DETECTING TOXIC HABS IN THE USA AND CANADA

Inconsistent regulatory standards between the two countries

A surprising test result came up for Lake Erie, a relatively moderate concentration HAB has produced total microcystins levels five times above the EPA 2019 safe limit for recreational water, just weeks after this HAB first appeared in Lake Erie. The beach was been posted with an algal toxin warning over the weekend. Maumee Bay State Park in Lucas County Ohio has a sheltered bay area at the east end where the wind drives mats of cyanbacteria against the shore, at times piling up a thick scum mat that can reach a very high concentration. As observed last year, the scum mat that formed throughout the month of July brewed away at 2 to 3 million cells per 100 ml for three weeks before water testing prompted a beach advisory, the total microcystins found at 85 times the safe limit for recreational water on August 4th, 2023. The widespread HAB observed this season in Maumee Bay State Park has not been observed over 500 thousand cells per 100 ml, and has not been around quite as long as last year's HAB.

This toxin result prompts us to look around to other water bodies and other jurisdictions.  The satellite HAB monitoring program offers eyes on a dozen high profile water bodies in the USA, three of which fall inside the WT coverage area in NY, Ohio and Louisiana.  Unfortunately we do not have the benefit of observing HABs everywhere, relying on state or local public reports as available.



What then of the HABs situation in Canada?  The established parameters for HAB toxin microcystins in recreational water north of the border are two and a half times higher than what is considered safe in the USA.  Considering the more liberal threshold for HAB toxicity in Canadian waters, the recent Lake Erie test results are still over that safe limit, in fact, double.  How do the health authorities in Canada ensure the safety of public drinking water and recreational water?  The western province of Alberta has implemented a satellite observation program for selected water bodies, combined with real time water testing.  The images are collected by a Sentinel II satellite snapping the images every eight days; the information is available to the authorities, not available to the public.  Media outlets are running HAB stories every day, visual observations are reported, the advisory signage is posted to warn the public.  What are the toxin levels measured in these lakes?  Is the public fully informed of the risks?  While the level of microcystins is not published, alerts are issued when the algae are revealed to contain toxins. The level of reporting is uneven across Canada, with some provinces not reporting blue-green alerts specifically (Saskatchewan, Newfoundland, Quebec) and others tracking them faithfully (Ontario, Alberta)

In Guidelines for safe recreational water environments published by the World Health Organization, Geneva 2003 includes a chapter on freshwater cyanobacterial and their associated toxins and threat to public safety, referencing known public health implications from studies published around the world. Here are some of the reasons we concern ourselves with HABs and public safety around recreational water, these factors being all the more compelling concerning drinking water sources:

• liver injury results in externally noticeable symptoms only when it is severe
• acute dose–response curves for microcystins are steep, meaning little acute damage may occur until levels close to severe acute toxicity are reached.