Greenhouse Canada

Managing greenhouse retention ponds

November 13, 2018  By Agricultural Adaptation Council (edited)

Retention ponds play an important role in helping Ontario greenhouse growers manage storm water. It’s not clear, however, how they influence water quality as the water flows from roof to pond and ultimately to surrounding watersheds and Lake Erie.

Ontario Greenhouse Vegetable Growers (OGVG) have launched a project, supported by the Canadian Agricultural Partnership, with researchers from the Great Lakes Institute for Environmental Research (GLIER) at University of Windsor to close some of the knowledge gaps around these ponds.

“One of the things we want to learn is whether these ponds enhance nutrient retention or contribute to nutrient load in surrounding watersheds – and whether sediment in the ponds serve as nutrient sources or sinks,” says Nathan Warkentin, OGVG energy & environment analyst.


Through sampling and analysis of water from different retention pond types and sizes at four different sites, a phosphorus assessment will be developed focusing on Leamington tributaries like Sturgeon Creek. The area is home to the majority of Ontario’s greenhouse vegetable producers.

“We’ve gotten very good in our lab at diagnostically looking at shifts in microbial systems in healthy versus stressed environments,” explains GLIER’s Dr. Christopher Weisener. “Coupled with our work on stable isotopes, it lets us look very specifically at what types of cycles and chemical transformations are happening – and compare the impact of current pond systems with those used 15 or 20 years ago.”

By the end of the two year project, the goal is to be able to develop realistic and applicable management recommendations for greenhouse growers that will help reduce phosphorus pressures on Lake Erie.

Currently, blanket recommendations exist, but development of strategies for the different pond types will be very valuable for the sector, according to Warkentin; not only will it help growers improve their environmental performance, but there could be economic benefits too.

“We are fortunate to find this avenue of funding to support engagement between growers and academia and have partnerships like this to address challenges in the sector,” adds Dr. Scott Mundle of GLIER.

The project is eligible to receive just over $140,000 in cost-share funding through the Canadian Agricultural Partnership.

This project was funded in part through the Canadian Agricultural Partnership (the Partnership), a federal-provincial-territorial initiative. The Agricultural Adaptation Council assists in the delivery of the Partnership in Ontario.

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