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.
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.