of 4.0 or even less—rocks and soil cannot buffer all of the acid. Much of it runs into streams, making them acidic as well. When stream water drops to pH 6.0—that’s 10 times more acidic than neutral 7.0 water—acid-sensitive fish and other creatures cannot survive. As the pH drops further, to 3.0-4.0 (as acidic as that sour vinegar), aquatic life cannot survive.
What’s the future for aquatic plants and animals?
But it's not all doom and gloom. There is hope to alter these trends by reducing air pollution so the predictions never come true. Through a combination of individual, community, and legal actions, we can change the way we live and, by doing so, improve water quality. The most recent check-up, from the 2008 Annual Water Quality Report, says that we can even be cautiously optimistic about at least some of the results:
We hope to continue seeing good news for Park streams. Find out more on page 3: reversing trends through research and action.