Algal Blooms 101 – Part 2

By David Ernes – Lake Management Committee

This is the second in a series. This is not meant to be a comprehensive overview, but is intended to give the reader some basic information on this important lake management subject.

Algal blooms obviously have an aesthetic concern – they just don’t look nice. But the recent news regarding the Toledo bloom brings up another issue – toxins (aka cyanotoxins). These toxins are not associated with common green algae but with cyanobacteria (blue-green algae). Cyanobacteria blooms, as a result, are often called “Hazardous Algal Blooms” or HABs. The good thing is that not all cyanobacteria produce toxins. However, some species of cyanobacteria can produce more than one type of toxin. Obviously, this issue is complex. In spite of all of this attention, the US EPA has not yet set advisory thresholds above which exposure to these toxins should be avoided. The advisory thresholds that you see in the news and elsewhere are either the early World Health Organization (WHO) values, or those set down by the OhioEPA. Most, but not all states have cyanobacteria or cyanotoxin thresholds for exposure, and they differ from state to state. The thresholds for recreational exposure (like for our lake) are typically less severe than those for drinking water (like the Toledo issue).

Exposure to toxins can result in everything from a mild rash to a more serious condition depending on the toxin concentration and exposure. Since it is not possible to tell visually if a bloom is due to cyanobacteria, or if the cyanobacteria have released any toxins, it is best to avoid contact with an active bloom. The tag line on the OhioEPA site is “When in doubt, stay out”.

The only way to determine if toxins exist is to test. Reliable test results require careful sampling and analysis in a qualified lab, both of which are expensive. On the RRA web site, the toxin level results from our two beaches are published. The values for our lake continue to be below recreational advisory thresholds. If the level were to exceed these recommendations, signs will be posted at the two beaches to warn of the advisory. With hard work, good lake management, and the help from our neighbors, we hope to never have to use those signs.

The OhioEPA website (one of the sources of the information in this article) has a lot more information on this topic.

BE LAKE RESPONSIBLE