Lake vs. Reservoir

What's the Difference?

Lakes and reservoirs are both bodies of water, but they differ in their origins and purposes. Lakes are natural formations, typically formed by geological processes such as tectonic activity or glacial erosion. They are often found in valleys or depressions and are sustained by rainfall, rivers, or underground springs. Reservoirs, on the other hand, are man-made structures created by damming rivers or streams. They are designed to store water for various purposes, such as irrigation, drinking water supply, or hydroelectric power generation. While lakes are generally more ecologically diverse and support a wider range of plant and animal life, reservoirs serve as important water management tools and can provide essential resources for human activities.


Photo by Alice Triquet on Unsplash
DefinitionA large body of water surrounded by land.A man-made or natural water storage area created by damming a river or stream.
FormationNaturally formed through geological processes.Artificially created by humans.
OriginCan be formed by tectonic activity, glacial activity, volcanic activity, or due to erosion.Created by humans for various purposes such as water supply, irrigation, flood control, or hydroelectric power generation.
SizeCan vary greatly in size, ranging from small ponds to large bodies of water like the Great Lakes.Can also vary in size, but often larger than natural lakes due to human intervention.
Water SourcePrimarily fed by rivers, streams, and precipitation.Usually filled by diverting water from rivers or streams.
Water LevelWater level can fluctuate naturally due to rainfall, evaporation, and groundwater inflow.Water level can be controlled by humans through dam operations.
EcosystemSupports diverse aquatic life and ecosystems.Ecosystems can be altered or disrupted due to human activities and water management.
UsageUsed for recreational activities, drinking water supply, and habitat for various species.Used for water supply, irrigation, hydroelectric power generation, and sometimes recreational activities.
RegulationRegulated by natural processes and environmental factors.Regulated by human management and dam operations.
Photo by Marcus Woodbridge on Unsplash

Further Detail


Lakes and reservoirs are both bodies of water that play significant roles in our environment and society. While they share similarities, they also have distinct attributes that set them apart. In this article, we will explore the characteristics of lakes and reservoirs, their formation, ecological importance, human uses, and the challenges they face.


Lakes are typically formed through natural processes such as tectonic activity, glacial activity, volcanic activity, or the filling of a basin by precipitation or groundwater. They can be found in various landscapes, including mountains, valleys, and plains. Reservoirs, on the other hand, are artificial bodies of water created by humans for specific purposes, such as water supply, irrigation, flood control, or hydroelectric power generation. Reservoirs are usually formed by constructing dams across rivers or streams, which impound water and create a reservoir behind the dam.

Size and Depth

Lakes come in a wide range of sizes, from small ponds to massive bodies of water like the Great Lakes in North America. They can vary greatly in depth as well, with some lakes being shallow and others reaching great depths. Reservoirs, on the other hand, tend to be smaller in size compared to lakes. They are often designed to have a specific capacity to meet the intended purpose, and their depth can be controlled by adjusting the dam's gates or valves.

Water Source

Lakes primarily rely on natural sources of water, such as rivers, streams, precipitation, and groundwater. They are often part of a larger hydrological system, receiving inflow from upstream sources and releasing water downstream. Reservoirs, on the other hand, are typically fed by rivers or streams that are impounded by dams. The water stored in reservoirs can be regulated and controlled to meet various needs, including water supply during dry periods or flood prevention during heavy rainfall.

Ecological Importance

Lakes and reservoirs provide vital habitats for a wide range of plant and animal species. They support diverse ecosystems and contribute to biodiversity conservation. Lakes often have a more natural and stable ecological balance, as they have evolved over long periods of time. They can support unique species and provide important breeding grounds for migratory birds. Reservoirs, although artificial, can also support various aquatic species and provide opportunities for recreational fishing and boating.

Human Uses

Lakes and reservoirs serve numerous purposes for human societies. Lakes are often used for recreational activities such as swimming, boating, and fishing. They can also be a source of drinking water for nearby communities. Additionally, lakes can be utilized for hydroelectric power generation, as the flow of water can be harnessed to produce electricity. Reservoirs, being man-made, have more specific human uses. They are crucial for water supply in many regions, providing water for drinking, irrigation, and industrial purposes. Reservoirs also play a significant role in flood control, reducing the risk of downstream flooding during heavy rainfall.

Challenges and Conservation

Lakes and reservoirs face various challenges that impact their health and sustainability. Pollution from human activities, such as industrial discharge, agricultural runoff, and improper waste disposal, can degrade water quality and harm aquatic life. Eutrophication, caused by excessive nutrient inputs, can lead to harmful algal blooms and oxygen depletion. Invasive species can also disrupt the natural balance of ecosystems in both lakes and reservoirs. Climate change poses additional threats, including altered precipitation patterns, increased evaporation, and rising water temperatures.

To ensure the conservation and sustainable management of lakes and reservoirs, efforts must be made to reduce pollution, promote responsible water use, and protect natural habitats. Monitoring water quality, implementing effective watershed management practices, and raising awareness about the importance of these water bodies are crucial steps towards their preservation.


Lakes and reservoirs are valuable resources that provide numerous benefits to both the environment and human societies. While lakes are natural formations that have evolved over time, reservoirs are artificial bodies of water created for specific purposes. Both have unique attributes, including their formation, size, depth, water source, ecological importance, and human uses. Understanding and appreciating these differences can help us better manage and conserve these vital water resources for future generations.

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