(
Moses-Saunders Power Dam Satellite,
Long Sault Dam Satellite)
Long Sault Dam is effectively the emergency spillway for the Moses-Saunders Power Dam. Normally, the entire flow of the St. Lawrence River would go through the power dam to maximize the production of electricity. For simplicity, I'm going to refer to these two dams as the Cornwall Dam. I've seen the "Cornwall Dam" reference in news articles. The slack pool created by these dams is called Lake St. Lawrence.
 |
| Facebook, lots of gates are open because gates are closed at the power dam for routine turbine maintenance. Seeing this significant flow gives us great insight as to how big the flow is through the power dam. The river flow is more than the flow going over Niagara Falls because some of the flow of the Niagara River is diverted through powerhouses. Furthermore, the watershed for these dams is greater than the watershed for the Niagara Falls. |
When they built a 9' navigation channel in an American river such as the Upper Mississippi, Ohio, Illinois, Tennessee, etc., they didn't dig down 9', they built a lock & dam to raise the level of the water to create a series of slack pools. To create the 26'+ navigation channel in the St. Lawrence river, these "slack pools" are big enough to be called lakes. Lake St. Lawrence is created by the Cornwall Dam and creates a pool 26'+ deep at the foot of the
Iroquois Lock and Dam.
Unlike a 9' rise in water level, a 26' rise is significant enough that it flooded some of the towns that were on the original shores of the St. Lawrence River. I have already described how
the entire town of Iroquois was moved up a hill.
As a result of the tanker
Chem Norma becoming stuck on an embankment, I learned that Morrisburg, ON was another town that was partially flooded when they closed the gates of the Cornwall Dam. The ship strayed off course because it had an issue with its rudder. As with all tankers on the St. Lawrence Seaway, it is double hauled. There were no pollution issues. [
GreatLakes-Seaway] (After they freed it and inspected it, not even the outer haul was damaged.) I've already
described how they first tried to use a lot of horsepower (three tugboats and the ship) to free it. They ended up raising the level of Lake St. Lawrence a little and then all of that horsepower was able to pull the ship free.
This image is part of an analysis of what the tanker got stuck on. It shows us that the part of Morrisburg that got flooded included some old locks. Specifically it was Lock 23 built in the 1800s.
Not only did Lake St. Lawrence require that 6,500 people be moved to higher ground, the native Mohawk people of Akwesasne, who lived in this traditional territory for centuries, lost much of their land including islands, fishing sites, and both burial and sacred sites. [
OntarioPowerGeneration]
The power dam is more than a half-mile long and contains 32 turbines. Note how the border goes right through the middle. The 16 turbines on the Canadian side are operated as the
Robert H. Saunders Generating Station. The 16 turbines on the American side is the
Robert Moses Power Dam, and it can produce 800,000 kilowatts of electricity for the New York Power Authority. The cheap electricity supports the regional economy by supporting aluminum, zinc, and glass companies.
The International Lake Ontario - St. Lawrence River Board (River Board) is responsible for controlling the flows through the
Iroquois Dam and these dams. The power dam should have been designed so that the ideal river flow is the capacity of the powerhouse with no water going over the spillway dam. The effect of these dams on the river is significant enough that upstream is considered the "upper St. Lawrence River" and downstream is considered the "lower St. Lawrence River." The "upper St. Lawrence River" is basically Lake St. Lawrence. To determine the outflow of the dams, the River Board considers the need of the powerhouse, maintaining a minimum depth in the navigation channel, and water levels for Lake Ontario and the upper and lower St. Lawrence River. If water levels are too high, it increases erosion of the shoreline and it can flood property. If it is too low, then the water intakes for towns along the river provide an inadequate flow to the town. And people's boats can't reach their piers. When determining the outflow rate, the River Board must also consider precipitation in the watershed and evaporation from Lake Ontario. Water flow through the locks is negligible. If outflows are high, then commercial shipping is stopped because the river currents are too dangerous.
Three plans as to how to determine the river flow had been written: 1952, 1956, and 1958D. In 2014, work began a new plan "to improve ecosystem health and diversity on Lake Ontario and the upper St. Lawrence River....Allowing for more natural variations of water levels, the plan aims to foster the conditions needed to restore Lake Ontario and upper St. Lawrence River coastal wetlands and improve habitat for fish and wildlife. The plan will also frequently extend the Lake Ontario recreational boating season in the fall, better maintain system-wide levels for navigation and allow for a modest increase in hydropower production compared to the previous plan." Plan 2014 became effective Dec. 8, 2016. [
ijc]
An additional issue the River Board must consider is the formation of a stable ice cover. When ice starts to form, the outflows are reduced to allow an ice cover to form. After a stable ice cover forms, the flows can be increased. Furthermore, if the Ottawa River is causing flooding in the Montreal area, outflows are reduced to reduce the extent of the flooding in the Montreal area. [ijc]
But in 2017, Mother Nature dumped a record amount of precipitation into Ontario Lake
causing flooding.
Unfortunately, Mother Nature also dumped a lot of precipitation in the Ottawa River watershed and
flooded Montreal. People living on the shores of Ontario Lake were calling for higher outflows.
Letting out enough water to lower Lake Ontario by 1 inch would raise the level of the river at Montreal by nearly a foot, says the International Joint Commission, which controls water levels. Letting less water out of the lake until the Ottawa River peaks "can prevent several feet of flooding in the Montreal area," said commission spokesman Frank Bevacqua. During nine days in April and May when the Ottawa River was high, the commission let less water out of Lake Ontario, Bevacqua said. The commission plans to start discharging more water from the lake as the water levels near Montreal begin to recede, Bevacqua said. [NewYorkUpstate-flooding]
Below the above article is this drought information. But I think the flooding was May 10, 2017 and this drought article is current (Sep 7, 2018). I still get the printed Chicago Tribune delivered to my house, so I'm not experienced with reading "web news." But the juxtaposition of old and new articles does demonstrate that Mother Nature can have significant "mood swings."
 |
| A severe drought (orange) is now affecting parts of the Adirondacks, while 20 percent of New York remains in a moderate drought (tan) or is considered abnormally dry (yellow). (U.S. Drought Monitor) |
New York's Gov. Andrew Cuomo demonstrated that he is another politician that makes statements before consulting with his experts because he joined the Ontario Lake residents asking for more water to be released downstream. [
NorthCountryPublicRadio]
Evidently the water level in the lower St. Lawrence River is now low enough that they have been able to use the spillway and powerhouse to increase the outflow. But this creates another problem, low river levels on the downstream end of Lake St. Lawrence. An organizer of a Sep 11, 2018 meeting to complain about the low levels claims parts of the river are now down to the bare minimum needed to support commercial shipping --- something not seen since at least 1998.
I found the NationValleyNews link in a Facebook
posting.
Why don't they open the gates at the Iroquois Dam as well to match the flow being spilled by the Cornwall Dam to maintain the traditional height of Lake St. Lawrence? Especially since they want to get water out of Lake Ontario?
I think I now understand. I'm looking at a photo at the downstream part of Lake St. Lawrence. As the flow increases, the "lake" turns back into a river and the water slopes downstream from Iroquois to Cornwall causing the water level to be significantly lower at the Cornwall end. Basically, the water management people have done such a good job for so many decades that people think they bought land on a lake instead of a river. At least they have the advantage that the exception is that the water goes down instead of up. Most people that live on a river get flooded, not drained, by abnormal weather. For example the Mid-Continental Railway Museum got hit this summer by the Baraboo River. They were still trying to recover from a 2008 flood. https://www.facebook.com/.../a.22924.../2293066620709671/...
Even a true lake can be at the mercy of Mother Nature's precipitation moods. Lake Michigan varies by about six feet. When Lake Michigan went down after Chicago reversed the flow of their river, Wisconsin sued the sanitary district to reduce the flow. Water Treatment Plants were invented and a lock was installed at the mouth of the river to reduce the flow out of the lake. Later, when the lake went back up, Chicago was asked to open the locks and allow big flows again. Chicago refused because the outflow was a drop in the bucket compared to what Mother Nature was adding and because a heavy river flow would disrupt barge traffic.
Update Oct 2, 2018: the flow will be reduced so the water level near the Cornwall Dam should go up about 2 feet.
The international board said this week that it will temporarily decrease outflows significantly over two 45-hour periods during the first two weekends of October to provide an opportunity for residents of Lake St. Lawrence and upstream of that area to remove their boats and other equipment while the river level rises.
“These flow decreases will temporarily raise Lake St. Lawrence levels, which will assist marinas, yacht clubs and other recreational boaters in the area in removal of their boats prior to winter,” according to the organization’s statement. “The board acknowledges the concerns identified at recent meetings with the public in the area, and the board takes each concern very seriously. The exact amounts of the water level rises will vary depending on a number of factors, including location, winds and other secondary factors.”
[WaterTownDailyTimes]
I notice there is are bins, piles of materials, a crane and conveyor belts in the background of the above photo. But there is none of this infrastructure in a satellite image.
After studying a satellite image, I noticed that the levels at Ogdensburg are controlled by the
Iroquois Dam instead of the Cornwall Dam. The article says the flow reduction will raise the water level at Ogdensburg just three inches instead of the two feet expected near the Cornwall Dam.
South Stormont is another town near the Cornwall Dams that is complaining about the low water levels. It is not just a matter of the people along the shore refusing to convert to floating docks, the exceptionally low water levels is exposing hazards to navigation. They claim it is impacting commercial as well as recreational boats.
“What if an oil ship gets punctured? It could be a disaster and that’s the point I’ve tried to get across to the IJC.” But I can't believe the River Board would jeopardize the 26'+ draft of the Seaway navigation channel. [
CornwallSeawayNews] Of note, all tankers on the Seaway are required to be double hulled.
