This is Scientific American Science Quickly. I'm Christopher Andaljata. When I first started working on this series about

Vernal pools and became convinced I had to go see some for myself, one of the things that surprised me the most was where people kept telling me to go to see them.

This landmark is by far the largest and most pristine concentration of Vernal pools left in San Diego County and possibly in California.

We're standing in a preserve of hundreds of acres of wild land containing more than a thousand Vernal pools.

It's also part of a marine base outside San Diego, Marine Corps air station Miramar.

And my tour guide was a wildlife biologist employed by the Department of Defense, a guy named Chuck Black.

Yeah, I never thought that I would be coming to a military base to find the the natural resource.

Yeah, yeah. Well, lots of people don't associate military bases with conservation efforts, but...

And it's true. When I think conservation, I think roadless stretches of the Sierra Nevada or remote patches of desert in the Mojave.

But here the natural wonder is sandwiched between a highway, a landfill, and a runway.

And there's a reason the military base is the largest remaining stronghold of Vernal pools along the southern California coast.

Lots of other stuff around here just got developed.

The flat mace of tops like this were the prime areas for development during the 1819th and 20th century.

The Vernal pools became farmland, houses, shopping centers.

It's estimated that over 98, 99 percent of the Vernal pools that formerly existed in San Diego are not here any longer because of the development.

And if you look statewide, the numbers really aren't that different.

And Vernal pools are considered one of the most threatened ecosystems in the state.

A lot of people know that 90 percent of Vernal pools have been lost from the Central Valley since European colonization.

But what people don't know a lot about is that these losses are ongoing.

This isn't just a historic problem.

This is Sean O'Brien. He's a senior wildlife biologist with ICF, that's a consulting firm.

And he does biological surveys of Vernal pools before developments.

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