What’s the difference between a lake and a pond?

What’s the difference between a lake and a pond?

You’d think it’s a matter of size —  lakes are bigger, ponds are smaller. That’s actually wrong. The difference is in fact, a matter of depth, not surface area.

Ponds, according to limnology (the study of water bodies) are shallow enough that plants could conceivably grow across the entire water body. This entire area where plants could grow is known as the “photic zone,” the area where sunlight can reach the bottom and stimulate plant growth. It’s also called the “euphotic zone.”

A lake, by contrast, has an “aphotic zone,” meaning there is an area deep enough that “less than 1 percent of sunlight penetrates,” according to Wikipedia.

The photic zone is determined by water clarity, so it can vary from just a few feet deep to over 30-feet. I once visited a lake infested with zebra muscles, known for eating everything suspended in lake water, turning murky water crystal clear. The lake was so clear, you could see weeds growing on the bottom at 35-deep — zebra muscles had turned that lake into a pond!

Some small bodies of water are deep enough to be lakes  — and some very large water bodies that are technically ponds.

For example, Florida’s Lake Okeechobee is huge, with a surface area of 730 square miles, but it’s deepest part is just 12 feet — and its average depth is just 9 feet. By definition, Okeechobee is actually a pond. But if you go there, call it a lake, or “Lake O’” as the locals say.

In contrast, Sugarbush Lake near my home in Michigan is just over 1/2-square mile, yet it’s 93-feet deep and was used to instruct deep-water diving.

If you’d like to know about all the zones in your lake or pond, this Michigan State University article (link) clears it up nicely.

So, at least with lakes and ponds, size doesn’t really matter.

— Douglas Fast