What are lakes and ponds?

Lakes and ponds are inland bodies of surface water, usually fresh. They provide valuable habitat for a variety of organisms, including fish, amphibians, insects, and plants. They can also be important sources of drinking water for both humans and wild animals.

Generally speaking, ponds are small bodies of water shallow enough that light can penetrate to the bottom, while lakes are deeper basins with a dark region near the bottom that sunlight does not reach. But these distinctions are not very scientific, and ponds and lakes are much the same ecologically and hydrologically. No matter the size, the edges of these water features include unique environments where semiaquatic plants can flourish, providing nursery habitats for freshwater fish, juvenile amphibians, and various insects. 

Lake and pond waters also tend to be very sensitive to pollution and environmental changes. Unlike rivers and streams, where the flow of water provides at least some natural filtering effects, a buildup of pollutants in the slow-moving or still waters of a lake can persist for long periods of time. 

Some communities rely on lakes as reservoirs for drinking water and sanitation, meaning clean lakes are important not just for biodiversity, but for human health.

How do we study lakes and ponds? 

Mapping and monitoring global surface waters is one of the missions of NASA’s Surface Water and Ocean Topography (SWOT) mission. SWOT uses a radar interferometer to conduct high-resolution mapping of all of Earth’s watery surfaces. ICESat-2 also helps track inland surface waters using a laser altimeter.

These satellites can pick up subtle variations in the landscape, so identifying areas where the surface appears nearly perfectly flat lets scientists identify freshwater bodies, even in remote locations that could be difficult to reach and study. The missions provide continual monitoring of surface water bodies that help scientists track changes in the water levels of reservoirs and lakes.

NASA also monitors water quality in lakes and ponds. The Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission observes water color across a wide range of the electromagnetic spectrum, including major inland waters like the Great Lakes. PACE's observations can be used to identify and track harmful algal blooms that can harm local wildlife and reduce local water quality for drinking and recreation.

What can we do with lake and pond observations?

NASA provides datasets for monitoring water levels and water quality in lakes around the world. These data can help ecologists studying conditions that could affect local biodiversity or water resources for drinking and irrigation. 

In arid regions, monitoring lakes is also an important indicator of climate change. Hotter summers and drier winters are causing some lakes to shrink, and in areas far from the coast where these are primary sources of  water, this can present a major humanitarian challenge. Satellite observations make it possible to help predict and plan around freshwater changes.