If you’ve ever stood at Table Rock on the Canadian side of Niagara Falls, watching the water thunder past and feeling the mist on your face, you might have been tempted to imagine what this natural wonder must have looked like hundreds of years ago, before the casinos, hotels and haunted houses moved in. The truth? Pretty different.

Since the late 19th century, the falls have been heavily engineered to generate energy behind a flowing façade designed to appeal to the estimated 13 million tourists who visit each year. Essentially, this natural wonder is now a tap: huge tunnels channel the waters of the Niagara River around the falls, which ebb and flow according to the tourism calendar. 

A recent book by environmental historian Daniel Macfarlane reveals the technological feats and cross-border politics that facilitated the transformation of one of the most important natural sites in North America.

Read an excerpt below from Fixing Niagara Falls: Environment, Energy, and Engineers at the World’s Most Famous Waterfall.

Before the Second World War, engineers had envisioned a series of submerged weirs as well as various configurations of control dams. But the models now indicated that these would not be flexible enough to meet the treaty’s flow parameters. A control structure with gates, what some might term a dam, which could maintain the pool level for power diversions while also distributing the flow to the cataracts in a satisfactory way, emerged as the backbone of a new water control regime, along with fills and excavations to reconfigure the riverbed and lip of the cataract. The 1949 Federal Power Commission report on Niagara development had placed this control structure near the outlet of Lake Erie at Buffalo, some eighteen miles upstream. But engineers now believed that the optimal location was right above the Falls. In addition to a control structure, the remedial works would include reclaiming the flanks of the Falls so that no unsightly trickles would be obvious and a greater volume of water could be channelled to the shortened crest of the Falls. These fringes would be reclaimed and landscaped to serve as viewing areas. 

This speaks to the hybridity inherent in the design. Organic elements were accommodated and factored into their mechanical creation, incorporated as part of the dynamic infrastructure: i.e., the new envirotechnical system engineers were creating would not work properly without normal weed growth and ice formation. Designing remedial works and power station intakes to withstand or deal with ice, particularly frazil ice, was a paramount concern. Formative studies of the impact of ice formation had been done in the Niagara River over the previous century, and many of the engineers from Ontario Hydro and the US Army Corps of Engineers were on the leading edge of ice studies. There was still “a dearth of factual data” about ice, however. 

Whereas a “controlling criterion” in the studies underpinning the 1929 Niagara Convention and Protocol was a satisfactory depth of water in the high-flow section of the Horseshoe Falls in order to create a satisfactory colour effect, now complete coverage of the flanks was equally important. But what was the acceptable minimum depth and distribution? Several aspects had changed, after all, since 1929: there was the submerged weir, and additional diversions had been authorized in the 1940s. The engineers “agreed that an attempt would be made to establish a scenically satisfactory flow per foot over the flanks in advance of the tests in order to present a target at which the tests would aim.”