Although significant strides have been made in reducing the impacts of discrete pollutant sources, these aquatic resources remain at risk. Today's challenges include resolving significant and complex pollution problems. These pollution problems include minimizing the effect of non point pollution sources , maintaining safe drinking water supplies, and protecting and restoring the health and integrity of aquatic ecosystems. The highest ground, such as a mountain, hill or ridge, forms the boundary between two watersheds. At these boundaries, rain falling on one side flows toward the low point of one watershed, while rain falling on the other side of the boundary flows toward the low point of a different watershed.
Individual watersheds combine to form larger watersheds, which are sometimes called basins.
The quality of water in a watershed is affected by every source of pollution in that watershed. The watershed protection approach is an integrated, holistic strategy for more effectively restoring and protecting aquatic resources. Thus, for a given watershed, the approach encompasses not only the water resource, such as a stream, river, lake, estuary, or aquifer, but all the land from which water drains to the resource. To protect water resources, it is increasingly important to address the condition of land areas within the watershed because as water drains off the land or leaches to the ground water it carries with it the effects of human activities throughout the watershed. The watershed protection approach is characterized as being action oriented, driven by broad environmental objectives, and involving key stakeholders.