Nature and man have stopped waterfalls from flowing

“Can you turn off waterfalls?” asked a young patron from the Arlington Heights Memorial Library.

Waterfalls top the list of nature's masterpieces. Waterfalls can be remarkable for height, volume or sheer dazzle, especially when the sun's rays weave prisms through the cascades.

Some are massive, like the roaring 2-mile-wide Iguazú Falls bordering Argentina and Brazil, where the Iguazu River spills over the precipice of the Paraná Plateau. Cascades create nearly 300 falls, including the showstopper — the 20-story torrent called Devil's Throat.

Even the small flows at Starved Rock and Matthiessen State Parks in Illinois attract thousands of hikers who trek across paths surrounding the falls.

Occasionally, nature creates havoc with its masterpieces.

Early last year, a powerful magnitude 7 earthquake struck a resort area in China's southwestern Sichuan province. The country's widest waterfall, Nuorilang, cracked and was completely drained by the devastating earthquake. Restoration is underway to repair breaks so this once mighty falls can stream across a craggy two-story drop.

An earthquake in Mexico had a similar effect. In 2017, Agua Azul waterfalls in southern Chiapas State was destroyed by an 8.2 magnitude earthquake. Workers have since restored the falls by redirecting rocks to facilitate water flow.

Niagara Falls, a massive trio of falls spraying from a 160-foot drop in the Niagara River, is on the border of the U.S. and Canada. The largest, Horseshoe, flows on the Canadian side. The American and Bridal Veil falls make up the U.S. side.

In 1965, concerns that the American Falls was eroding prompted leaders to “dewater” by constructing a dam at Goat Island, a landform that divides the falls. Engineers redirected the flow from dams for a period of six hours, slowing the Niagara roar to a trickle.

Tree trunks, rocks and a 10-ton pontoon boat wedged in the rapids were plucked from the river bed.

A monthslong dewatering was planned to take place a few years later to bolster underlying rock and shoreline. In 1969, a helicopter strung a lifeline from the shore to Goat Island so workers could safely construct a dam. With the dam in place, water was diverted, and engineers threaded pipes and rebuilt rock face that might have eroded without intervention.

Waterless falls became a major tourist attraction. Calls to improve walkways or minimize erosion could stop the falls again in the future.