Watershed hydrology and ecology research

Algae feed on the nutrients, growing and spreading into what are called blooms. The blooms may turn the water green, cause a scum on the surface of the water, or form large mats of slimy or stringy algae attached to rocks, wood or docks. Algae blooms can smell bad, block the sun, and may even release toxins.

Dead mats of algae can also produce bad smells, discourage swimming, and clog water intake pipes. Eventually, the algal mats are decomposed by bacteria that consume oxygen in the water needed by fish and other aquatic life. If enough oxygen is consumed, fish can die.

Scientists have been studying nutrients in freshwaters since the 1960s in response to a serious decline of important waterbodies such as the Great Lakes. In the 1970s, laws were made that lowered phosphorus in laundry detergents and wastewater treatment plant effluent which was important in reducing nutrient pollution and eutrophication not only in the Great Lakes, but in waterbodies around the world.

New challenges have emerged today that threaten to stop or in some cases reverse that progress. Changes in precipitation and runoff patterns due to extreme weather events, alteration of nutrient and energy flows in aquatic food webs due to invasive species are examples of some of the new challenges facing the science community in the 21st century.

New approaches

There are many questions about where nutrients come from and how they affect the environment. To answer these questions, our scientists have turned to new technologies including data sensors and sample collectors. These new approaches allow researchers to better understand how ecosystems respond to nutrient pollution.

Traditionally, studying a nutrient problem involved collecting a sample of water in a container and analyzing the chemical nutrients in a laboratory. Previously, collection was often only possible under “fair” weather conditions or over a shorter period. Now, thanks to new technology, scientists are able to use autonomous data sensors and sample collectors in any weather. Scientists are using this technology to help combat nutrient pollution on Lake Erie and Lake Ontario.

• Learn more about our Environment and Climate Change research.

If you are interested in data, visit the Hamilton Harbour Water Quality Data set.

The phosphate sensor is deployed in surface water to collect long-term phosphate data. It is about 55 cm tall and consists of three colour-coded cartridges holding chemicals which, when added to sample water, develop colour. An onboard optical sensor then scans the sample and calculates the phosphate concentration.

For more information on freshwater nutrients monitoring, you can consult the Water Quality Monitoring and Surveillance program.

Eutrophication is what scientists use to describes the changes to a lake that occur because it has more nutrients than it needs. When rivers or lakes have an overabundance of nutrients, it stimulates the growth of algae. This can typically be seen as “green” lakes. Most often, excess nutrients are caused by fertilizer runoff, livestock manure, or waste treatment plants.

Overgrowth of algae often occurs as “blooms” in the late summer. When these blooms wash onshore it can cause unpleasant smells and can degrade the natural beauty of beaches on lakes. In addition to the smells, some blue green algae can produce toxins that are hazardous to human and animal health. This is what is happening in Lake Winnipeg and is responsible for increasingly large algal blooms in recent years.

What are stable isotopes?

Stable Isotopes are naturally occurring atoms that have stable cores and do not emit radiation. The most commonly analyzed stable isotopes are oxygen, carbon, nitrogen, hydrogen and sulfur.

How do we fingerprint nutrients from different sources?

Nitrogen and phosphorous are the two main nutrients essential for plant growth. Nitrogen dissolved in lakes and rivers most often occurs as nitrate (NO₃)_. In nitrate, the amount of the rare stable isotope of nitrogen (¹⁵N) can vary depending on whether it is sourced from natural processes, artificial fertilizers, or animal and human waste. The amount of ¹⁸O (a stable isotope of oxygen) in nitrate can be different too. We can measure these differences and use them to determine where the nitrogen in excess nutrients are from.

Determining the sources of nutrients is an important first step to managing the amounts of nutrients to Lake Winnipeg. Once we know where these excess nutrients are coming from, we can suggest best management practices to mitigate the amount of man-made nutrients released into the environment.

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Why are cyanobacteria important?

Cyanobacteria blooms are important to study and monitor, because they can produce toxins and other molecules that are dangerous for the public, and for animals.

Examples of Canadian lakes highly affected by cyanobacteria blooms are southern parts of Lake of the Woods (Ontario, Manitoba), western Lake Erie (Ontario), and Lake Winnipeg (Manitoba). They are currently studied through the Canada-U.S. Lake of the Woods program, the Great Lakes Protection Initiative and the Lake Winnipeg Basin Initiative.

How to determine if a bloom is toxic?

Scientists studying cyanobacterial and harmful algal blooms or HABs are responsible for the identification of those toxins and other molecules. Some toxins are easy to identify, as they have been studied for decades around the world. An example would be the toxin microcystin-LR, responsible for the death of various animals, including dogs. However, scientists are searching for new molecules – toxins – that have not been monitored yet and could have a strong impact on the environment.

Detecting and identifying those toxins starts by filtering lake water using various processes to be able to extract the toxins from the algae and cyanobacteria. The extract is then analyzed using liquid chromatography and a mass spectrometer.

In simple terms, this instrument first separates the different kind of toxins by their chemical and physical properties in the liquid. Once this is done, the mass spectrometer give us a pattern of signals called spectra. The spectra is unique for every single compound, and this is how we can tell what toxins are present in the water.

What’s next?

By increasing our knowledge on the abundance of toxins, their production, and their distribution in Canadian lakes, the Harmful Algal Blooms scientists are hoping to be able to predict the toxicity of future blooms and avoid sickness for the population, the wildlife, and our beloved pets.

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Research scientists at Environment and Climate Change Canada are actively involved in collaborative work with toxigenic cyanobacterial and harmful algal blooms (cHABs) and source-water impairment in systems across Canada including in the Lake of the Woods, Lake Winnipeg, Lake Erie, and Lake Ontario. Scientists are examining the factors regulating the abundance, diversity, and function of microbes, their chemical ecology, and the fate and consequences of natural toxins produced in these systems. This is accomplished with the help of tools to measure the biological components of cHABS and to reconstruct past climatic and environmental conditions. Also, large-scale field studies and surveys are conducted to collect samples and data.

One such project entitled, “Cyanobacteria in Lake of the Woods: origins of blooms, sources of toxins, and drivers” aims to improve understanding of nutrient dynamics and cHAB occurrences on Lake of the Woods. The focus will be on researching sources, causes, transport, composition, and toxicity of cHABs and improve monitoring throughout Lake of the Woods. Results will document the status, trends, and drivers of blooms, and the risk they may pose, to inform on appropriate management and mitigation strategies.

This project integrates detailed lake-wide spatial surveys, advanced analytical and molecular methods, and satellite earth observation imagery. Sampling is being conducted across seasons to identify variability of phytoplankton biomass, classification, pigments, toxicity, and optical properties, along with a suite of core water quality parameters, nutrients and wastewater tracers.

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What are mathematical models?

Mathematical models are virtual representations of real-world systems to help complement direct measurements in the study of complex processes. Computers can help with mathematical modelling of environmental problems. Computer modelling is used across many disciplines, including atmospheric sciences. Have you ever wondered how you get weather forecasts in your phone? This is a vast topic commonly known as Numerical Modelling. Easier access to supercomputers is allowing scientists to explore these computer techniques like never before.

How does modelling help water science?

In water sciences, scientists have long realized that the relationship between hydrological, hydraulic, biogeochemical, ecological, social and economic processes are often far too difficult to understand without the support of models.

Being able to understand these processes is essential. It allows us to answer important "what," "why," and "when" questions. These answers will help our society to both understand our world a bit better and provide useful knowledge that help to improve people's lives.

In the science of water, scientists work every day in Canada and around the globe to improve existing models to address both new and old problems. One major problem scientists are considering is the effect of climate change on water availability and quality. Models can also help in determining actions that can help to improve water security.

What are some challenges of water science modelling in Canada?

In Canada, it is challenging to understand and predict how water moves through farm fields, forests, grasslands, lakes and river basins. This knowledge is critical to understanding water quality as well. Our cold climate means that water can co-exist as water vapour, liquid water and snow/ice. This affects how water moves in the environment. When soil freezes, the amount of water that can infiltrate is reduced which increases the risk of flooding. Rain in the winter can fall on snow, causing flashy and massive floods. Blowing snow can cause large amounts of snow to move across the landscape. This affects how much snow accumulates and where. Permafrost (ground that has historically remained completely frozen for at least two consecutive years) is melting and changing Arctic lakes, ponds and streams.

It remains challenging to develop accurate computer predictions especially in cold regions such as Canada. Some of the research we do will help improve our modelling and monitoring capabilities.

Watershed Hydrology and Ecology Research scientists are focusing on three main approaches to help explore new and emergent technologies:

1. Mathematical Modelling with computers:

   • developing a variety of new tools to investigate contaminant dynamics in rivers
   • simulating nutrient release and movement during snowmelt from agriculture fields in temperate and cold regions
   • simulating dissolved ions during pulses of snowmelt

2. Field and Laboratory experiments:

   Performing laboratory/field-based studies to develop new and better computer models. These will help to formulate hypothesis and improve our scientific understanding of hydrological and biogeochemical processes.

3. Monitoring systems and sensors:

   Collaborating with the University of Saskatchewan to develop a new Nutrient App. This mobile application supports farmers, citizens, communities and water quality managers to reduce nutrient pollution in rivers and lakes by sampling nutrient concentrations (phosphate and nitrate-nitrogen found in fertilizer). The app is available for Android (Google Play) and iOS (App Store).

Learn more about our Environment and Climate Change research.

When it comes to the wastewater, we generate each day, most people “flush it and forget it”. The water that goes down our drains and flushed down our toilets is treated before being released back in to the environment. In cities, the sewer system collects wastewater, then carries it to wastewater treatment plants to undergo various treatment methods. The effluent (treated water) is then released back into the environment into a nearby stream or lake. 

In rural areas, wastewater is treated by a septic system that consists of a tank where treatment begins and a tile drain system where effluent is discharged to the ground for further treatment. Eventually, treated septic effluent makes its way to the shallow groundwater system.

How do scientists trace wastewater in the environment?

Most of the wastewater treatment facilities, whether municipal or septic systems, were not designed to effectively remove many of the chemicals we now use in our daily lives. As a result, some of the chemicals that go down our household drains and toilets can survive wastewater treatment processes and end up discharged into the environment in the wastewater effluent. These “persistent” chemicals include some pharmaceutical drugs such as pain medications, antibiotics, antidepressants, and other chemicals such as caffeine and artificial sweeteners.

Environment and Climate Change Canada scientists analyzed four artificial sweeteners – acesulfame, saccharin, cyclamate, and sucralose – to detect wastewater in lakes, rivers, and groundwater. Artificial sweeteners provide their sweetening effect to food without providing calories because the body cannot digest them so they pass through the body unchanged. Artificial sweeteners are found in sugar-free gum and soft drinks, cough syrups, and even toothpaste!

Scientists examined artificial sweetener concentrations in the Grand River in Southern Ontario. Twenty-three sites along the length of the Grand River were sampled and analyzed for the four artificial sweeteners. Given that there are 30 wastewater treatment plants discharging effluent into the river, scientists were not surprised to find the four artificial sweeteners in the water. At the time, the concentrations measured for saccharin, cyclamate, and sucralose, were the highest found in any river or lake in the world! This study confirmed that artificial sweeteners are a good tool to use to detect wastewater in the environment.

Learn more about:

• Artificial sweeteners in our environment
• Environment and Climate Change Canada Scientists

When excess nutrients, such as phosphorus, end up in lakes they act as a fertilizer for naturally-occurring algae to (over)grow. It is challenging to determine where lakes get their nutrients because there can be many different sources. One potential source is septic effluent (wastewater), which is normally enriched in such nutrients, and after it infiltrates the ground becomes groundwater. Scientists at Environment and Climate Change Canada conducted research to assess whether developments along the shorelines of lakes in the Canadian Shield cause nutrients such as phosphorus, to enter the lake as groundwater seepage, potentially leading to harmful algal blooms.

On eleven trips to Lake of the Woods in northwestern Ontario between 2016 and 2019, we collected samples of septic wastewater, groundwater and surface water and analyzed their nutrient concentrations and various other indicators of water quality. This included phosphorus and other nutrients as well as substances that act as tracers of wastewater. A novel method in this study was to analyze the artificial sweetener “acesulfame”, which is a good tracer of septic wastewater as it tends to stay dissolved in water, it does not break down easily, and it is present at levels that are easy to measure. A comparison of the amounts of phosphorus and acesulfame in the different samples shows that much of the phosphorus in the septic wastewater is removed as this water percolates through the ground, so that only a small portion of the phosphorus remains in the groundwater that flows toward the lake.

We sampled lake water in Poplar Bay in the north part of Lake of the Woods. This bay has many cottages along its shoreline. The bay is connected to the rest of the lake by a narrow channel. We found that the concentrations of acesulfame in Poplar Bay were high when compared to other places in Lake of the Woods. This acesulfame was in the septic wastewater from the cottages that percolated into the ground along the shores of the bay and it was then carried by the groundwater that seeped from these shores into the bay. In contrast, we found that the water in Poplar Bay tended to have lower phosphorus levels compared to the other Lake of the Woods samples. This is not surprising when we take into consideration that, as noted above, unlike the acesulfame, most of the phosphorus in the septic wastewater was removed as it percolated into the ground near these cottages.

In the bigger picture, we found that the concentrations of phosphorus in pristine (uncontaminated) groundwater sampled along the shores of Poplar Bay and along other shorelines of Lake of the Woods tended to be about ten times higher than in the lake. This suggests that natural seepage of pristine groundwater along the shorelines may be an important source phosphorus in the lake. It remains unknown whether this natural groundwater source of phosphorus can enhance the growth of algal blooms along the shorelines of Lake of the Woods. Detailed information is missing about the rate of the seepage of groundwater to the lake, and it will be challenging to get this information.

In summary, using a sweetener as a novel tracer, we found that the phosphorus from cottage septic wastewater is largely removed as it percolates into the ground. The results of this study may be relevant to many other lakes on the Canadian Shield that have undergone similar developments.

• Research at Environment and Climate Change

Why do scientists study river ice?

While there have been many scientific advancements in the study of both climate change and river ice over the past four decades, little is known about the current state and future predictions of river ice across Canada. Each year, river ice formation, growth, decay and clearance can include low flows and ice jams, as well as midwinter and spring break-up events. WHERD scientists recently produced the Canadian River Ice Database (CRID), which includes observations of water level, flow and timing as rivers change from a liquid to a solid state every year. Some of these records span more than 100 years! Just like an ice cube melting on a hot day, we know that temperature and the surrounding climate is the main reason why river ice forms and melts each year. At any time from September to June, river ice is either forming, growing or melting in Canada. River ice scientists study the freeze-up, midwinter and break-up periods since large buildups of floating ice chunks can temporarily dam up rivers and cause floods.

Why is river ice important?

While it can be complicated to understand where, why and when river ice happens in Canada, the CRID along with Environment and Climate Change historical climate data including temperature and weather (for example, rain, snow, solar radiation, clouds) can be used to understand how climate change impacts river ice. We use the things we learn so we can better inform Canadians where damaging river ice and flooding can occur. While river ice can be dangerous, it is also a very important part of the hydrological cycle and the environment. Many regions in Canada rely on annual flooding to replenish lakes and wetlands, while during the winter fish habitats are protected under the cover of ice. To learn more about how ice jams are important to fish and riverside ecosystems please visit: Arctic delta pond ecosystems, seasonal flooding and adaptation.

For many northern communities Canada’s frozen rivers are important transportation routes during the winter months, simplifying the movement of people and supplies across much of Canada’s landscape.

Identification of climate induced trends in river ice thickness, ice-cover duration along with the freeze-up and break-up periods is very important for understanding the impacts on riverside communities. A preliminary map using CRID data indicates the ice cover season on many rivers in Canada is getting shorter, though some nearby locations show opposite trends.

Next time you see river ice or hear a story about an ice jam remember that nearly all of Canada’s waterways are frozen at one time or another during the year.

Related links

• Canadian River Ice Database – Open data
• Canadian River Ice Database – National Hydrometric Program Archives
• Ice jam formations (The Globe and Mail article)
• Research at Environment and Climate Change

What is groundwater?

Groundwater is water found beneath your feet in the ground. It’s found between sand and gravel particles and in the cracks and crevices in bedrock. Groundwater accounts for about 30% of all the freshwater in the world; 100 times more than the water found in the all the world’s lakes, rivers and wetlands combined. In addition to groundwater’s importance as a drinking water source for many Canadians, groundwater also sustains water levels in many rivers and wetlands, particularly in winter months and during periods of low precipitation.

Climate change is expected to impact how and when groundwater contributes to rivers and the groundwater-dependent habitats they support, but the consequences of these changes are not fully understood. Presently, WHERD scientists are studying the impact of climate change on groundwater and its effects on rivers and aquatic habitats in northern regions of Canada.

How is climate change impacting groundwater in the North?

Groundwater is very important for supplying water, minerals and temperature regulation in many rivers, lakes and wetlands, particularly during winter and times of dry weather. Warming temperatures and changes in precipitation patterns associated with climate change will alter groundwater’s influence in northern environments. The thawing of permafrost (permanently frozen ground) and longer ice-free periods in seasonally frozen ground resulting from warming temperatures will alter the groundwater flow to rivers, lakes and wetlands. Changing groundwater discharge will not only affect water flows, but will also impact the quality of water in rivers, lakes and wetlands. With northern Canada warming more than twice as fast as the global average, there is concern about how changes in groundwater could negatively affect the plants and animals that live in groundwater-dependent ecosystems.

Why is groundwater important for salmon?

Groundwater is particularly important for many salmon species in Canada. Salmon lay their eggs in locations where groundwater discharges to rivers and some lakes. In northern Canada, groundwater provides enough heat during the winter months to keep the salmon spawning beds from freezing and supplies the buried eggs with the energy needed to develop.

How are scientists learning about climate change impacts on groundwater and salmon?

WHERD groundwater scientists are working with scientists and staff from the Yukon Government, Kluane First Nation, Champagne and Aishihik First Nations, Parks Canada and the Department of Fisheries and Oceans to better understand the impacts of climate change on groundwater and the effects on vital spawning habitat for chum and kokanee salmon.

1. In 2017, scientists from Environment and Climate Change Canada began studying how and where climate-induced changes in groundwater may affect salmon species in Canada’s north. Within the traditional territory of Kluane First Nation, water levels and flows in Lhù’ààn Mânʼ (Kluane Lake) and Lhù’ààn Tǎgà’ (Kluane River) have been affected in recent years from the dramatic decline in the meltwater flowing from the Kaskawulsh Glacier towards the lake. The decline in Kluane Lake’s water level has exposed formerly submerged salmon spawning areas. In addition to the lake changes, the study explores if climate change and permafrost melting are affecting the discharge of groundwater to Lhù’ààn Mânʼ (Kluane Lake) and what are the impacts to the available spawning habitat for chum salmon. This study combines traditional knowledge from Kluane First Nation People and Western science.
2. The land-locked population of kokanee salmon in the Kathleen Lake watershed in Kluane National Park and Reserve, and in the traditional territory of Champagne and Aishihik First Nations, experienced a dramatic drop in numbers about two decades ago. The cause of this population crash is unknown. During water sampling of creeks near the kokanee spawning beds in 2018, scientists detected unusually high concentrations of various metals that are known to be harmful to fish. Scientists began examining stream flow and chemistry in the area to investigate the possibility that climate change effects were responsible for the low kokanee spawning counts. In particular, the study is investigating if earlier and more intense summer “heat waves” are resulting in the release of naturally occurring, but toxic, metals from the frozen ground into the groundwater and streams and if these metals play a role in the crash of the kokanee population.

Climate change and the hydrologic cycle in Canada

What is the hydrologic cycle?

It is the movement of water, driven by the heat of the sun, from the surface of the Earth to the atmosphere and back to the Earth in a continuous cycle.

How does climate change effect the hydrologic cycle?

Global warming has caused noticeable changes in climate and the various hydrological processes. The current science suggests that climate change is intensifying the hydrologic cycle, particularly at high latitude countries like Canada. Scientific evidence also indicates that climate change is varying over time, meaning there will be an increase in the frequency and magnitude of extreme weather events, including flooding and droughts.

Precipitation and temperature are the two most important climate variables that determine water resources potential in a region. The slightest changes in the magnitude and/or spatial and seasonal patterns of these variables can affect water availability through shifts in water/snow storage, evapotranspiration and runoff. While warming has been observed consistently across most of Canada, stronger trends are found in the north and west. Changes in precipitation have also varied by region and season, with the largest percentage increase in precipitation being in the high Arctic, while parts of southern Canada (particularly the Prairies) have seen little change or even a decrease. In cold regions like Canada, a warmer world would lead to less winter precipitation falling as snow and the melting of winter snow occurs earlier in spring. Even without any changes in precipitation intensity, both of these effects lead to a shift in the timing and magnitude of high and low flows with peak flows advancing to early spring, away from summer and autumn when demand is highest.

How do scientists study the impact of climate change on the hydrologic cycle?

Scientists are currently investigating the potential impacts of a changing climate on regional water availability, watershed hydrology and hydrologic extremes and the impacts on aquatic ecosystems. They do this with the help of hydrologic, climate and land management models. For example, data from Global Climate Models (GCMs) were used to compute the standardized precipitation and evapotranspiration index (SPEI) which helps to predict near and far future water availability at western and southern Canadian river basins (Figure 1).

To predict the long-term hydrologic impact of climate change in the Athabasca watershed, ECCC scientists applied the Variable Infiltration Capacity (VIC) hydrologic model. This model predicts the increase in spring and winter flows in the Athabasca River towards the end of this century that would result in decreasing summer flows because of earlier snowmelt, increased evapotranspiration and no projected increase in summer precipitation. The potential impacts on the hydrodynamic and sediment transport regime of the lower Athabasca River (Figure 2) was also investigated and results suggest an overall increase in mean annual sediment load in the river.

Lake Winnipeg, Manitoba, has been experiencing frequent algal blooms due to high nutrient levels from multiple sources. Many Lake Winnipeg watersheds are dominated by agricultural land use where nutrient-rich runoff, flowing into this shallow lake, has major impact on its water quality. Nutrient export from the watersheds depends on hydrological conditions, variability in the hydro-climatic regime and land management practices. ECCC scientists will be implementing an improved version of the Soil and Water Assessment Tool (SWAT) to investigate the potential impacts of projected climate change and various beneficial management practices (BMPs) scenarios on the hydrology and nutrient transport regime.

• Research at Environment and Climate Change