The Hidden Engineering of Niagara Falls

[00:01] Niagara Falls is one of the most spectacular  waterfalls in the world. With a vertical   drop of more than 50 meters or 164 feet  and a flow rate that often exceeds 2800  

[00:13] cubic meters per second or 100,000 cubic feet per  second, it’s one of North America’s crown jewels.   Roughly ten million people visit the falls every  year just to catch a glimpse of the curtains of  

[00:26] water pouring over the edge and the constant  clouds of mist at the bottom. But Niagara Falls   isn’t just a tourist attraction. The special  geology and hydrology of this region, situated  

[00:39] between Lake Erie and Lake Ontario, have resulted  in some fascinating feats of infrastructure,   from shipping to electricity to water control.  It’s basically a microcosm of all the things  

[00:51] I love. The falls themselves have required  quite a bit of engineering over the years,   and they’ve even been shut off for maintenance.  Let’s take a little tour of the Niagara Peninsula   aren’t usually listed in a guidebook. I’m  Grady, and this is Practical Engineering.

[01:21] This is a map of the isthmus. We’ve got Lake Erie to the south,   Lake Ontario to the north, Buffalo and western  New York to the East, and Ontario, Canada,  

[01:33] to the west. The Niagara River runs northward,  connecting the two great lakes. And right in the   middle, it plunges off the Niagara Escarpment,  creating the famous falls. On the US side,  

[01:45] there are the American Falls and the smaller  Bridal Veil Falls. And on the Canadian side is   the Horseshoe Falls where a majority of the river  flows. It’s pretty impressive to see in person,   but it’s actually not entirely a benefit. Because  these falls pose a major problem for shipping.

[02:02] The Great Lakes form the largest inland freshwater  transportation system in the world. Since the 19th   century, they’ve served as the backbone for  moving iron ore, coal, grain, and manufactured  

[02:14] goods between the American heartland and the  Atlantic Ocean. Ore from Minnesota and grain   from the Midwest can travel by ship all the way to  steel mills or export terminals on the East Coast.  

[02:26] Barges and freighters are efficient at moving  bulk cargo in a way rail and trucks can’t match.   For a time, the Niagara Escarpment was a natural  bottleneck between Lake Erie and Lake Ontario,  

[02:38] preventing goods from moving directly between  the upper lakes and the Atlantic. Freight had   to be offloaded and portaged around the falls  before it could continue its journey. The Erie   Canal solved the problem somewhat, starting in  1825, bypassing Lake Ontario. But it could only  

[02:55] accommodate smaller vessels, and even before the  Canal opened, another solution was being planned. The Welland Canal runs through the  peninsula west of the Niagara River,   connecting two massive areas by shipping traffic  for the first time in 1829. The canal fueled the  

[03:12] early growth of cities along the Great Lakes  and St. Lawrence River - including Cleveland,   Detroit, Milwaukee, Chicago, Toronto, Montreal,  and Quebec City - and it’s been rebuilt and moved   several times over its life. The Welland Canal  is really a titanic engineering achievement and,  

[03:29] were it not positioned next to one of the natural  wonders of the world, it would probably be famous   in its own right. Because of the huge difference  in elevation between the two lakes created by the   escarpment, eight separate locks are required  to allow ships to traverse between them. And  

[03:44] all different kinds do - from personal leisure  craft to the lakers that stay in fresh water   to the salties that travel between the lakes  and the ocean through the St. Lawrence Seaway. Starting on the upstream, Lake Erie side of the  canal, the first lock isn’t really for lifting  

[04:00] or lowering ships so much as for control. The  level of Lake Erie actually fluctuates throughout   the year, and there are longer-term trends as  well. Wind storms also raise the level locally   similar to the way storm surge works during  hurricanes. The control lock does just that:  

[04:16] it controls the level in the downstream  canal. It prevents excess water from   rushing down the canal when the lake  is high, kind of like an airlock on a   spaceship keeps air from rushing out when  astronauts step outside for a spacewalk.

[04:30] Downstream of the control lock, the canal  splits in two. The original pathway of the   canal flows through the eponymous town of Welland,  while the larger and newer section of canal,   the Welland Bypass… well, it bypasses  Welland to the east. If you look carefully,  

[04:45] you’ll also notice a small river, the  Welland River, which passes underneath   both the original and bypass canals. On the  way downstream from Lake Erie to Lake Ontario,   shipping traffic passes over aqueducts that pass  over a natural river. A hydrological wonderland!

[05:02] Continuing downstream from the aqueducts,  the remaining seven locks are lift locks,   more like what you think of when you imagine  a lock. Notice how they’re clustered tightly   around the terrain and not distributed evenly  along the length of the canal. That’s the Niagara  

[05:16] escarpment, the same geological feature  that the water cascades down at the falls.   This is the elevation diagram of the entire Great  Lakes and St. Lawrence Seaway system from Lake   Superior to the Atlantic Ocean, and you can see  that this drop is the biggest one of the whole  

[05:33] thing. And that’s pretty important for another  part of the infrastructure on the peninsula. The power available from a moving fluid  is directly proportional to the flow rate   multiplied by the height of the drop. In most  hydropower applications, that height is created  

[05:49] artificially by a dam. There aren’t that many  places in the world where you have both a   large volume of flowing water and a significant  natural drop in elevation. But that combination   made Niagara Falls the birthplace of large-scale  electric power in North America.

[06:07] opened the Edward Dean Adams  Power Plant, built with Westinghouse AC generators   based on the ideas and patents of Nikola Tesla.  The plant served as the basis for the modern  

[06:20] electrical grids we have today, and many of the  fundamental concepts are basically unchanged. But the power infrastructure at Niagara  Falls definitely has changed. Where the   Adams Power Plant put out about 40 megawatts  of power in 1895, now the combined capacity  

[06:37] from the region is in the neighborhood  of 5 gigawatts. But in both cases,   it wasn’t as simple as putting a turbine  at the base of the falls. While it might   be technically possible to generate power by  placing a water wheel directly in the stream  

[06:50] of a waterfall like a kid’s bath toy, it’s  not the most efficient way (plus it would   take away from the beauty). The water used to  power the hydroelectric plants on both the US   and Canadian sides of the Niagara River is water  that never actually flows over the falls. Instead,  

[07:06] it’s diverted into five massive tunnels - two  on the US side and three on the Canadian side. Like most tunnels, you can’t really  see the extent of the hydro tunnels   at Niagara Falls. There are a few conspicuous  clues though, like these gigantic buildings.  

[07:22] These interesting protrusions from the landscape  house enormous steel doors, nearly 60 feet tall,   that can drop down into the tunnels and close  off the flow for inspections and maintenance.  

[07:34] Both the Ontario and New York sides of  the river feature similar structures. From the tunnels, water flows into major  hydropower plants on both sides of the border:   the twin Adam Beck stations on the Canadian  side and Robert Moses station on the US side.  

[07:49] Then it’s released into the the lower part of  the river below the falls. When you add them up,   that’s 39 turbines with a combined  capacity of more than 4000 megawatts.   It’s a tremendous amount of power generation in  one place. But actually, that’s not all of it.

[08:06] These tunnels divert 50-75% of the flow of the  Niagara River. That wide range in percentage of   diversion isn’t because we don’t know how much  is diverted, but because we actually control  

[08:18] how much water is diverted, depending on the  tourist requirements agreed upon in a treaty   by both nations. During the day in peak tourist  season, more water is allowed to flow over the   falls to ensure the grandeur of the falls is on  full display for the huge crowds of tourists that  

[08:34] visit every year. At night and during the winter,  more of the flow is diverted to generate power.   That’s all managed by this structure upstream  of the falls: the international control dam.

[08:46] across the river. But it doesn’t need to. This  structure’s not meant to create a reservoir;   it just subtly adjusts the level in the river  to control how much water flows over the falls  

[09:00] versus into the hydropower intakes. The US  side of the Niagara River is pretty shallow,   so that side acts kind of like an uncontrolled  spillway. Then, the gates on the Canadian side   can be adjusted to balance the competing  demands on water between tourism and power.

[09:16] But there’s one big problem with those competing  needs: they both have the same timing. We want   thunderous cascades of water over the falls  during the day when tourists are visiting,   but daytime is also when the demand for  electricity is highest. It’s like if solar  

[09:31] panels only worked at night. To accommodate  this, both the US and Canada have pumped   storage plants. At night, excess electricity  is used to pump diverted water into reservoirs,  

[09:44] essentially storing both the power and the  extra water that’s available during off-peak   hours. Then, during the day, the water is released  back into the forebay of the power plants. You get   a little extra power from that drop out of the  reservoir into the forebays, so both sides have  

[10:00] small hydropower facilities to capture that.  But more importantly, you get a lot more water   during the day than would otherwise be available  to run through the big plants, making more power   when it’s needed most. And there’s just something  funny to me that the infrastructure is duplicated  

[10:17] on both sides of the river, like neither country  was willing to be one-upped by the other. All of this diversion noticeably  reduces the flow of water over the   falls. Even when they are at ‘full blast’  during the day in the tourist season,  

[10:30] only 50% of the flow of the Niagara River makes  it over the falls. You can imagine how powerful   the falls would be if 100% of the flow were to  cascade over. It might seem like this diversion  

[10:42] detracts from the majesty of the falls, but  in another sense, it actually preserves it. All waterfalls undergo some degree  of erosion as the water and sediment   suspended in it scours away the rocks and  soil underneath. Without any diversion,  

[10:56] Niagara Falls would be receding towards Lake  Erie at a rate of about 3 feet every year. At   the end of the last ice age, the falls were  right at the edge of the Niagara Escarpment,   but thousands of years of erosion have caused them  to work their way upstream. You can actually see  

[11:12] how far it’s already progressed by looking at this  elevation map. Over the last 12,000 years or so,   the falls have migrated by erosion to  their current location. By diverting a   significant portion of the flow, the power  plants have actually slowed the rate of  

[11:28] erosion to approximately one foot per year, which  will help preserve the falls for a longer period. While flow on the falls is downregulated by  diversion for hydropower, the falls are never   ‘turned off’...except for the one time in the  1960s. The smaller American Falls (and nearby  

[11:44] Bridal Veil Falls) have a pile of loose rocks  and boulders, called talus, at their base.   This pile of rocky debris actually extends  a good fraction of the way up the falls, and   officials worried that the falls might ultimately  transition into a series of rapids cascading down  

[12:00] the slope of talus rather than remaining a  majestic waterfall. So, in 1969, the Army   Corps of Engineers built a temporary cofferdam  between the New York shoreline and Goat Island,  

[12:12] diverting the water over the Canadian Horseshoe  Falls and leaving the American Falls dry(ish)! After the engineers got a chance to inspect the  situation, they determined that the best course   of action was just to leave the majority of the  talus in place, since it seemed to be stabilizing  

[12:29] the cliff face. Sometimes, doing mostly  nothing is a decision you make as an engineer,   even if you have to do a monumental amount  of work to come to that conclusion. So the   cofferdam was taken out, and water has flowed  continuously over all the falls since then.

[12:45] It really highlights the complexity  of Niagara Falls. On the one hand,   you have one of the natural wonders of the world,  an absolutely enormous set of waterfalls that   inspire awe and wonder in the countless travelers  who are lucky enough to take in the view. The  

[13:01] same thing that makes it impressive for tourists  (the big drop) makes it valuable for power and a   major challenge for shipping. And out of that  comes all kinds of fascinating infrastructure,  

[13:13] not only to facilitate the tourism but the other  stuff too: a major canal with locks and aqueducts,   the international dam control gates, pumped  storage reservoirs, epic tunnels, towering gates,  

[13:26] massive hydropower plants, and so much more. It’s  really a pretty remarkable place for engineering. My wife and  I actually visited the falls back in 2018, and  even crossed the Rainbow Bridge to the Canadian  

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