Cristina Milesi, a remote-sensing scientist at California State University-Monterey Bay and at NASA/Ames Research Center in Moffett Field, Calif., after witnessing how much water is wasted on landscapes in the U.S., used census data, satellite images, and aerial photographs to estimate how much turf grass was in the 48 contiguous states. Then, she applied a computer simulation that revealed the environmental impact based on care of the grass.

Her results found that turfgrass is the single-largest irrigated crop in the United States, three-times more than corn.

“We really undervalue water as a resource,” Milesi says. What she found was surprising. While lush lawns take in lots of water, they also take in carbon dioxide. Experts, however, say this is not enough of a benefit to keep a beautiful green landscape. Conservation is now mandatory in some cities, and some are even paid to switch to native plants and grasses.

Other ways to save water is to program sprinklers for three to four minutes at sunrise and sunset, don’t water during the heat of day or in windy conditions, and soak the ground no more than four inches deep.