Following 15 years of generally dry weather, the Great Lakes basin has experienced wetter conditions during the past four years. The four upper lakes – Superior, Huron, Michigan and Erie – are all well above average. Lakes Huron, Michigan and Erie are at their highest levels for this time of year since 1998. Lake Ontario and the St. Lawrence River were inundated with record-setting floods last year, but are now at lower levels than they were a year ago.
Water levels on the Great Lakes rise and fall in response to natural water supplies and levels change from day to day. Natural water supplies are the total inputs from rain, snow, runoff and inflows from upstream, minus evaporation from the lake surface. Outflows from lakes Superior and Ontario are regulated at dams approved by the International Joint Commission, allowing a limited degree of influence over high and low water levels. Lakes Michigan and Huron, connected by the Straits of Mackinac, rise and fall as a single lake.
Lake Superior was near the upper end of its historical range during the winter, but did not rise as much as usual in April. The level as of May 3, 2018, is about 1 inch (3 centimeters) below its level from a year ago. The IJC’s International Lake Superior Board of Control expects Superior to remain above its long-term average over the next six months, unless conditions are extremely dry. Regulated outflows from Lake Superior have been above average for the past six months and are expected to remain above average through the summer.
Water levels as of May 3 on lakes Michigan and Huron were about 3 inches (7 centimeters) above their level at the same time last year, according to the board. Levels are expected to remain above average over the next six months, even under extremely dry conditions. As of May 3, Lake Erie was about 4 inches (10 centimeters) above its level at the same time last year. It is expected to remain above average over the next six months, even if conditions are extremely dry. Strong winds can vary the level along the Lake Erie shoreline by several feet from one end of the lake to the other, causing short-term flooding and wave damage as seen along the western end of the lake on April 14-15.
Water supplies to Lake Ontario have been above average for more than a year, including record high monthly supplies in May 2017 and February 2018, and the highest-ever two and three consecutive months of supplies from April through June 2017. Regulated outflows have been extremely high throughout this period, including all-time record releases during the summer of 2017. February 2018 outflows were the highest in any February on record.
As of May 3, the Lake Ontario water level was 8.5 inches (22 cm) above average, according to the International Lake Ontario-St. Lawrence River Board, although about 16 inches (41 cm) below its level this time last year. With normal supplies, Lake Ontario is expected to fall toward average by mid-summer and remain near average through the end of the calendar year. Outflows are as high as possible without creating significant flooding in the St. Lawrence River.
With winter here, annual efforts to manage ice flows in the St. Marys, Niagara, and St. Lawrence rivers are in full swing. Management efforts in these connecting channels of the Great Lakes aim to prevent ice jams that can cause winter floods and damage to hydroelectric turbines, while contending with difficult or unexpected winter conditions.
In cold seasons, ice typically forms along the Great Lakes and its connecting channels. Unregulated, this ice can take a while to form a solid layer due to currents, leading broken pieces of ice to jam up and cause flooding.
Control structures are in place for shipping and hydropower needs but hydropower dams and ice booms provide a way to influence how ice forms which in turn helps to prevent flooding and protect equipment.
The St. Lawrence River
Prior to dams being built on the St. Lawrence River, ice jams and winter floods were frequent in sections of the river from Ogdensburg, New York, to Montreal, Quebec, said Gail Faveri, co-secretary of the International Lake Ontario-St. Lawrence River Board. Construction of the Moses-Saunders Dam has allowed water managers on both sides of the St. Lawrence a way to control the amount of water flowing out of the river and thus influence how ice forms above and below the dam. By slowing down the velocity, Faveri said, a solid, stable ice cover forms more easily. As ice ages, it smooths out, allowing water flows to increase again without destabilizing the cover.
“When the ice is forming you can lower the flow and slow the velocity, allowing the ice to form (properly),” Faveri said. “Once it gets established, you can go and allow a higher outflow. It functions more like a pipe … and you can drive more water through.”
The gates at the Iroquois Dam at Iroquois, Ontario, also may be used to promote ice formation upstream.
Power companies also install ice booms around Nov. 20 each year between Prescott, Ontario, and Cardinal, New York, to help ice form upstream, Faveri said. Those are handled by Ontario Power Generation and the New York Power Authority, and the IJC is alerted when the booms are installed. Two main booms that stretch across the main channel of the river remain partially open until the Seaway closes to vessel traffic each winter.
Eastern Lake Erie
Now turning upstream, this season’s Lake Erie-Niagara River ice boom was installed on Dec. 16-17 by the New York Power Authority at the outlet of Lake Erie as it has been every ice season since 1964. The IJC issues approvals to the New York Power Authority and Ontario Power Generation to install the boom to accelerate the formation of a naturally occurring ice arch at the outlet of Lake Erie into the Niagara River, said Derrick Beach, secretary to the International Niagara Board of Control. Conditions for the operation of the ice boom are provided in the IJC’s approval to ensure that potential impacts, like flooding to surrounding residents and activities on the lake and river are minimized. The IJC has appointed the International Niagara Board of Control to oversee that the conditions of the ice boom’s approval are met.
“The ice boom reduces the amount of ice that goes down the Niagara River,” Beach said. “The ice naturally (accumulates) in that area on the lake creating an ice arch and the ice boom helps the formation of that natural ice arch that holds the ice back in Lake Erie.”
Once the ice arch forms, it naturally reduces the amount of ice entering the Niagara River and the potential of the ice jamming or damaging intakes in hydroelectric power plants along the way. As an added benefit, Beach said the ice boom helps prevent ice from jamming in the Niagara River and causing flooding and shoreline property damage along the river. However, as a floating boom, if high winds or thick ice cause a lot of ice to push against it, the boom will be pushed under water and allow some ice to pass, and then float to the surface again after the ice has passed, allowing some natural transport of ice to continue.
The Lake Erie-Niagara River boom consists of about 1.7 miles (2.7 kilometers) of floating pontoons cabled together, and is maintained by the New York Power Authority on behalf of the hydropower generating facilities on the US and Canadian sides of the Niagara River. Some of these conditions include that the boom cannot be installed each year until the water temperature of Lake Erie drops to 39 degrees Fahrenheit (4 degrees Celsius) or on Dec. 16, whichever comes first. As well, the boom’s approval requires that all floating sections be opened by April 1 unless there is more than 650 square kilometers (250 square miles) of ice remaining in the eastern part of Lake Erie. The latest the boom was taken out was May 3, 1971.
The St. Marys River and uncontrolled channels
Hydropower entities install ice booms in the St. Marys River connecting Lakes Superior and Huron to protect their operations, as does the US Army Corps of Engineers to protect a ferry operator, said John Allis, alternate regulation representative with the International Lake Superior Board of Control and Great Lakes Hydraulics and Hydrology office chief for the US Army Corps of Engineers (USACE) Detroit District. At the start of December, the focus of water managers – much as in the St. Lawrence region – is on reducing water flows using its compensating works flow control structure and hydropower operations so that a solid ice cover can form, allowing a consistent water flow the rest of the winter to reduce the chances of ice jams.
“Even if we could chip ice away from the compensating gates to be able to open them up during the winter, we don’t want to drastically change flows month to month, as you could begin to break up the ice cover and getting that ice flowing, causing ice jams,” Allis said.
The connecting channel between Lakes Huron and Erie has no control structures, Allis said, but the USACE and Canadian Hydrographic Service (CHS) monitors ice conditions along the St. Clair and Detroit rivers in the winter months in case of ice jams. The US National Oceanic and Atmospheric Administration and the CHS have gauges along the connecting channels, and when a jam is forming water levels can suddenly decline downstream and increase upstream as the water is backed up. When those instances occur, Allis said the Corps notifies the US Coast Guard so it can send an icebreaker to clear the jam before it can cause a flood event along the shoreline.
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.
Invasive zebra and quagga mussels from the Ponto-Caspian region of Europe began to drastically change the ecosystem of the Great Lakes starting in the late 1980s. Scientists wondered how lake trout would adapt. In Lakes Michigan and Ontario, they’ve found that trout are finding meals by going after invasive fish like the round goby.
Invading species changed the food web of the lakes by eating plankton species and drawing nutrients closer to the nearshore and benthic (the lowest part of the water column) regions, reducing their availability to native fish and zooplankton species. In recent decades, scientists have studied the long-term effects on native species, said Nicole Saavedra, a masters student at the State University of New York’s College of Environmental Science and Forestry who works on lake trout in Lake Ontario.
“On the Ponto-Caspian species invasion, it’s not necessarily all doom-and-gloom,” Saavedra said. “While it has changed things in the lake, specifically species like round goby have provided a food source for lake trout as well as other predatory consumers.”
Lake trout are the top native predator in the Great Lakes, living long lives and hunting a mix of prey species as they grow. Historically, Lake Ontario trout consumed benthic macrointervebrates called Diporeia and sculpins as juveniles, moving over to rainbow smelt, cisco, alewives and other species as adults, Saavedra said. Since the Ponto-Caspian invasion, juvenile lake trout are primarily eating opossum shrimp, or Mysis, while adults are leaning more heavily on alewives and round goby. Lake trout are still growing to lengths researchers have seen historically, she said, but don’t seem to be as fatty or “lipid rich,” which might suggest a link on how they’re acquiring or using energy.
Given that lake trout are a popular fish for anglers and Canadian and US government agencies have been trying to restore their depleted numbers for decades, it’s important to know what their food supply looks like today. Simply looking at what’s in their stomachs only provides a look at a couple days of meals, but pollutants like polychlorinated biphenyls (PCBs) that bind with fat and lipid tissue in the lake trout can help provide a long-term glimpse into the trout’s diet – especially since data goes back to 1977.
The Ontario Ministry of Natural Resources (MNR) Lake Ontario Management Unit has been studying the lake trout population in Lake Ontario’s Canadian waters since 1996 (prior to that point, the trout were monitored binationally in a netting program). According to a 2016 Great Lakes Fishery Commission report released in March, lake trout numbers declined in the lake in the early 1990s following the invasion and reached their nadir in 2005. Since then, more have been gradually caught, albeit numbers are still below the ideal. The Ministry found that alewife is the most consumed food by weight.
Another insight from this research: Saavedra said her colleagues at the USGS survey station in Oswego have found a recent increase in natural reproduction of lake trout, which could be a positive trend for the species and related to the changes in the food web (with younger adult lake trout using round goby as prey).
Saavedra said her study is ongoing and she expects to be finished with her research by the spring of 2018.
Similar work is going on in Lake Michigan, where researchers are investigating the diets of salmonid species – lake trout, Chinook salmon, brown trout, coho salmon and steelhead trout – caught by anglers throughout the lake. Austin Happel, a freshwater ecologist with the Illinois Natural History Survey, said that over 2015 and 2016 they took fish collected from anglers by the US Fish and Wildlife Service’s Great Lakes Mass Marking Program and checked their stomach contents to see what they’d eaten most recently.
They found that round goby are making up a larger share of lake trout diets in Lake Michigan, following a seasonal pattern: goby-heavy diets in the spring and fall when waters are cooler, with more alewives in the summer.
Additionally, like in Lake Ontario, Happel said information from US Fish and Wildlife Service suggests that lake trout seem to be increasing their natural reproduction in Lake Michigan in the southern basin, where high survival of stocked fish has increased parental stock size.
Matthew Kornis, fish biologist with the US Fish and Wildlife Service, said brown trout and lake trout have adjusted to declining populations of preyfish like alewife, sculpin and bloater by hunting and eating other fish, notably the round goby. Pacific salmon are still primarily hunting alewives year-round, and while steelhead salmon are eating more invertebrates, their diets are still alewife-dominated.
“Whether that can be attributed to goby or something else in the food web is still debated quite a bit, but it seems like as alewives are having problems while gobies are expanding. These changes (to the prey base) are coinciding with increases in natural production that is having an effect on the ability of these (salmonids) to reproduce,” Happel said.
Happel said that coincidentally as the round goby population expanded and the alewife population decreased around 2005-2006, Chinook salmon also showed increased signs of natural reproduction, despite not eating gobies. That stable period that lasted until 2013, when Chinook wild reproduction dropped slightly. He said researchers are still trying to determine if any of those prey shifts may have played a role in the increase in wild Chinook spawning.
Researchers studying salmonid diets through stable isotopes are reporting similar results. Kornis said researchers track these non-radioactive variations of carbon and nitrogen as they move through the food web. Stable isotopes from prey can remain in a trout or salmon for up to a year before being fully absorbed into the animal’s tissue, and thus stable isotopes offer a picture of diet over a longer time frame compared to the snapshots provided by evaluating stomach contents. Kornis said they then also can chart what kind of overlap there is on prey among the Pacific salmon species (Chinook salmon, coho salmon, and steelhead), brown trout and lake trout.
“It’s led us to conclude that the competition for the remaining pelagic forage like alewife will be greatest among the Pacific salmon, whereas the trout species are diversifying their diet in response to the prey availability,” Kornis said. He added that this suggests that continued stocking and trout recovery efforts are worth pursuing, as the fish will continue to adjust as the forage base changes.
Since this study targeted only fish that were caught by anglers, Happel said it could be skewing the results to favor certain prey species, such as terrestrial insects for steelhead, lake trout caught in the water column (vs. on bottom) having more alewife, or the stomachs from fish caught closer to shore having more round goby. He said the researchers are looking into whether offshore gillnetting would change the results significantly. Round gobies tend to show up where invasive mussels are, as they are one of the few species in the Great Lakes that preys on the zebra and quagga mussels particularly prevalent in southwestern Lake Michigan near Waukegan – coincidentally the area where lake trout are naturally reproducing most successfully. Conversely, the mussels’ filter feeding on plankton seems to hurt alewives and other preyfish that would otherwise be using those food sources, either directly or indirectly, Happel said.
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.
2017 has been a challenging year for property owners and businesses located along the shoreline of Lake Ontario and the St. Lawrence River. An extremely wet spring led to record high water levels on Lake Ontario and the St. Lawrence River, which resulted in flood and erosion damage to a number of shoreline properties.
The IJC’s Great Lakes-St. Lawrence River Adaptive Management (GLAM) Committee is responsible for gathering information that will support the IJC in its review of the plan for managing the flow of water from Lake Ontario to the St. Lawrence River as undertaken at Cornwall, Ontario, and Massena, New York. Given the extremely high water levels on Lake Ontario and the St. Lawrence River in 2017, the GLAM Committee is seeking input from shoreline property owners and businesses to better understand what happened out there, who and what was impacted, where impacts occurred, and how much damage was caused.
To do this, we are gathering information from a variety of sources. This includes seeking direct input from shoreline property owners. The GLAM Committee is working with Conservation Ontario to conduct an online survey to ensure all impacted shoreline residents and businesses have an opportunity to describe what happened to their properties.
This will complement results from an earlier survey conducted this summer by Cornell University and New York Sea Grant of shoreline properties along the US side of Lake Ontario and the St. Lawrence River. While the focus of the GLAM survey is to capture missing Ontario and Quebec information, owners of New York state properties who did not get an opportunity to respond to the earlier Cornell-Sea Grant survey, or who have more to tell, are welcome to respond. If you have property on Lake Ontario or the St. Lawrence River and you suffered damage as a result of the high water levels this year, we want to hear from you.
The GLAM survey asks a variety of questions on the extent of flooding, erosion, damage to shoreline structures, and related damage to residential and business shoreline properties. There is also an opportunity to upload pictures to document the extent of flooding/erosion impacts on shoreline properties. Adding pictures is optional, but encouraged.
The GLAM Committee will use the survey results along with other information from federal, provincial, state and local sources to summarize the impacts and challenges caused by this year’s record-high water levels on the shores of Lake Ontario and the St. Lawrence River and report the results to the IJC. The information also will be used to improve estimates of potential impacts should similar conditions occur in the future.
The survey is available in English and French at this link. There are about 15-40 questions depending on extent of damage being reported, and the survey should take about 10-25 minutes to complete. Please share this article with anyone you know who has property along Lake Ontario and the St. Lawrence River. The more that people share and contribute, the more we can learn.
Eurasian tench, an invasive species found in Canada and the United States, has been rapidly expanding its range into the St. Lawrence River in recent years. Its upstream spread has reached as far west as Lake St. Francis in southeast Ontario Great Lakes researchers, scientists, and resource managers are concerned the tench could wreak havoc on native fish and their habitat if it enters the Great Lakes.
Tench are native to Europe and western Asia, and were introduced to North America by the U.S. Fish Commission in 1877 for use as a food and sport fish, according to the US Geological Survey. That effort continued into the 20th century, but in most areas where the fish was introduced, it did not become established. However, a population introduced illegally to the Richelieu River by an unlicensed fish farm in 1986 has spread rapidly to the St. Lawrence River and Lake Champlain, according to McGill University Ph.D student Sunci Avlijas, who has studied the tench.
Ever since the fish were first detected in the St. Lawrence River in 2006, Avlijas said, a monitoring program run by the Quebec government and commercial fishermen has been in place. The population has grown exponentially every year between 2009 and 2014. They’ve also spread downstream on the St. Lawrence toward Quebec City and upstream toward Lake Ontario.
“We’re concerned about it moving toward the Great Lakes since the tench prefers slow-moving waters in wetland areas, and there are many such habitats in the Great Lakes,” said Avlijas, whose findings were presented at the International Association for Great Lakes Research conference in June 2017. “(Once) tench enter the Great Lakes there’s the Bay of Quinte, which is even better habitat than we find in the St. Lawrence.”
Once established in an ideal environment, tench form dense populations. Avlijas said tench will eat a variety of macroinvertebrates – zooplankton, mollusks and mussels, insects, and crayfish – mainly from the water bottom, but in calm waters they’ll even go to the surface for food. They also tend to kick up mud and sediment, reducing water quality. Aside from direct competition with native fish for food, tench also carry non-native parasites that aren’t known to be present in the Great Lakes, Avljias said, making them potential disease carriers for native fish. Tench also are known for eating zooplankton that can keep algae in check, potentially worsening the amount and size of harmful algal blooms.
What’s more, they can survive in low-oxygen environments, and cover themselves in mud to survive outside of water for a limited period, allowing them to be introduced into new water bodies, Avlijas said. There have been documented cases of tench being mailed in wet sacks and arriving alive a day later.
“They’re a prime candidate for being transported by people,” she said.
While tench are eaten by native fish like walleye, northern pike, smallmouth bass, largemouth bass and bowfin, once they grow longer than about 12 inches (30 centimeters), they become too large for most predators to consume. Avlijas said this has happened in Lake St. Pierre, where the fish are abundant.
The extent to which tench could impact the Great Lakes is still debated, but it’s predicted they could become established here, said Jeff Brinsmead, senior invasive species biologist with the Ontario Ministry of Natural Resources and Forestry.
While most Great Lakes states don’t ban tench, Wisconsin has a prohibition on the species dating back to when its own invasive species rule went into effect in 2009. Under the rule, the transportation, possession, transfer and introduction of Eurasian tench is illegal in the state. According to Joanne Haas, a Wisconsin Department of Natural Resources public information officer, tench had been stocked in some lakes in the past, and has been known to exist in surrounding states like Ohio, Indiana, Illinois and Michigan – albeit with few reproducing populations. Wisconsin is still concerned about reproductive potential, however, and sees tench as a potential competitor to minnows and native sportfish.
While tench are not regulated as an invasive species in Ontario, rules that apply to all fish species in the province also apply to the tench: a fish can only be released into the water body it was found in unless the releasing person or organization has a license. The use of tench as a baitfish is also illegal in the province, and residents are asked to alert the Ministry of Natural Resources and Forestry if tench are found in the wild by calling the Invading Species Hotline at 1-800-563-7711, or going online to www.EDDMapS/Ontario. Illegal activities involving tench can be reported to the ministry’s enforcement branch at 877-TIPS-MNR (877-847-7667). More information can be found on Ontario’s Invading Species Awareness Program website.
Once an invasive species becomes established in a new environment, it is very difficult, if not impossible, to eradicate. However, it may be possible to slow or block the spread of the species. Education and outreach are critical to ensure that people are aware of the rules that apply to moving live fish. Brinsmead said that since tench are related to Asian carp, it’s possible that similar techniques could be effective in containing the spread of tench, like electric barriers. However, testing specific to tench hasn’t been done yet, and Brinsmead noted that other species – like the endangered American eel – travel through the St. Lawrence River too, so any measures to block tench would need to keep the passage of these species in mind.
Avlijas suggested that to limit the spread, people throughout the lakes follow provincial and state regulations.
“People just consider it non-invasive because after its (legal) introduction it was not spreading,” she said. “It was ignored for a long time.”
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.
By Dr. Michael Izard-Carroll, US Army Corps of Engineers
The US Army Corps of Engineers, Buffalo District, has been active in response efforts to assist New York State communities along Lake Ontario during ongoing historic high water levels. Since Gov. Cuomo’s request for assistance on May 9, 2017, Corps efforts have included direct and technical assistance as part of Public Law 84-99 Response Operations.
Direct assistance has included the distribution of government-furnished materials in the form of 180,000 sandbags, while technical assistance has included Corps personnel deploying to affected areas identified by the New York State Office of Emergency Management.
A total of 20 field visits to 17 affected areas in all eight impacted counties were conducted between May 12 and May 26. The Corps of Engineers Regulatory team also has worked closely with the New York State Department of Environmental Conservation (NYSDEC) to ensure synchronized and streamlined permitting processes for residents seeking to implement shoreline protection measures.
The Corps has been closely monitoring the water level of Lake Ontario and reports indicate water levels have decreased by about 3 feet since levels peaked in late May. In terms of assistance, the Corps has transitioned from emergency assistance to focusing on educating coastal communities about the need for permanent measures to increase coastal resiliency and mitigate future risk to public infrastructure.
Corps planners have met with members of the NYSDEC to discuss options. Any permanent projects would most likely be conducted under the Continuing Authorities Program (CAP), which supports shoreline protection, erosion mitigation or flood risk management.
The Continuing Authorities Program provides the Corps of Engineers with the authority to plan, design and construct water-resource projects in partnership with local sponsors without the need for Congressional authorization. The program decreases the amount of time required for a local community to budget, develop and approve a potential project for construction. CAP allows the Corps to plan and implement smaller, less complex and less costly projects in a more efficient manner.
CAP projects have a feasibility phase followed by a design and implementation phase. For the feasibility phase, the federal government covers half of the cost; the federal contribution is 65 percent for the design and construction phase. The cost-sharing aspect of CAP program is attractive for communities that would have challenges funding these types of projects on their own.
The types of projects under CAP Section 14, Stream Bank and Shoreline Protection and Section 103, Hurricane and Storm Damage Reduction, typically take two to three years for the feasibility study, under a year for design, and one year to construct. Therefore, communities interested in flood prevention measures are encouraged to reach out to the Corps of Engineers as soon as possible. For a brochure on the CAP program, see www.lrb.usace.army.mil/Missions/Civil-Works/Overview/Continuing-Authorities-Program/.
Dr. Michael Izard-Carroll is the public affairs specialist for the US Army Corps of Engineers, Buffalo District.
By Rob Caldwell, International Lake Ontario-St. Lawrence River Board
There has been much speculation and many theories put forth as to what factors contributed to the high-water crisis on Lake Ontario and the St. Lawrence River this year, from rain to snow, water levels and regulation Plan 2014.
The truth is there were many factors. But as a colleague recently summed up, the main ones were “Rain, rain, and more rain!”
Of course, this is an over-simplification, but in retrospect, the high water levels stemmed mainly from four rain-related factors: an unusual mild and wet winter, above-normal inflows from the upper Great Lakes, a record-setting spring freshet in the Ottawa River basin, and heavy rainfalls across the Lake Ontario and the St. Lawrence River system that have continued through spring and early summer.
This unprecedented combination of climate conditions presented the International Lake Ontario-St. Lawrence River Board with a most difficult challenge. Let’s take a closer look at how things unfolded during the first half of 2017, including the factors leading to the record-high levels and how the board has taken into consideration these exceptional conditions in its decision making.
2017 Brings New Plan
On Dec. 8, 2016, the International Joint Commission issued a Supplementary Order, replacing Plan 1958-D and adopting Plan 2014 as the new regulation plan effective Jan. 7, 2017. Plan 2014 prescribes a new set of rules that the board must ordinarily follow in setting the outflows from Lake Ontario through the St. Lawrence River, which are controlled at the Moses-Saunders generating station at Cornwall, Ontario and Massena, New York.
At the time Plan 2014 was implemented, Lake Ontario’s water level was 6 centimeters or 2.4 inches below its long-term (1918-2016) average for that time of year, and at about the same level as each of the past two years. The upper Great Lakes, including Lake Erie, which supplies about 85 percent of the total inflow of water to Lake Ontario via the Niagara River and Welland Canal, were somewhat above average, but not significantly so and also at similar levels to recent years. Finally, at the start of January, ice was already forming on the St. Lawrence River in the Beauharnois Canal (located between Moses-Saunders and the city of Montreal further downstream on the St. Lawrence). The board had already reduced outflows from Lake Ontario to the rate required for ice formation, which applied under the old and new regulation plans, allowing a seamless transition.
A Mild and Wet Winter Season (January to March)
When ice starts forming at critical locations in the St. Lawrence River, outflows must be temporarily reduced to ensure the formation of a safe and stable ice cover. Doing so reduces the risk that the ice cover will collapse or that the fast-moving water will generate what’s known as frazil ice (ice crystals suspended in water that is too turbulent to freeze solid), possibly resulting in an ice jam. Such an occurrence would significantly reduce outflows, causing immediate flooding upstream, and rapidly declining levels downstream. Once a stable ice cover has formed, the board can safely increase outflows.
By Jan. 17, the Beauharnois Canal was half-covered with ice and the unusual winter weather began. Unseasonably mild temperatures combined with a number of heavy precipitation events in January caused much of the precipitation to fall as rain, particularly in the more southerly parts of the basin. Much of the snow that fell also melted with the mild weather, running off into local streams and tributaries, and making its way to Lake Ontario and the St. Lawrence River.
Notably, daily high temperatures were above freezing for about a week straight from Jan. 16-23. With an extensive, prolonged thaw under way, the ice that had formed in the Beauharnois Canal began to disappear, and eventually receded to the point that Lake Ontario outflow was safely increased back to values previously passed during the open-water season. But by Jan. 25, following another period of colder weather, ice had started forming again and the flow was reduced again on Jan. 28. But mild weather returned, and so flow was again increased on Jan. 31.
This cycle of freezing and thawing continued in February, and flows were adjusted six times that month in response to fluctuating temperatures and ice conditions. A few days of typically cold winter weather at the start of February were followed by several days of milder, but below freezing temperatures, allowing ice to form slowly. However, the last half of the month was exceptionally warm: daily high temperatures recorded at Dorval, Quebec, near Beauharnois, were above freezing for 13 straight days from Feb. 18 through March 2 and reached 14.5 Celsius (58 Fahrenheit) on Feb. 25. The ice cover was gone by Feb. 26, and this permitted the board to increase the flow several times by month’s end.
At the same time, water levels throughout the system began to increase gradually as snowmelt and wet weather continued. Lake Ontario rose significantly more than normal in February, as inflows were above average and outflows were restricted by fluctuating ice conditions. St. Lawrence River levels near Montreal also gradually edged upwards until suddenly shooting above average on Feb. 26 as snowmelt combined with rare February thunderstorms and rainfall.
Normally, by February, a solid ice cover has formed on the St. Lawrence River and remains in place, while occasionally, milder temperatures cause the ice cover to melt during this month. Either condition allows flows to be safely increased thereafter. At no time in recorded history had ice begun forming in March, and the board had no reason to believe this year would be any different. But between March 4 and March 30, substantial ice cover formed and disappeared twice in the Beauharnois Canal during what were two of the coldest stretches of weather seen all winter. As a result, Lake Ontario outflows varied considerably, being reduced as ice formed during a good part of the first half of the month, and then increased four times by a total of 18 percent from March 17- 22. Once increased, flows remained relatively stable for the rest of March.
Overall, the winter saw five periods of ice formation punctuated with thaw cycles in between, the most ever seen in the St. Lawrence River.
While highly variable ice conditions restricted outflows at times, the main driver of rising water levels throughout the Lake Ontario-St. Lawrence River system during the first three months of 2017 was the above-normal amount of water the basin received. This water came from precipitation, snowmelt and runoff from within the basin, and above-average and increasing inflows from Lake Erie, which also saw wet conditions and generally rising water levels throughout this period. From January through March, the net total water supply (i.e., total inflow) to Lake Ontario was above average, and the 12th highest for this three-month period since records begin in 1900. At the end of March, water levels were where they were in 2016, and the mid-March 90-day forecasts from Canada and the US suggested average precipitation was expected in April, May and June.
Record Ottawa River freshet (April and May)
The unusual wet winter transitioned quickly to an exceptionally wet spring. Water levels on Lake St. Louis, located on the St. Lawrence River just upstream of Montreal, generally rose quickly throughout the first three weeks of April following a significant thaw event marked by thunderstorms and rainfall. This event, while relatively large, was not entirely unusual; the Ottawa River enters the St. Lawrence at this location and at this time of year snowmelt and rainfall tend to rapidly increase flows out of this large basin. Nonetheless, the peak flow of 6,877 cubic meters per second (242,900 cubic feet per second) on April 20 was a record for this date, and the highest Ottawa River flow since 1998.
From April 1-5, the Plan 2014 rule curve flow was followed. Thereafter, a series of rainstorms passed through the region, with areas to the north and east of Lake Ontario and into the Ottawa and St. Lawrence River basins being particularly hard-hit. This led to two dozen adjustments to Lake Ontario outflows during the month of April in response to the rapidly rising and highly variable Ottawa River and local tributary flows.
These adjustments were done in accordance with the Plan 2014 “F-limit,” which was designed to mimic the board’s decision making strategies under the previous regulation plan, Plan 1958-D, during high-water events in the 1990s (whereby flooding and erosion risks and impacts upstream on Lake Ontario and in the 1000 Islands were balanced with those downstream from Lake St. Louis through Lake St. Peter). During periods of wet spring conditions, as levels on Lake Ontario reach higher and more critical values, this multi-tiered rule also allows increased levels downstream at Lake St. Louis, which acts as somewhat of a barometer for other areas downstream, and Lake Ontario outflows are adjusted accordingly. The total inflow to Lake Ontario during the month of April was the second highest recorded since 1900.
While the wet weather continued, Lake Ontario and St. Lawrence River levels continued to rise, reaching record high levels and resulting in flooding and related impacts throughout the system. Lake Ontario’s end-of-week level reached what is known as the criterion H14 upper trigger level on April 28. Criterion H14 is another rule, again part of Plan 2014, that when exceeded, authorizes the board to follow an alternative strategy and release outflows to provide all possible relief to riparians living along the shorelines of the entire system. There are four upper trigger levels per month (48 per year) and these thresholds can be expected to be exceeded 2 percent of the time, by definition, given historical water supplies. However, at the time, given the exceptional conditions, the board consensus was that the best way to balance the effects of water levels upstream and downstream and minimize flood and erosion impacts to the extent possible throughout the system was to continue to follow the “F-limit” of Plan 2014. As a result, deviations from the plan were not employed.
Unfortunately, as conditions remained critical, the wet weather only worsened in May. The total inflow to Lake Ontario during the month was the highest recorded since 1900. The month began with a so-called “perfect storm.” There were two extremely large and slow-moving storm systems that passed through the region, the first on April 30 and the second from May 4-8. These storms combined to dump a minimum of 75 millimeters or 3 inches of rain over most of the Lake Ontario, Ottawa and St. Lawrence River basins, while some areas around Lake Ontario received twice that amount. Heavy rain also fell upstream of Lake Ontario on Lake Erie, where water levels also were rising and inflows to Lake Ontario increased to well above average values.
As a result, during the first third of May, water flowed into Lake Ontario at record-high rates and about 25 percent higher than any release the board can physically pass down the river. At the same time, the daily mean Ottawa River outflow (at Carillon Dam) peaked at 8,862 m3/s (313,000 cfs) on May 8 – a new all‐time record maximum, which resulted in significant flooding in many parts of the Ottawa River basin, in the Montreal area and in many areas of the St. Lawrence further downstream.
In response, outflows from Lake Ontario were reduced quickly and significantly over the first week of May to moderate the sharp rise in St. Lawrence River levels near Montreal. As Ottawa River flows subsided, the Lake Ontario outflow was increased rapidly, rising from a low of 6,200 m3/s (219,000 cfs) on May 7 to a high of 10,200 m3/s (360,200 cfs) on May 24 (i.e., raised 35 percent in 17 days). In so doing, the board continued to balance upstream and downstream levels according to the “F-limit,” exceeded the Plan 2014 flow and initiated major deviations in accordance with criterion H14 to provide all possible relief to riparians upstream of the dam.
The flow of 10,200 m3/s (360,200 cfs) was equivalent to the record-maximum weekly mean values passed under Plan 1958-DD in 1993 and 1998 and also equivalent to the maximum “L-limit” value, another rule within Plan 2014. This limit defines the maximum outflow that will maintain adequate levels and safe velocities for navigation in the International Section of the St. Lawrence River when Lake Ontario levels are very high – from above 75.70 meters until 76 meters (248.36 feet until 249.34 feet). The St. Lawrence Seaway imposed several mitigation measures to ensure safe vessel transits remained possible.
Despite these record high releases, inflows also remained well above normal seasonal values, and Lake Ontario levels remained high and peaked near the end of May at 75.88 meters or 248.95 feet, a new all-time record value. Montreal area levels, after their rapid rise toward record values throughout the first third of May, generally declined slowly thereafter as Lake Ontario outflows were increased, but Ottawa River outflows decreased at a faster rate.
In total, Lake Ontario outflows were adjusted 23 times in May.
Heavy Rainfalls Continue (June and July)
By June 2, water levels on Lake St. Louis had started to decline. On June 14, the board initiated additional major deviations from Plan 2014 flows, increasing the Lake Ontario outflow to 10,400 m3/s (367,300 cfs). This was a new record-maximum weekly flow, the highest ever released from Lake Ontario. The St. Lawrence Seaway imposed further mitigation measures and undertook an assessment of this higher outflow for several days, concluding that it was the absolute maximum outflow possible to maintain adequate levels and safe velocities for navigation in the International Section of the river. After some deliberation regarding the impacts of increasing the outflows further, the board decided to maintain this outflow for the remainder of the month and into July.
The monthly mean outflow from Lake Ontario in June averaged 10,310 m3/s (364,100 cfs), 38 percent above the June long-term average (1900-2016) and a new record-high value for any month, exceeding the previous record of 10,010 m3/s (353,500 cfs) set in May and June of 1993.
Wet weather continued in June. A particularly noteworthy storm on June 23 dropped 20.5 mm or 0.8 inches of rain on the Lake Ontario basin. After gradually declining for most of the month, Lake Ontario levels rose slightly as a result. The total inflow to Lake Ontario during the month was the second highest recorded in June since 1900. Nonetheless, the record-high outflows allowed Lake Ontario levels to fall 9 cm or 3.5 inches overall in June – much more than the typical 1 cm or 0.4 inch decline, and the 11th highest June decline on record. By the end of June, Lake Ontario was 10 cm or 3.9 inches below the peak level recorded on May 29. About 6.6 cm or 2.6 inches of that water was removed from Lake Ontario, owing to major deviations undertaken since May 23. The remainder was due to high outflows prescribed by Plan 2014 and the fact that inflows, while still high, had begun to decline.
Montreal area levels generally fell through the middle of June as Ottawa River outflows declined, but rose slightly at the end of June and even further during the first week of July, reaching high levels and flooding similar to that seen earlier in the spring.
The board agreed to continue releasing 10,400 m3/s (367,300 cfs) into July. Despite these efforts, the continuing wet conditions sustained the high levels and severe impacts to Lake Ontario and St. Lawrence River property owners, recreational boaters, businesses and tourism. Lake Erie remained well above average, and combined with significant rainfall during the past month, the total inflow to Lake Ontario remained high.
Decisions and the Path Forward
The first several months of 2017 have been an especially challenging time for those living and working throughout the Lake Ontario-St. Lawrence River system. Many have been impacted by the exceptionally high water levels. While levels have begun to decline, the effects continue to be felt and may continue for months to come.
For its part, the board has made every effort to address the exceptional weather conditions and reduce levels to the extent possible. Outflows were continuously adjusted from January through March during what was a generally wet winter, with highly variable temperatures and challenging ice conditions. As the weather turned from bad to worse, the board continued to adjust outflows in April and May, this time to address the extreme precipitation, record inflows and rapidly rising water levels which have caused severe flooding and associated impacts throughout the system. Since then, the board has increased outflows to record-high values in an attempt to lower the extraordinary levels of Lake Ontario and provide relief to those impacted, while also considering the impacts to riparian interests downstream on the St. Lawrence, and to other stakeholders, including commercial navigation and the industries it supports.
Despite these efforts, wet weather has continued and levels have remained high. There are unfortunately no simple solutions, but the board will continue to consider all possible options, as well as associated impacts, in setting outflows from Lake Ontario. High outflows are expected to continue for several weeks, and as warmer and drier summer conditions continue and evaporation rates increase into the fall. The board expects water levels throughout the system will generally continue to decline, providing gradual relief from the high water crisis of 2017. But keep in mind that water levels may remain above normal for some time to come, and autumn brings a higher chance of damaging storms. Strong winds and wave action can cause significant fluctuations on the lake and river, with temporary changes of more than half a meter (2 feet) in certain locations.
By Arun Heer, International Lake Ontario-St. Lawrence River Board
Since the establishment of the International Lake Ontario-St. Lawrence River Board by the International Joint Commission in 1952, keeping people informed about water level and flow conditions in the lake and river has been a top priority. With the Lake Ontario-St. Lawrence River basin covering such a broad geographic area, including communities in New York, and the provinces of Ontario and Quebec, communication has often been challenging and resource intensive. In the past, the board relied on methods such as in-person public meetings, telephone conferences, and mailing news releases and hard-copy letters to connect with people.
Today, the board is reaching out with modern communication tools such as Facebook, webpages, electronic mailing lists, animated videos, and digital press releases to deliver messages quickly. The board’s Facebook page, in particular, has proven to be a great forum for posting information on topics such as water levels, outflow changes and hydrologic forecasts.
The Facebook page had close to 800 “likes” in January, and that number had increased to more than 2,300 as of July 24. Facebook has become a place where the board can interact with the community in real-time, and where members of the public can interact with one another to share and exchange information.
The board encourages everyone to visit its Facebook page for the most up-to-date information on board activities and join the conversation. Additionally, short educational videos, media releases, and other information can be found on the board’s website.
Arun Heer is US secretary for the International Lake Ontario-St. Lawrence River Board and co-chair for the Great Lakes-St. Lawrence River Adaptive Management Committee.
Rob Caldwell is the Canadian regulation representative of the International Lake Ontario-St. Lawrence River Board, and provides technical support and advice to the board from his office in Cornwall, Ontario.
An invader in a massive freshwater basin. An uncountable number of spawning grounds. A fishery on the brink. A desperate search for a solution that ended up becoming the most successful aquatic invasive species control team effort in American and Canadian history. It’s not a movie, but rather the true tale of the sea lamprey’s invasion of the Great Lakes.
The sea lamprey is parasitic fish native to the Atlantic Ocean. As an adult, it latches onto other fish with its suction cup-like mouth, using a rasping tongue to cut into its victim to suck out bodily fluids and blood. In the Atlantic it doesn’t typically kill its hosts, but the fish in the Great Lakes have no such luck. It’s estimated that a single lamprey can destroy an average of 18 kilograms (39 pounds) of fish in its parasitic lifetime, with only about one in seven fish surviving a lamprey attack. It’s not to be confused with native lamprey, which are smaller and have different coloration, and don’t usually kill the host fish.
Sea lampreys were first detected in Lake Ontario in 1835. While there has been discussion on whether it is native to Lake Ontario, it most likely is an invasive species that entered through the Erie Canal, according to Marc Gaden, communications director for the Great Lakes Fishery Commission (GLFC), a binational organization funded by the Canadian and US governments. The 1919 reconstruction of the Welland Canal, which bypasses Niagara Falls to connect Lake Ontario to Lake Erie, likely allowed the sea lamprey to enter Lake Erie and on to the rest of the basin. They were discovered in Lake Erie in 1921, Lake Michigan in 1936, Lake Huron in 1937 and Lake Superior in 1939. The sea lamprey found an immense number of tributaries featuring the combination of rocky nesting grounds to lay eggs and silt for larval lampreys to grow in, making the Great Lakes a lamprey Eden. In its native habitat, the sea lamprey spends most of its life in saltwater, making it the rare species that has adapted to living entirely in freshwater systems like the Great Lakes, similar to the Pacific salmon species introduced to control invasive alewives.
The impact on the Great Lakes fishery was devastating. Prior to the invasion, about 20 million pounds or about 9 million kilograms of fish were harvested commercially each year in the upper Great Lakes – Superior, Huron and Michigan. By the 1960s that amount was reduced to about 300,000 pounds (136,077 kg) per year, while sea lamprey were killing close to 100 million pounds (45.4 million kg) of fish each year, and 85 percent of the remaining fish were scarred with lamprey attack wounds.
“Commercial fishermen and fishery managers first realized they had a problem around 1940, when it became clear what was happening to the Huron-Michigan fisheries from lamprey,” Gaden said. “That’s when the managers and scientists went into high gear and started seeking control measures.”
With little experience with aquatic invasive species, a wide variety of control methods were attempted. These methods included physical barriers to keep lamprey from entering the streams they use to spawn, crude electrical barriers to block their advances and sieves to stop larvae from eventually entering the Great Lakes from those inland streams. Entrepreneurs tried to make sea lamprey a commercially fished species for human consumption, but none of these attempts worked in stopping the sea lamprey.
The breakthrough came after years of searching for a chemical compound that would kill sea lamprey and not harm other organisms. A compound called TFM was discovered and field-tested in 1957, and entered management usage in 1958 through the binational GLFC. It has been used to great success.
The lampricide targets larval sea lampreys living in streams. After hatching from eggs found upstream in rocky areas, larvae make their way to silty areas and burrow into the substrate until they emerge as adults. The lampricide kills them in that weak, larval state by disrupting their metabolism before they can ever grow up to become the top predator in the Great Lakes. After decades of use, Gaden said the sea lamprey population in the Great Lakes has been reduced by about 90-95 percent from their peak in the late 1950s, and dropped the amount of fish killed by the lamprey to about 10 million pounds (4.5 million kg) a year. While it also affects native lamprey species, sea lamprey larvae tend to live and spawn in different areas from the native species; fishery managers focus on those stream areas where sea lamprey larvae burrow to minimize the impact on native species.
Lampricide isn’t the only tool used to control lamprey numbers, Gaden said, as good pest control takes multiple tacks. Physical barriers are still in use to deny lampreys a path to their preferred spawning grounds. And if those lampreys can’t reach a place to spawn, there’s no need use lampricide treatments, which is expensive and time-consuming. The GLFC also deploys traps to catch lamprey entering or leaving the streams to remove them from the system, and has tested sterilizing male lamprey in the St. Marys River to try and overwhelm the number of fertile males. Most recently, Gaden said the GLFC “is on the cusp” of using isolated lamprey pheromones to affect their behavior – drawing lamprey away from ideal spawning locations and toward traps.
“We’re working on unlocking their genome,” Gaden said. “There are things within the lamprey genome we can exploit, like create conditions so they only produce males, but that’s further into the future.”
“They deserve a lot of praise for the progress they have made in combatting this destructive invasive species, and I look forward to the GLFC forging another 10-fold decrease in lamprey numbers at some point in the future,” Burrows said.
While a focused and targeted approach to invasive species can work in smaller inland lakes, the size of the Great Lakes makes controlling aquatic invaders difficult. That they invaded a waterway that also serves as a border between Canada and the United States added an additional wrinkle. It meant both countries needed to work together, even though fishery management is primarily the domain of state, province, tribal and First Nation governments. This team effort has kept sea lamprey from completely dominating the ecosystem of the Great Lakes for decades.
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.
While each lake is unique, they all tend to follow a similar cycle based on seasonal changes. Water levels typically reach their seasonal low during the winter months before increasing in the spring due to snowmelt and precipitation. Water levels tend to peak during the summer months, before beginning to drop in the fall and early winter.
There are three main factors that impact lake water levels, said Drew Gronewold, physical scientist with NOAA’s Great Lakes Environmental Research Laboratory: the precipitation over the lakes, evaporation of water on the lakes into vapor, and the runoff that comes into the lakes.
These variables, in turn, are affected by changes in air and water temperatures. For example, Gronewold said the timing of big runoff pulses is dependent on the amount of snow building up in the winter months and when it melts in the spring.
A water level decline in the fall is generally driven by evaporation, as air temperatures drop while surface water temperatures are still relatively warm. While water temperatures were relatively warm during the fall and winter months of 2016-2017 – leading to a lack of ice cover – evaporation amounts have been typical for this time of year due to a relatively mild winter air temperatures, Gronewold said.
These recent conditions, coupled with historical data, lead agencies to expect the water level rise to remain fairly typical this spring and into the summer. As water levels are already above their long-term average for this time of year, researchers expect that they’ll remain above average in the coming months, Gronewold explained.
There is still plenty of uncertainty, he added, as the amount of snow on the ground is less than it has been in some recent winters. It’s also difficult to predict continental-wide meteorological and climate patterns that impact Great Lakes weather patterns and temperatures. These can range from an El Niño effect like the one seen in the winter of 2015-2016 or a “polar vortex” that hit the region in the winters of 2013-2014 and 2014-2015. This uncertainty is expressed as a range of possible water levels in the forecasts released by the US Army Corps and Fisheries and Oceans Canada.
Great Lakes water levels also can be influenced by human management. Hydropower plants and a gated dam on the St. Marys River are used to manage outflows from Lake Superior into Lake Michigan-Huron, while a hydropower plant on the St. Lawrence River is used to manage outflows from Lake Ontario. Outflows through these structures are managed binationally by boards and according to orders and criteria established by the IJC. Nonetheless, the control of water flows through these lakes is limited, and weather conditions and water supplies remain the most significant factor affecting water levels.
Water levels are measured based on the International Great Lakes Datum, defined as the height above sea level at Rimouski Quebec on the St. Lawrence River. Agencies have been measuring lake levels since the 1860s, with more reliable levels going back as far as 1918. They base the lakes’ long-term average water levels on that information.
“We expect a range of water level conditions depending on water supplies,” said Jacob Bruxer, senior water resources engineer with Environment and Climate Change Canada. “There’s a lot of variability and uncertainty in weather and water supply forecasts, particularly when looking beyond a few weeks’ time, so we don’t try to forecast any specific trends and instead consider a full range of water supply scenarios that could be expected.”
According to recent forecasts, through September 2017 Lake Superior is likely to remain at or above seasonal averages, with a small chance of falling below its long-term average in July. There is less uncertainty for the spring months; water levels were about 5.5 inches (0.14 meters) above the long-term average by the end of March, and by May that range could be between 2.7 inches to 10 inches above the average (0.07 meters to 0.27 meters). By September, water levels could be as high as 1 foot (0.3 meters) above the long-term monthly average for Superior.
Lake Michigan-Huron, considered as one lake hydrologically, was about 9.4 inches (0.24 meters) above the March long-term average by the end of the month. By September, Michigan-Huron is expected to remain above the long-term average, in a range of 1-16 inches (0.02-0.4 meters). Gronewold said Michigan-Huron saw water levels fall slightly more during the fall months of 2016 than is typical, but that is unlikely to make a discernible difference during this spring and summer.
Higher-than-average water levels are anticipated on Lake Erie, which has seen water levels on the rise in recent months, reaching more than 17 inches (0.44 meters) above the long-term average by the end of March. Water levels are expected to continue to remain above average this spring, before starting to fall around June to a range of 3.9-16 inches above average (0.10-0.41 meters).
Lake Ontario has a slight chance of being just barely below its long-term average going into summer, but will more likely be above it by up to 15 inches (0.38 meters). The forecasted peak is in May, when water levels could be 3.9-21 inches above average (0.10-0.55 meters). Water levels are then expected to fall at about the same degree as they usually do, according to the long-term average.
The US Army Corps publishes 12-month forecasts for Lakes Erie, Huron-Michigan and Superior, as well as Lake St. Clair, based on current conditions and similar historical weather data. Uncertainty grows substantially more than six months out, but most outcomes for Lakes Erie and Michigan-Huron suggest a greater likelihood of continued higher-than-average water levels through the year. Lake Superior also has a better chance of higher-than-average water levels, but faces a substantial possibility of being below that long-term average, too.
By Jacob Bruxer, International Lake Ontario-St. Lawrence River Board
A series of storm events passed through the Lake Ontario-St. Lawrence River system from April 4-10, resulting in significant precipitation across the region. Some eastern parts of the Lake Ontario basin received as much as 80 millimeters (3.2 inches), while areas around the St. Lawrence River near Montreal saw as much as 90 mm (3.5 inches) during the same series of events.
With the ground already fully saturated, the recent rain, coupled with snowmelt in some areas, resulted in high amounts of runoff and rapidly increasing streamflows across the basin. Flood warnings were issued by many agencies in Canada and the US, and many reports of localized flooding have since been received.
The wet conditions have resulted in rapidly rising water levels throughout the Lake Ontario and St. Lawrence River system. Lake Ontario’s level has risen approximately 19 centimeters (7.5 inches) since April 4, increasing the risk of storm damages and leading to concerns among many lake riparians.
Downstream of Lake Ontario on the St. Lawrence River, levels at Lake St. Louis near Montreal, Quebec, have risen almost twice that amount during the same period, by about 37 centimeters (14.6 inches), due to rapidly rising Ottawa River and other local tributary flows. To prevent Lake St. Louis levels from rising further and causing more extensive damage, the International Lake Ontario-St. Lawrence River Board reduced outflows from Lake Ontario in accordance with Plan 2014, in effect since January.
Plan 2014 sets flows to balance the risk of flood damages, both on Lake Ontario and the St. Lawrence River downstream, by keeping the level of Lake St. Louis below a given threshold for a corresponding Lake Ontario level. As the level of Lake Ontario rises, the threshold level on Lake St. Louis also rises, allowing more water to be released from Lake Ontario.
However, it’s important to note that while Plan 2014 tries to balance these impacts, it cannot and does not eliminate the risk that high levels may occur during periods of extreme weather like we’ve experienced recently. In fact, no regulation plan can do so.
To illustrate the limitations of regulation, consider that it would have taken an increase in outflow of more than 6,000 cubic meters per second (211,900 cubic feet per second) above the average flow since April 4 of 7,010 cubic meters per second (247,600 cubic feet per second) to have maintained Lake Ontario at a stable level. A flow increase of that magnitude would be nearly impossible to achieve, physically. It also would cause levels at Lake St. Louis to rise more than 1 m (3 feet), resulting in catastrophic flooding throughout the lower St. Lawrence River.
Extremely high water levels are a concern to all riparians throughout the Lake Ontario-St. Lawrence River system. While impossible to avoid entirely, balancing the risk of high levels and associate impacts, both upstream and downstream, is a key aspect of Plan 2014.
Jacob Bruxer is the alternate regulation representative of the International Lake Ontario-St. Lawrence River Board and senior water resources engineer at the Great Lakes-St. Lawrence Regulation Office, Environment and Climate Change Canada, Cornwall, Ontario.