Reservoir

Combining how the European Environmental Agency and US EPA define them, “reservoirs are human-made lakes created by the damming of rivers or streams to serve one or more purposes, such as hydropower production, water supply for drinking, irrigation and flood protection.” This means that reservoirs are associated with dams that “control the amount of water that flows out of the reservoir” which has applications in “controlling flooding” as well [2]. These dams are important for making the distinction between lakes and reservoirs, as “in fact, a reservoir is a man made lake that is created when a dam is built on a river. River water backs up behind the dam creating a reservoir” [4]. Another defining visual characteristic of reservoirs is “very still” water, leaving “bits of sand, rock, dirt, and other material, called sediment, to sink to the bottom, leaving the water quite clear,” though “this sediment builds up” over time [2].

Though reservoir construction can yield immense economic benefits, “construction may lead to a number of environmental issues,” including “reservoir rise upon the closing of the dam." This results in “major changes in the area inundated with the water” such as lost “farmland settlements flooded, and the groundwater table elevated,” and “once the reservoir has been established, environmental problems” like “algae and toxic substances in reservoirs used for drinking water and ecological deterioration of the river system." The EEA also remarks that these changes may impact “access to spawning sites for migratory fish, preventing access, which is a particular problem for fish such as salmon, trout, eel and sturgeon" [1].

Reservoirs can also be recognized by their apparent scale, which helps set them apart from “natural lakes,” which “are distributed fairly evenly in size from small to large while most man made reservoirs are relatively small. For example, 40% of reservoirs are less than 10 acres (4 hectares) compared to 22% of lakes” [3].

References

[1] European Environmental Agency (EEA). (2018, November 7). Reservoirs and dams. Retrieved (2021, July 9), from https://www.eea.europa.eu/archived/archived-content-water-topic/reservoirs-and-dams

[2] Rutledge, K., Ramroop, K., Boudreau, D., McDaniel, M., Teng, S., Sprout, E., Costa, H., Hall, H., & Hunt, J. (2013, March 28). Reservoir. National Geographic Society. Retrieved (2021, July 9), from https://www.nationalgeographic.org/encyclopedia/reservoir/

[3] United States Environmental Protection Agency (US EPA). (2018, June 7). National Highlight - Comparing Natural Lakes and Manmade Reservoirs. Retrieved (2021, July 10), from https://www.epa.gov/national-aquatic-resource-surveys/national-highlight-comparing-natural-lakes-and-manmade-reservoirs

[4] United States Geological Survey (USGS) – U.S. Department of the Interior. (n.d.). Lakes and Reservoirs. Retrieved (2021, July 10), from https://www.usgs.gov/special-topic/water-science-school/science/lakes-and-reservoirs?qt-science_center_objects=0#qt-science_center_objects