Agricultural Run-Off A Main Focus of Great Lakes' Eutrophication Concerns


Environmental Defence and Freshwater Future Canada released a four-point action plan this week entitled Clean, Not Green: Tackling Algal Blooms in the Great Lakes. The plan comes in the wake of recent, serious algal blooms in the Great Lakes (specifically Lake Erie) and looks to improve agricultural practices, city planning, education and policy around maintaing clean water systems.

“The Great Lakes supply drinking water for millions of people, and are critical to Ontario’s fishing, boating and tourism industries,” said Nancy Goucher, Water Program Manager with Environmental Defence. “Allowing them to be covered in green slime every summer is simply not an option.”

Related: Conservation Agriculture on the Shores of the Great Lakes

Healthy riparian zones can slow and filter surface water, decrease erosion.
Healthy riparian zones can slow water, and decrease nutrient erosion.

Water quality issues in the Great Lakes emerged in the 1960s, according to Environment Canada, but collaborative efforts between the United States and Canada enabled vast improvements over the course of the next twenty years. In the mid-1990s, however, the problems re-emerged continue to this day, with phosphorous being the primary concerning factor.

Today, climate change and invasive species have changed the ecosystem, and recurring blooms suggest that current land-use practices are not sustainable in the Lake Erie watershed and more broadly across the Great Lakes basin.
From Clean, Not Green: Tackling Algal Blooms in the Great Lakes Executive Summary

Excess phosphorous in water bodies often gives rise to algal blooms, and in some instances, can lead to the presence of mycotoxins created by certain blue-green algae species. Additionally, once the phosphorous is depleted, or some other change no longer promotes the growth of algae, the blooms die and sink to the bottom, where their decomposition uses the oxygen, creating “dead zones” or areas where plants and fish can no longer survive.

The Solutions

The four-point plan deals first with agricultural runoff. This is certainly not surprising. News coverage thus far suggests that unlike the link between sewage treatment and algal growth in the 1960s, more recent blooms can be attributed to intensive agriculture. In fact, a report by the Lake Erie Ecosystem Priority, published in February, identified runoff as one of the key contributors to excess nutrient loads in Lake Erie. In 2011, the lake saw one of its worst algal blooms to date, and according to the publication, an estimated half of the phosphorous load came from monitored tributaries of Lake Erie, including those from rural and agricultural lands.

Related: 3 Guiding Principles of Conservation Agriculture for a Large-Scale Operation

Tips for Reducing Runoff:
1. Maintain healthy riparian zones
2. Reduce summerfallowing
3. Do not apply fertilizer to saturated,
frozen, snow-covered, or heavily
compacted bare soils.
4. Prevent livestock from entering
5. Strategic drainage to slow water movement
6. Use zero- or minimum-tillage
7. Avoid fall tillage
8. Consider using cover crops in rotation
The first point of the four-point plan is thus to harness market forces in order to help farmers reduce nutrient runoff. This is hoped to be done through further education on the proper application of nutrients and an evaluation of market mechanisms that will create incentives to reduce nutrient runoff (e.g. tax-shifting, pollution taxes, nutrient trading).

“Our plan is about giving farmers the tools and financial resources they need to help reduce their nutrient runoff in the lake,” said Environmental Defence’s Goucher. “Reducing the amount of phosphorus in the lake will have a huge impact on the size and frequency of algal blooms in the future.”

The plan also identifies the importance of water smart cities and citizens, improving understanding of algal blooms, the investment in green infrasturcture, expansion of septic system maintenance and upgrades to sewer systems subject to overflows. In terms of policy, the report suggests the first step towards the binational Great Lakes Water Quality Agreement is to finalize the Canada-Ontario Agreement and for Ontario to pass the proposed Great Lakes Protection Act.

Featured Image CreditF. Lamiot, Creative Commons.

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