By Wendy Leger and Arun Heer, Great Lakes-St. Lawrence Adaptive Management Committee
The complex task of managing water levels and flows in the Great Lakes- St. Lawrence River system has received considerable attention recently following two notable regulatory changes and a series of unprecedented hydrologic events. Together, this presents a significant challenge and an important opportunity for the Great Lakes-St. Lawrence River Adaptive Management (GLAM) Committee.
In January 2015, the International Joint Commission (IJC) implemented regulation Plan 2012, a new set of rules governing the amount of water to release from Lake Superior through the St. Marys River.
More recently, with the concurrence of the U.S and Canadian governments, the IJC implemented Plan 2014 in January 2017 for the regulation of outflows from Lake Ontario through the St. Lawrence River.
Both regulation plans were implemented following years of studies that looked at the impacts of past, present and potential future weather and climate conditions on water levels and outflow regulation, and how these factors affect socio-economic and environmental outcomes throughout the Great Lakes system.
For the various interests and stakeholders that rely on this important resource, as well as the governments, IJC and its management boards, there is a shared desire to know if the expected outcomes of these new regulation plans are being realized under recently observed hydrologic conditions and whether the plans will continue to function as expected and as conditions within the basin change.
To that end, the IJC and governments made a bold commitment to adaptive management with the establishment of a binational, 16-member, GLAM Committee in January 2015. The committee reports to the IJC’s three Great Lakes water level boards and is directed by the IJC to provide an ongoing assessment of regulation plans and examine how these plans perform under a range of actual and potential future hydrologic conditions.
The committee’s primary responsibility is to assess how well currently available scientific data, information, models and tools reflect real world conditions so that improvements and updates can be made as our understanding of the system evolves.
The GLAM Committee will use information provided by government agencies, academic researchers and key stakeholders. It will coordinate the modeling and analysis necessary to assist IJC boards with evaluating the effectiveness of existing regulation plans in managing water levels and flows over the long term and under a range of continually changing conditions.
While the committee is still in its infancy, the importance of the adaptive management process has been quickly demonstrated through a series of extraordinary events within the Great Lakes basin during the past few years. More than a decade of below-average water levels in the upper Great Lakes culminated in record-low levels on Lake Michigan-Huron in January 2013. This prolonged dry period was followed by much wetter conditions. Over the following 24 months, Lake Superior and Lake Michigan-Huron experienced some of the most rapid rates of water level rise on the Great Lakes in recorded history. More recently, extraordinary climatic conditions including significant rainfall across the Lake Ontario, the Ottawa River and the St. Lawrence River basins resulted in record high water levels in 2017 (See “Extreme Conditions and Challenges During High Water Levels on Lake Ontario and the St. Lawrence River”).
These events have had widespread and highly varied impacts. Concerns from stakeholders related to the impacts of low-water on navigation, recreational boating, and coastal wetlands shifted to concerns related to shoreline erosion, minor flooding and modified aquatic habitat conditions in the St. Marys River as upper Great Lakes water levels and outflows increased. On Lake Ontario and the St. Lawrence River, severe flooding and coastal damages have occurred following the exceptional weather conditions this year.
The GLAM Committee is reaching out to multiple agencies and partners to identify data and tools available to analyze and document outcomes from these events throughout the Great Lakes- St. Lawrence River system and sectors covering coastal interests, recreational boating and tourism, commercial navigation, hydropower generation, municipal and industrial water uses as well as ecosystem indicators including wetland habitat response.
During the past year, the committee supported the development of an integrated ecological response model of the St. Marys Rapids to help better understand and predict the effects of changing flows and water levels on fish and other aquatic habitat conditions within this critical area of the upper Great Lakes system. The model will support the evaluation of improved and more efficient gate operations of the dam situated above the rapids.
For Lake Ontario and the St. Lawrence River, this year the committee is focused on documenting, to the extent possible, the overall hydrological and climatic conditions across the basin, as well as the impacts across all sectors. This includes using surveys and shoreline imagery to look at flooding and erosion as well as damages to shore protection and shoreline infrastructure experienced along the Lake Ontario shoreline and St. Lawrence River from Kingston downstream past Montreal.
The committee also is trying to better understand the impacts to recreational boaters and cruise ships that have had to deal with inaccessible docks and boat ramps, closure of marinas and other businesses and reduced tourism revenue. At the same time, the commercial navigation industry has employed mitigation measures to ensure continued safe navigation during a period of record high outflows and increased velocities in the St. Lawrence River, the costs of which the GLAM Committee will investigate. The committee also plans to conduct field surveys of wetland plant response during this high water level year.
A few years provides only a small sample of what future water supply conditions might be like and how various interests are affected, and as a result are insufficient to fully assess the performance of a regulation plan. Nonetheless, the information gathered by the GLAM committee and through other agencies and stakeholders will be used to help inform the IJC, its boards and governments on the overall long-term performance of Plan 2012 and Plan 2014and will more immediately serve to validate and improve the models and tools used to assess regulation plan outcomes, with the aim at improving performance as more is learned and as conditions change.
This is the essence of a collaborative adaptive management process: continued monitoring and assessment to test assumptions, improve methods and determine if regulation plans are meeting expectations and will continue to do so under changing conditions.
Wendy Leger is Canadian co-chair of the GLAM Committee.
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.
To help Great Lakes-St. Lawrence River communities document the impact of record-breaking water levels, New York Sea Grant awarded rapid response funding to Cornell University to develop and conduct high water impact surveys.
The data will be used to identify the types of impact and most vulnerable areas to flooding events. Reporting of results will be on combined measures and will not identify individual addresses.
“This survey effort is in response to stakeholder requests for a standardized method to collect, report, and document the impacts of high water levels on waterfront properties, including erosion, damage to natural and manmade shoreline protective features, and business disruption,” said Mary Austerman, a coastal community development specialist with New York Sea Grant.
Austerman is collaborating on the surveys with Cornell University Assistant Professor of Biological and Environmental Engineering Dr. Scott Steinschneider and Cornell University Professor of Natural Resources Dr. Richard C. Stedman.
Residents of the Sodus Bay area along the southern shore of Lake Ontario pilot tested the survey.
New York Sea Grant is a cooperative program of Cornell University and the State University of New York, and one of 33 university-based programs under the National Sea Grant College Program of the US National Oceanic and Atmospheric Administration. New York Sea Grant maintains Great Lakes regional offices in Buffalo, Newark and Oswego.
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.
Forecasting agencies in the United States and Canada expect Great Lakes water levels to remain near or above their long-term average for the next six months.
Water levels are measured on the International Great Lakes Datum, defined as the height above sea level at Rimouski Quebec on the St. Lawrence River estuary. According to the coordinated, binational forecast at the beginning of July, Lake Superior is expected to remain about 6 inches, or 15.4 centimeters, above its long-term average for this time of year through the summer, before falling closer to average levels in the fall. While this forecast is based on normal weather conditions in coming months, lake levels could be higher or lower depending on whether we have a wetter or drier than normal summer and fall. Long-term averages are based on data going back to 1918.
Lake Michigan-Huron, which have a common level due to their connection at the Straits of Mackinac, is expected to be 10-12 inches (30.8 cm) above average in the summer before falling closer to average in the fall. Lake Erie also is expected to be within 1 foot above average in the summer before ending closer to 8 inches, or 20.32 cm, above average in the fall. Lake Ontario’s July level is 1 inch (2.54 cm) below average for this time of year and is expected to remain close to average in the fall.
Jacob Bruxer, Environment and Climate Change Canada senior water resources engineer, said Lake Ontario’s comparatively lower water levels are due to the warm, dry weather conditions around the lake that started around March. Bruxer is also a member of the IJC’s International Lake Superior Board of Control and the Great Lakes-St. Lawrence River Adaptive Management Committee.
“Those conditions would be bad if we started at average levels, but we’re right around average,” Bruxer said. “We’re not seeing any significant concerns to shipping or recreational boaters.”
The higher water levels on Superior, Michigan-Huron and Erie mean some boat launches could be underwater and beaches are smaller than they would be with lower levels. On the flip side, boaters should have plenty of depth to get their boats into their docks, and anglers may find more coastal areas to fish than they would otherwise. Bruxer added that high levels can lead to greater erosion along bluffs and shorelines due to waves and storms.
Drew Gronewold, a hydrologist at the Great Lakes Environmental Research Laboratory in Ann Arbor, Michigan, explained that the Great Lakes typically follow a seasonal cycle where water levels rise in the spring from runoff and peak in early summer. The lakes then fall in the autumn and winter months as evaporation — caused by temperature differences between the warm water and cool air — picks up, reaching their lowest point around January and February.
As of mid-July, Gronewold said there’s no indication that the autumn dip will be stronger than usual in the lakes, or that water levels will increase – something that occurred in the autumn and winters of 2013 and 2014 on Lake Michigan-Huron and Lake Superior. Bruxer said the lakes are expected to remain either near or slightly above seasonal averages for the foreseeable future.
Coordinated six-month forecasts of Great Lakes water levels are published online each month by the US Army Corps of Engineers and Environment and Climate Change Canada (via the Canadian Hydrographic Service). The US National Oceanic and Atmospheric Administration (NOAA) also provides these forecasts on its water level online viewer each month. Forecasted water levels are determined using binational data and several different models that account for possible variations in evaporation, precipitation and runoff on the lakes over the coming months.
Lauren Fry, civil engineer with the Corps, said the model provides potential outcomes given climatic scenarios, developed based on current conditions and similar existing historical weather data. For example, with the strong El Niño cycling over the past winter, Fry said the agency used data from similarly strong 1982 and 1997 El Niño events to determine a range of potential lake level impacts from October 2015 until September 2016. The most recent one-year outlook from April suggests higher-than-average water levels will most likely continue until April 2017.
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.
The IJC is responsible for regulating outflows from Lake Superior and Lake Ontario affecting water levels and flows in the Great Lakes and St. Lawrence River. In 2015, it established a Great Lakes-St. Lawrence River Adaptive Management Committee, known as GLAM, to provide ongoing monitoring and assessment of these regulated outflows.
Adaptive management is another way of saying that we adjust water resource policies based on hard evidence about the how well they’re working. While people may agree conceptually on the value of adaptive management, it is difficult to do and there are few examples of its full implementation.
Water levels affect stakeholders on the Great Lakes-St. Lawrence River system differently. High water levels can cause flooding and erosion to shoreline properties, but be beneficial for recreational boaters, commercial navigation and hydropower.
Low water levels can leave docks and boat launches high and dry and force big ships to carry less cargo, but low levels also can be beneficial for beach goers. Variability in water levels over time is natural and can improve certain environmental outcomes such as wetland plant diversity. The IJC has to consider all these stakeholders as well as the ecosystem as it regulates the outflows of Lake Superior and Lake Ontario.
Over the last several decades, persistent high or low water levels have triggered multi-year binational studies to determine what can be done about the problems extreme levels cause. These studies have produced better regulation plans and models and data that support those new approaches. Traditionally, when these studies end, there is no follow-up mechanism to measure how effective the new management measures are, and no way to reconsider those measures as preferences change over time and new data becomes available. GLAM is designed to be that mechanism.
GLAM is supported by federal, state and provincial water agencies from both sides of the Canadian-US border. The committee does several things. It maintains and improves the models and databases developed in the studies so they can be used continuously. GLAM also is designing and executing monitoring programs with partner agencies to validate and improve specific parts of the decision support models, where sensitivity analyses showed the recommendations might change if these model elements were improved based on additional data.
GLAM is connecting people so that a wide range of decision makers can learn about developing information sooner and can act on it more expeditiously. GLAM is monitoring climate changes, starting with an effort to reduce errors in water flow and level estimates so that small trends can be identified with greater confidence. GLAM also is developing a sustainable capacity within the agencies to carry this work into the future, making sure young professionals learn from the teams formed during the big studies on water levels and flows. And because there are so few examples, GLAM is reaching out to others to share experiences in managing adaptively, helping to make a good idea practical.
By Ankita Mandelia
Sea Grant Fellow
IJC Great Lakes Regional Office, Windsor, Ontario
To assess progress toward improving water quality, scientists use ecosystem indicators to measure whether things are getting better, worse, or staying the same.
The IJC’s Great Lakes Science Advisory Board is completing a process to identify a subset of 16 indicators that can be used to communicate progress toward improving the health of the Great Lakes. That list is pared down further to eight indicators – the fewest that tell us the most – that address biological, chemical and physical integrity:
How can examining these indicators provide useful information on how the Great Lakes are doing?
Take, for example, chemicals of mutual concern in water. This indicator measures the concentrations of legacy chemicals such as polychlorinated biphenyl compounds (PCBs), mercury, and flame retardants.
Concentrations of these chemicals in water are measured at strategic locations on regular time intervals within the basin. From the measured data, trends and patterns can be determined; such as whether the presence of a chemical is increasing or decreasing over time; or if the chemical is more highly concentrated in the water closer to or further away from land.
These chemicals of mutual concern in water matter because their concentration can give us insight as to where chemicals in an ecosystem came from and where they are headed. Models can be used to help pinpoint if a particular chemical is coming into the lake from a local or a global source, which occurs when contaminants are transported through the atmosphere.
For example, in Lake Erie, we know that relatively local sources (tributaries) are responsible for much of the pollution in the lake. We know that Lake Superior tends to be affected more by global pollutants transported through the atmosphere. Models also can be used to estimate what chemical concentrations might be in endpoints such as drinking water and fish, which are consumed by humans and other animals. Ultimately, this information is useful for telling people if the lake (or areas of the lake) is safe for drinking, swimming, and fishing, and whether or not the status is improving over time.
Figures 1 and 2 provide information on mercury in the Great Lakes. Mercury is on the two governments’ proposed list of Chemicals of Mutual Concern. In the upper Great Lakes, the source of mercury is precipitation; in the lower lakes, the source of mercury is industrial activity and watershed runoff.
This is one example of the Board’s work on how to communicate the indicators of Great Lakes health. The Board’s report on this study will be available on the IJC website in the coming weeks.
The IJC’s role under the Great Lakes Water Quality Agreement is to analyze information provided by the governments, assess the effectiveness of programs in both countries and report on progress toward meeting the Agreement’s objectives.