Water quality is an important indicator of ecosystem health. It is crucial to the maintenance of healthy habitat for aquatic organisms, and a source of drinking water for terrestrial wildlife and humans. In the San Francisco Bay Area, water quality affects threatened and endangered species, such as the California freshwater shrimp, coho salmon, steelhead trout, and the California red-legged frog.
Water quality in a national park may reflect activities taking place upstream of the park’s surface waters as well as within the park itself. Road construction, recreational activities, livestock and agriculture, sewage leaks, deposition from atmospheric pollutants, and many other factors can impact water quality. Parks in the San Francisco Bay Area are particularly susceptible to these impacts because of their close proximity to a major urban center.