Pollution affects water quality in lakes and other freshwater resources around the globe. It can take many forms from industrial, agricultural, or municipal sources; a few common examples include pesticides, herbicides, sewage, and litter. Lakes often contain high pollution levels relative to the surrounding landscapes and environment. Rivers and streams drain pollutants from the landscape where they concentrate in lakes and other water bodies. Aquatic species such as fish can be extremely high in contaminants as some pollutants don't readily dissolve and dilute in water and are instead taken up into organisms. Some species of aquatic organisms are particularly sensitive to pollution; they are used as indicators of pollution and are called bioindicators. Because lakes drain a large surrounding landscape, they reflect the processes and actions that operate around them. When chemicals are spilled, they can drain into nearby streams and be transported downstream into lakes.