Watershed protections is important because this is the land through which water is transported on its way to rivers, lakes, wetlands, and ultimately the ocean. As water moves throughout the watershed and the area from which water is collected and transported to the system, rivers typically increase in size. However, while the upper reaches of the watershed may have less overall water, they typically contain the majority of river miles within a watershed and thus comprise of a vast and rich ecosystems that many animals, physical processes, and vegetation rely upon. However, these miles of rivers are vulnerable to water pollution and other alterations.
Historically, land adjacent to rivers and lakes in upper reaches of the watershed have been popular sites for deforestation, agriculture and irrigation, and development and given the sparse population and steeper slopes has made it popular for dams.
Dams in the watersheds provide many cities green energy, water storage, and recreation, and thus have immense economic value. However, today’s dams have inundated upstream river and dewatered streams downstream, caused the reduction of sediment movement and flood frequency that prevents the re-creation of valuable habitats downstream, and can alter the water temperature, discharges, and path that fish depend on for breeding, development, and migration. Further, due to the trapping and storing of water, water quality can degrade due to higher and lower temperatures than the surrounding streams, stagnation and nutrients from upstream or nearby agriculture can increase algae blooms.
Agriculture in many areas has cleared the once thriving ecosystems of floodplains, wetlands, and forests and replaced these with crops. The biggest concerns are that the replaced wild lands with crops or ranching not only add more pollutants to the waterways, but the lands ability to naturally store and filter water and pollutants is also reduced. This comes as agriculture lands typically have higher surface water runoff and the soils do not store nutrients/pollutants as well (and are often tilled bringing pollutants to the surface). Further, agriculture requires more water and energy than the previous land, and in severe cases, such land transformation can cause increases in local temperatures, and reductions in precipitation. All of this as well as compromises the water quality and quantity available to downstream users and ecosystems.
Abandoned mines also are of high concern in watersheds. While these mines may have been abandoned a few years ago or many centuries ago, the pollutants cause the same health concerns and ecosystem damages. In England and Wales, 9% of the rivers are failing to meet the Water Framework Directive's targets due to abandoned mines (Abandoned mines and the water environment). In the U.S. there are an estimated 500,000 abandoned mines, and in Colorado, there are 7,300 abandoned mines, which at least 230 are known to significantly affect water quality through heavy metal contamination (The Denver Post). Abandoned mines and other industrial spills release pollutants like mercury, cyanide, zinc, lead, copper, and cadmium cause significant damage. A recent example is the August 2015 Animas Mine Disaster in Colorado, which released large amounts of arsenic, lead, copper, and cadmium. These chemicals have both short and long-term effects on animals both from direct and indirect (e.g. food chain) exposure.