But after a powerful earthquake hit the country, they dried up -- and the area's once-booming tourist economy along with them.

The state of Chiapas, where the falls trickle near the ancient Mayan ruins of Palenque, was the epicenter of the 8.2-magnitude earthquake that struck Mexico on September 7, killing 96 people.

Besides flattening houses and buildings across a broad swathe of southern Mexico, the quake, along with thousands of aftershocks, also altered the bed of the Agua Azul river.

The tremors -- together with the normal erosion of the limestone whose minerals give the water its bright color -- collapsed a portion of the river's left bank, said Mexico's National Water Commission.

That shifted the flow of water to another branch of the river and caused the water level to drop by nearly a meter (three feet), leaving the falls completely dry in many places.

Locals watched in alarm this month as the water dried up from one day to the next, making them fear for the future of a tourist attraction that draws thousands of visitors a day from around the world.

"If there are no tourists, there are no jobs," local businessman Juan Manuel Hernandez told AFP.

The government vowed to study the problem and seek a solution.

But not content to sit back and wait, locals have taken matters into their own hands.

Using shovels and pickaxes, they partially restored the riverbed to its original course, bringing back a trickle of the famously bright blue water.

After moving as much stone and sediment as they could by hand, they have asked the authorities for heavy machinery they hope will help them bring the falls back to their full flow.

Mexicans have a tradition of springing into action after earthquakes, stepping up when overwhelmed authorities don't.

After the September 7 quake and another on September 19 that leveled dozens of buildings in Mexico City, killing 369 people, volunteers flooded the streets to pull survivors from the rubble, bring emergency supplies and even provide free legal services and psychological counseling.