Water treatment workers better equipped to monitor harmful algal blooms after calibration event

Posted by: GLOS_Admin March 12, 2019

Feb. 26, 2019: Water managers and researchers from Lake Erie cities gathered to calibrate sensors used to detect harmful algal blooms (HABs). The event, held at University of Toledo’s Lake Erie Center, brought together individuals from The Ohio State University, University of Toledo, Bowling Green State University and municipal water treatment facilities from as far away as Poland, Ohio.

In preparation for the upcoming summer HAB season, these sensors, had to be adjusted to relay accurate data so that readings from one location could be compared to another. Blue cylindrical devices contain multiple of these sensors that measure chlorophyll, pH, dissolved oxygen and more– measurements that water managers use to detect algal blooms and determine how to treat the water.

Being able to detect algal blooms before they enter the water treatment system is critical to water managers and researchers, especially in the wake of the 2014 Toledo water crisis, when a toxin released by harmful algae made its way into the drinking water supply, causing a three-day “Do Not Drink” advisory.

The calibration process involved cleaning the sondes and setting baseline measurements. When sondes are properly calibrated, they can be effectively combined into a network that expands beyond one water intake and can be used to better understand and predict harmful algal blooms.

Live data from the sondes is visible on a website ( created by Great Lakes Observing System (GLOS), where sensor data is mapped and can be compared for reference by water managers or anyone with an internet access.

Ed Verhamme, of environmental engineering firm Limno Tech in Ann Arbor, Mich. was the primary organizer and maintains relationships with water managers throughout the area, serving as a point of contact as they adopt and maintain the technology.

The event came as part of a larger project led by GLOS in partnership with Limno Tech, Ohio Sea Grant, NOAA, and Cleveland Water Alliance to create an early warning system in Lake Erie. The system would take in data from various sensors and stations and integrate it with models data to generate water quality alerts. The aim is to quickly relay critical HAB information to decision makers so they can better anticipate and react to dangerous water quality situations.

The event was funded by the Great Lakes Observing System (GLOS), through a federal grant administered by the National Oceanic and Atmospheric Administration (NOAA).

A spring calibration event will take place in May. Those interested can contact

Sonde sensors can detect algae in the water