Horne: Normally you wouldn't look to a sewage treatment plant or a chemical treatment plant as a place where you want to live if you're a bird.

Narrator: : This is Science Today. Ecologist Alex Horne of the University of California, Berkeley creates artificial wetlands -- swamps, basically. He's discovered that they're an efficient way to clean pollution from streams, rivers and other sources of drinking water. Birds and animals like them, too. Artificial wetlands often serve as refuges for rare and endangered species. But Horne makes an important distinction:

Horne: I'm not in the business of reconstructing historical wetlands. That's a different scope and a different field.

Narrator: : He points out that in modern society, it's impossible to restore all natural wetlands the way they were. Artificial ones will have to do -- and he says they do pretty well.

Horne: And certainly for the next 50, 100 years that's going to have to be the way we go. We can't get rid of everybody and recreate the wetlands we used to have, but we can make some new wetlands that do a lot of work, and if I was a bird or a frog I'd say, okay, it's not perfect, but it'll do for now.

Narrator: : For Science Today, I'm Steve Tokar.