Lakes and Ponds

Graphic artwork of frog and lily pads in lake with sun in background — Lakes and Ponds artwork by D. Caldwell for NPS.

Simply defined as still bodies of water surrounded by land, lakes and ponds are normally classified as lentic (still fresh water) ecosystems. These systems include biotic (living) plants, animals, and microorganisms, as well as abiotic (non-living) physical and chemical interactions. Ponds are typically smaller and have their entire bottom surfaces exposed to light, while lakes are larger and murkier.

Lakes are created when basins in the earth are filled with water, which can happen a few ways. Glacial lakes are formed from melted glaciers–this is how many North American lakes came to be, including the Great Lakes. They can also be created through faults from plate tectonics, erosion of rivers, or beaver dams. Surprisingly, even volcanoes can create lakes. When the top of a volcano collapses, it sometimes leaves an indentation called a caldera that may fill with rain.

These bodies of water require the right amounts of chemicals such as nitrogen and phosphorous to sustain their food webs. When the balance is off, harmful algal blooms can occur. Certain types of pollution–such as fertilizer runoff from agriculture–can saturate the lake with too much nitrogen and phosphorous, causing cyanobacteria to grow out of control and block other lake organisms from acquiring needed nutrients. In extreme cases, harmful algal blooms can cause hypoxia: the surplus bloom of algae dies, and its decomposition process consumes the oxygen that the lake’s plants and animals need.

There are National Natural Landmarks designated for their lakes and ponds nationwide that illustrate the beauty and diversity of these ecosystems. Some of these include:

Walker Lake, AK

Willcox Playa, AZ

Hanging Lake, CO

Paynes Prairie, FL

Okefenokee Swamp, GA

Kanahā Pond, HI

Horseshoe Lake Nature Preserve, IL

Anderson Goose Lake, IA

Penney Pond-Joe Pond Complex, ME

Cupola Pond, MO

Red Rock Lakes National Wildlife Refuge, MT

Pondicherry Wildlife Refuge, NH