See the context of this sign.

The Cottonwood Spring Oasis

The spring is ancient, but two centuries ago only a scattering of
mesquite, squaw baccharis, and a few other moisture loving plants
grew around its edges. These palms and cottonwoods were planted
by freight haulers and prospectors who thirstily sought out the
spring as one of two water sources between the Dale Mining
District and Mecca between 1890 and 1910.

Early in this century, as much as 3,000 gallons of water were
pumped from Cottonwood Spring every day - enough to pipe 18
miles to the Iron Chief Mine in the Eagle Mountains. In recent
years, the water supply dwindled to only a few gallons a day, until a
shift in the water table brought about by the 1971 San Fernando
earthquake increased water production to its present level of 30
gallons an hour.

Look and listen for birdlife! Cottonwood Spring attracts most of the
monument's 200 or so species.

With its palms, greenery, and birdlife, Cottonwood Spring oasis
looks as nature as the monument's other three oases - it its
appearance today is largely the work of man.

Don't miss the rest of our virtual tour of Joshua Tree National Park in 1588 images.