Eutrophication

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AC Atienza, Brendan Bate, Shannon Smithwick, Steff Stephansson, Kaleigh Watson, Andrew Wilson.

Sketch of urban and rural sources of nitrogen and phosphorus leading to eutrophication.
Nutrient enrichment pathways via river runoff, storm water runoff (Urban and Residential Runoff) and atmospheric precipitation; and effects of anthropogenic nutrient enrichment on phytoplankton biomass (Algal Bloom) and consequences of eutrophication, e.g., oxygen depletion of bottom waters (O2#) (Source: Hans Paerl, University of North Carolina). Source: http://dx.doi.org/10.3389/fmars.2020.00670.

What is “eutrophication”?

Eutrophication is the increase in the concentration of nutrients, primarily nitrogen and phosphorus, in a water body [1].  These nutrients can trigger events in the water body such as excessive growth of organisms such as algae in events called “algal blooms”.   These blooms can produce toxins that are harmful to aquatic life and humans, reduce underwater light levels which reduces photosynthesis and creates dead zones where oxygen levels are too low to support aquatic life.   In sum, these various effects can collapse the local ecosystem [2].

Beyond the effect on the aquatic ecosystem, eutrophication can threaten human health by contaminating drinking water supplies [3] and requiring more expensive treatments to make the water drinkable.

Eutrophication is a growing global problem.   A 2009 report [4] for the World Resources Institute noted that in 1960, 10 coastal dead zones had been documented.   By  2008, the number of coastal dead zones was 405.   Climate change is expected to make the eutrophication problem worse [5].

What causes it?

Eutrophication can arise naturally over time.   However, more typically, it is the result of a sudden increase in nutrients resulting from human activities such as poor sewage management, industrialised forestry [6], urban run-off or agricultural run-off.   Agricultural run-off is typically in the form of chemically manufactured fertiliser or untreated sewage.   This results in water bodies receiving more nutrients than they can normally process.   Natural eutrophication is a slow and gradual process, but human activities can accelerate it and this results in the explosive growth of algae [7].

Agriculture

Poor water use practices, including inefficient irrigation and over-extraction of water, can worsen eutrophication.   Agriculture, which accounts for about 70% of global freshwater use [8], plays a significant role.   In Africa and Asia, it is estimated that agriculture accounts for 85-90% of freshwater use [9].  In stark contrast, Canada’s agricultural water use is around 11% [10].

Inefficient irrigation methods result in runoff, which carries fertilizers and pesticides into nearby water bodies [11].   Over-extraction of water for agricultural, industrial, and domestic use lowers water levels, concentrating nutrients and pollutants, making water bodies more susceptible to eutrophication.

Urban communities

Urbanization often contributes to poor water practices.   Impermeable surfaces such as roads, sidewalks and parking lots in urban areas increase runoff, which carries nutrients (and pollutants) from urban landscapes into water bodies.   The lack of adequate sewage treatment facilities in many communities means that untreated or partially treated wastewater is often discharged into rivers and lakes, further enriching them with nutrients.

Community practices also significantly impact the health of water bodies.   The use of human-made fertilizers and pesticides in residential areas contributes to nutrient runoff.   Practices such as improper disposal of waste including manure and compost, and the lack of green infrastructure [12], such as rain gardens and permeable pavements, to absorb runoff exacerbate the problem.

Also, people living near water bodies often engage in activities that can directly contribute to eutrophication.   These include recreational boating and fishing, which can increase erosion and runoff, and waterfront development, which often leads to shoreline habitat destruction and increased pollution.

What can be done to reduce eutrophication?

Eutrophication is a complex issue with many possible causes, both natural and human-induced.   Consequently, dealing with it and managing its harmful effects requires action on many fronts.

Adopting sustainable agricultural practices

Sustainable agriculture practices, such as precision farming [13] or regenerative agriculture, can significantly reduce runoff by ensuring that fertilizers and water are used efficiently.   Precision farming is, essentially, the intense use of data about factors such as soil moisture, fertiliser uptake, soil fertility and so on to allow for optimised application of water, fertilisers, and other inputs only where, when and in the amount needed.   An example of this approach in practice in Canada is the “4R Nutrient Stewardship” program [14].

Cover cropping [15] and buffer zones , especially near riparian areas, can also prevent soil erosion and reduce nutrient runoff into waterways.   Agricultural runoff management requires a careful analysis of water and pollutant flows and may require the creation of treatments such as vegetation filter strips or constructed wetlands [16] (pp.79-83).

More-informed community practices

Communities can play a vital role by adopting green infrastructure solutions that reduce runoff and by promoting the appropriate use of organic fertilizers  (i.e. manure and compost ) and pesticides.   Enhancing wastewater treatment processes to remove nutrients before they are discharged into water bodies is crucial.   As is so often noted, prevention is better than cure.  

Enhancing wastewater treatment

Wastewater treatment facilities can often be installed or upgraded to enable the removal of nutrients from the waste stream before the water reaches water bodies [17].   For communities relying on septic systems, promoting regular maintenance to prevent leaks and overflows is vital in reducing nutrient seepage into the groundwater and nearby water bodies.   In Canada in 2017, it is estimated that 270 million cubic metres of untreated wastewater was released into the environment [18].   While a large volume, it should be noted that the untreated volume is only 4.4% of the total wastewater volume produced in Canada.

Implementing green infrastructure

Photograph of an urban bioswale or rain-garden - an example of a nature-based solution to urban stormwater management.
Bioswale. Source: Meristem Design.
The use of green infrastructure [19] such as rain gardens, bioswales, green roofs in residential and commercial areas absorbs rainwater runoff and helps to filter out nutrients before they enter waterways.   Similarly, the use of permeable pavements [20] enables water to infiltrate the ground, reducing runoff and filtering pollutants.   An important possible benefit of the infiltration is that it may help in recharging aquifers and retaining water for future use.

Social and educational campaigns

Communities play a crucial role in combating eutrophication in lakes and rivers. By adopting sustainable practices and fostering environmental stewardship, communities can significantly reduce the influx of nutrients into water bodies.   By implementing the following strategies, communities can significantly reduce the nutrient loads entering their lakes and rivers, thus mitigating eutrophication and its adverse effects.   Active community involvement, coupled with strong policies and sustainable practices, can lead to healthier water bodies and ecosystems.

Community education and engagement campaigns

By raising awareness of the issue, public awareness campaigns can educate community members about the causes, dangers and effects of eutrophication and how the community can contribute to its reduction.   Similarly, “citizen science” programs (e.g. Water Rangers [21], or Our Living Waters [22] – a partner charity) and the Trout Unlimited Canada Yellow Fish Road program [23] can engage community members in monitoring water quality in local lakes and rivers.   This can increase awareness and provide valuable data for managing eutrophication.

Policy and regulation

Communities can advocate for stronger regional, provincial, and national regulations on nutrient pollution, including limits on the use of fertilizers and pesticides in agriculture.   It may also be possible to create fiscal and economic incentives (e.g. taxes, subsidies) which incentivise nutrient reducing activities.

At a more local level, communities can implement bylaws which:

  • Modify zoning and land-use planning to protect waterways from excessive nutrient runoff and promote sustainable development.
  • Guide the use of fertilisers and pesticides within urban areas.

Restoration projects

Communities can support projects to restore wetlands and riparian buffer zones.   Landowners can work with organisations such as Ducks Unlimited, Cows & Fish and ALUS in restoring wetlands on their land.

Restored riparian buffers along waterways are critical in intercepting surface runoff and providing habitat and biodiversity.   Wetlands act as natural filters, trapping nutrients and sediments before they reach larger bodies of water (e.g. Vancouver’s constructed wetland on Lost Lagoon [24]).   And, very helpfully, such areas can help with flood mitigation [25].

Adopting sustainable landscaping and gardening practices

Communities can encourage the appropriate use of fertilisers through education campaigns focussed on proper amounts and timing of fertiliser use.   Promoting the use of native plants in landscaping will reduce the need for fertilisers as the plants are adapted to local conditions.  Such plants may also need less water and so reduce the risk of runoff.

Conclusion

Active community involvement, coupled with strong policies and sustainable practices, can lead to healthier water bodies and ecosystems.

By supporting and implementing the strategies identified above and others that may be more appropriate for your particular areas and issues, you can significantly contribute to the reduction of nutrient loads entering your lakes and rivers.  By doing so, you will be helping to mitigate eutrophication and its adverse effects.

Call to action

Become aware:

  • Do any of the water bodies in your area have eutrophication?
  • Do you know why it is happening?
  • Is anything being done to slow or stop it?
  • Seek out other resources on the issue such as H2Know.

Teaching ideas

Group activities

  1. Share or read stories or books that feature the concept of eutrophication and its effects on aquatic ecosystems, making it relatable and engaging.
  2. Show age-appropriate videos or animations that explain eutrophication and its consequences in an engaging and easy-to-understand way.
  3. Facilitate discussions about the sources of nutrient pollution, such as agricultural runoff and household waste, and encourage children to brainstorm ways to reduce it.

Science experiments

  1. Create small-scale models of a lake or pond using a container, water, and materials like sand and plants.   If time permits, add fertilizer to demonstrate how nutrient overload leads to algae growth and eutrophication.   Perhaps compare between models demonstrating different effects.   Simpler variation:  use jars of water and add varying amounts of fertilizer to observe algae growth over time.
  2. Start a garden project where children can learn about the importance of using fertilizers responsibly and the impact of excess nutrients on the environment.

Art & multimedia projects

  1. Explain what eutrophication is, using age-appropriate language and visual aids such as diagrams, illustrations or collages.
  2. Encourage children to create posters or drawings depicting healthy and eutrophic water bodies, helping them visualize the differences and understand the importance of preventing nutrient pollution.

Field Trips

Arrange visits to local water bodies or nature centres where eutrophication can be observed. Guides can explain the process and its impact on the ecosystem.

Sources

  1. Encyclopaedia Brittanica, 2024, Eutrophication.  https://www.britannica.com/science/eutrophication.  Accessed 2024-02-28.
  2. World Resources Institute, n.d., Eutrophication and Hypoxia.  https://www.wri.org/initiatives/eutrophication-and-hypoxia/learn.  Accessed 2024-02-29.
  3. Government of Ontario, 2022, Blue-green algae. https://www.ontario.ca/page/blue-green-algae.  Accessed 2024-02-28.
  4. Selman, M. and Greenhalgh, S., 2008, Eutrophication: Policies, Actions, and Strategies to Address Nutrient Pollution.  https://files.wri.org/d8/s3fs-public/pdf/eutrophication_policies_actions_and_strategies.pdf.  Accessed 2024-02-29.
  5. Sinha, E., Michalak, A.M. and Balaji, V., 2017, Eutrophication will increase during the 21st century as a result of precipitation changes.  https://www.science.org/doi/10.1126/science.aan2409.  Accessed 2024-02-29.
  6. Bonsdorf, E., 2021, Eutrophication: Early warning signals, ecosystem-level and societal responses, and ways forward.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7982367/.  Accessed 2024-02-29.
  7. Government of Ontario, 2022, Blue-green algae. https://www.ontario.ca/page/blue-green-algae.  Accessed 2024-02-28.
  8. World Bank, 2022, Water in Agriculture.  https://www.worldbank.org/en/topic/water-in-agriculture.  Accessed 2024-02-28.
  9. Government of Canada, 2020, Agriculture and water quality.  https://agriculture.canada.ca/en/environment/managing-water-sustainably/agriculture-and-water-quality.  Accessed 2024-02-28.
  10. Statistics Canada, 2024, Canadian System of Environmental–Economic Accounts: Water use, 2021.  https://www150.statcan.gc.ca/n1/daily-quotidien/240711/dq240711a-eng.htm.  Accessed 2024-09-19.
  11. Government of Canada, 2020, Agriculture and water quality.  https://agriculture.canada.ca/en/environment/managing-water-sustainably/agriculture-and-water-quality.  Accessed 2024-02-28.
  12. Green Infrastructure Ontario Coalition, n.d., Green Infrastructure: Overview.  https://greeninfrastructureontario.org/what-is-green-infrastructure/.  Accessed 2024-02-28.
  13. MacIntosh, M., n.d., Precision Farming: What is it?  https://canadianfoodfocus.org/on-the-farm/precision-farming-what-is-it/.  Accessed 2024-02-29.
  14. Fertilizer Canada, n.d., Stewardship.  https://fertilizercanada.ca/our-focus/stewardship/.  Accessed 2024-09-19.
  15. California State University Chico, n.d., Cover Cropping.  https://www.csuchico.edu/regenerativeagriculture/ra101-section/cover-crop-biomass.shtml.  Accessed 2024-02-29.
  16. Alberta Agriculture and Rural Development, 2010, Beneficial Management Practice: Environmental Manual for Livestock Producers in Alberta.  https://open.alberta.ca/publications/4851540.  Accessed 2024-02-29.
  17. Preisner, M., Neverova-Dziopak, E., and Kowalewski, Z., 2021, Mitigation of eutrophication caused by wastewater discharge: A simulation-based approach.  https://link.springer.com/article/10.1007/s13280-020-01346-4.  Accessed 2024-02-29.
  18. Statistics Canada, 2019, Municipal wastewater systems in Canada, 2013 to 2017.  https://www150.statcan.gc.ca/n1/daily-quotidien/190625/dq190625c-eng.htm.  Accessed 2024-06-25.
  19. Capital Regional District, n.d., Green Stormwater Infrastructure.  https://www.crd.bc.ca/education/stormwater-wastewater-septic/green-stormwater-infrastructure.  Accessed 2024-02-29.
  20. Capital Regional District, n.d., Permeable paving.  https://www.crd.bc.ca/education/stormwater-wastewater-septic/green-stormwater-infrastructure/permeable-paving.  Accessed 2024-06-25.
  21. Water Rangers.  https://www.waterrangers.ca/.  Accessed 2024-02-29.
  22. Our Living Waters.  https://www.ourlivingwaters.ca/. Accessed 2024-02-29.
  23. Trout Unlimited Canada, n.d., Yellow Fish Road.  https://tucanada.org/education-training/yellow-fish-road/.  Accessed 2024-06-25.
  24. Kerr Wood Leidal, n.d., Stanley Park Stormwater Treatment Wetland.  https://www.kwl.ca/project/stanley-park-stormwater-treatment-wetland/.  Accessed 2024-02-29.
  25. Opperman, J. and Galloway, G.E., 2022, Nature-based solutions for managing rising flood risk and delivering multiple benefits.  https://www.sciencedirect.com/science/article/pii/S2590332222002135.  Accessed 2024-02-29.

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Photograph of WaterPortal Board Member Ross Douglas

Ross Douglas

Board Member

Ross has extensive executive experience in Operations, Governance, Information Technology and Strategy at the board and senior management level including Mancal Corporation, Mancal Energy, Highridge Exploration and Atlantis Resources. He has worked in Oil and Gas, Coal, Commercial Real Estate, Portfolio Management, Recreation, Retail and Water and Wastewater Treatment. His experience is also geographically diverse having overseen operations in Canada, the United States, United Kingdom and Northern Ireland. Additionally, he has been on the board of companies with operations in Argentina, Azerbaijan, Barbados, Kazakhstan, and Russia. He has served on numerous Public, Private and Not for Profit Boards across a number of industries.

Ross has been active on several industry Boards and committees including the Canadian Association of Petroleum Producers (CAPP) and The Schulich School of Engineering Industry Advisory Council at the Schulich School of Engineering.

Photograph of WaterPortal Board Member Brian Mergelas

Brian Mergelas, PhD, ICD.D

Board Member

Brian is a seasoned Cleantech entrepreneur with a proven history of successfully bringing complex water technologies to the market.   With over 25 years of experience, he has led various organizations to achieve significant milestones in the industry. 

Having started as the founding CEO of the Pressure Pipe Inspection Company (PPIC) and later taking the helm at the Water Technology Acceleration Project (WaterTAP), Brian’s entrepreneurial spirit has been instrumental in driving innovation and growth within the sector. 

He is an active investor in the cleantech sector and has served on many boards including the Ontario Clean Water Agency. 

Actively engaged in industry associations like AWWA, WEF, IWA, and ASCE, Brian enjoys collaborating with fellow professionals to promote advancements in the field. 

Brian holds an undergraduate degree and a PhD in Physics from Queen’s University, which has provided him with a solid technical foundation.   As a member of the Institute of Corporate Directors, he brings valuable insights to corporate governance.