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Water Today Title July 7, 2022

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Asvisory of the Day



This story is brought to you in part by Nature's Pond

Early last week, staff from Lower Thames Valley Conservation Authority (LTVCA) observed a "discolouration" in the Thames River. This prompted the group to contact the Ontario Ministry of Environment and Climate Change (MOECC) whose staff conducted sample testing. In a release on August 30, LTVCA stated that the MOECC test results indicated that the discolouration "was a cyanobacteria (blue-green algae) bloom," and that it was the same species that caused problems for drinking water intakes on Lake Erie.

We spoke with Austin Pratt, LTVCA Water Quality Specialist, to get a better sense of the situation.

Pratt said that "water levels in the Thames river through Chatham are controlled by the water levels in Lake St. Clair, so even though there has been minimal rainfall the past few weeks, there is still a significant depth of water." The problem is that it is virtually stagnant. Pratt explained, "the water is just sitting there because there is no push from higher flows upstream." He added, "this combined with warm weather, resulted in favourable conditions for the growth of blue-green algae."

Last month we saw that in Chatham-Kent there are still quite a few agricultural lands, perhaps farming or another local activity may have had an affect on the bloom? Pratt said that "excess nutrients including Phosphorus are a chronic issue within the Thames watershed." The river itself "has been targeted in the Draft Domestic Action Plan,[...] to reduce the frequency of [algal] blooms." Aside from that Pratt confirmed that "no local activities or discharge events have been identified, which could have triggered this particular bloom."

The bloom is "confined to a beach in the immediate vicinity of Chatham, and is distributed throughout the water column, however, there is no apparent concentration on the surface." Since the initial observation, the intensity of the colour has lessened and Pratt attributes this to "stronger winds and cooler temperatures." However, the lab analysis "confirmed the presence of Cyanobacteria as Oscillatoria and Microcystis species." No notice of a toxin analysis has been given and no impacts on wildlife have been reported.

We approached Pratt on what LTVCA would like to see done about the situation and he had this to say. "This blue-green algae bloom wasn't triggered by a particular event, which reinforces that this is a watershed-wide issue that needs to be dealt with." This begins with phosphorus reductions, Pratt is realistic reductions "to the target levels will require the implementation of multiple best management practices over much of the landscape, paying particular attention to reducing wet weather loadings most often associated with the timeframe outside of the growing season."

The situation on the Thames River watershed is such that there needs to be a reduction is phosphorus. To achieve this on the scale described by Pratt will take "significant resources including funding to meet targets," there has to be enough staff to make the required interventions. In the meantime, the MOECC and LTVCA will continue to monitor the situation.

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