Water resources along the AT include lakes, ponds, streams, rivers, seeps, springs, wells, and wetlands. The form, structure, and occurrence of these water resources vary considerably and their characteristics and occurrence depend on the geology, climate, and the terrestrial ecological systems found in any particular area. Water resources serve many uses along the AT, such as a source of drinking water for hikers, visitors, and wildlife, providing recreational, scenic and esthetic value, habitat for plants and animals, and a source of water for downstream uses (such as public water supplies, fisheries, hydropower generation).
The AT crosses about 1,700 streams and 100 rivers from Georgia to Maine. The great majority of these crossings are intermittent (zero order), first and second order streams (having a width of less than 5 meters) (source M. Robinson, ATC, 2006). These lower order streams are representative of the forested mountainous and higher elevation terrain that characterizes most of the AT region. It is the zero, first and second order streams that are of most concern for monitoring and management (we will term these high elevation tributaries). Higher order streams and rivers are typically found at lower elevations and bottom lands and are reflective of larger drainage basins, and multiple contributing land uses.
There are 75 lakes and ponds along the AT (M. Robinson, ATC, 2006). These lakes and ponds (collectively called ponds) are a combination of natural and man-made waterbodies; natural ponds are thought to be more common from New Jersey northward on the Trail. These natural ponds tend to be small, in high elevation catchments, or in lowlands between ridges and mountains. Ponds often serve as important recreational areas, whether for swimming, a water supply source, or the site of camping/shelters for overnight usage. The natural ponds provide habitat frequented by wildlife such as mink, bear, and moose; and larger ponds also may serve as loon nesting sites. Human-made ponds are found along the length of the AT and were generally constructed for water supply, agricultural, and hydropower purposes.