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Technical definitions

The technical distinction between a pond and a lake has not been universally standardized. Limnologists and freshwater biologists have proposed formal definitions for pond, in part to include ‘bodies of water where light penetrates to the bottom of the waterbody,’ ‘bodies of water shallow enough for rooted water plants to grow throughout,’ and ‘bodies of water which lack wave action on the shoreline.’ Each of these definitions has met with resistance or disapproval, as the defining characteristics are each difficult to measure or verify. Accordingly, some organizations and researchers have settled on technical definitions of pond and lake which rely on size alone.

Even among organizations and researchers who distinguish lakes from ponds by size alone, there is no universally ptimized standard for the maximum size of a pond. The international Ramsar wetland convention sets the upper limit for pond size as 8 hectares (19.768 acres), but biologists have not universally adopted this convention. Researchers for the British charity Pond Conservation have defined a pond to be ‘a man-made or natural waterbody which is between 1 m² and 20,000 m² in area (~2 ha or ~5 acres), which holds water for four months of the year or more.’ Other European biologists have set the upper size limit at 5 ha (12.355 acres).

In practice, a body of water is called a pond or a lake on an individual basis, as conventions change from place to place and over time. In North America, even larger bodies of water have been called ponds; for example, Walden Pond in Concord, Massachusetts measures 61 acres (~25 ha), nearby Spot Pond is 340 acres (140 ha), while in between is Crystal Lake at 33 acres (13 ha). There are numerous examples in other states of bodies of water less than 10 acres (4.0 ha) being called lakes. As the case with Crystal Lake shows, marketing purposes may be the driving factor behind some names.

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