In May 2013, the Ohio EPA released a Harmful Algal Bloom Response Strategy targeted at Public Water Systems (PWSs). This new publication shares several discoveries made between 2012 and 2013 that are relevant to PWSs for the detection and treatment of Harmful Algal Blooms (HAB) in Ohio.
At the end of 2012, the Ohio EPA reported that cyanotoxins, toxins produced by the cyanobacteria found in HABs, were detected in the source waters for thirteen public water supplies, but there were no finished water detections (2012 Public Water System Harmful Algal Bloom Summary, 2012). This good news of no detections in finished water was followed by the report of several challenges that will affect PWSs in the coming years.
The effect of HABs on raw drinking waters is increasing in HAB-affected source waters. The Ohio EPA reported that the average microcystin concentrations (liver toxin produced by a number of cyanobacteria) in 2011 were “four times higher at the City of Celina’s intake” and “even greater in 2012”. In addition, the HAB on Lake Erie in 2011 was considered the worst in 30 years (Public Water System Harmful Algal Bloom Response Strategy, May 2013).
New problems emerged in the detection of HABs in the spring of 2012 with the loss of the MERIS senor that remotely mapped HABs. The satellite would have provided great assistance in the “detection of HABs nearshore on Lake Erie and on inland water systems (especially HABs that do not form scums and are not as visually apparent).” (Ohio EPA, Public Water System Harmful Algal Bloom Response Strategy, May 2013). It is projected that no HAB satellite data will be available until late 2014.
This places a greater demand on water system personnel to maintain surveillance for HABs. However, visual assessment of bloom severity is not a particularly reliable indicator of the bloom’s effect on the water intake. It is often when blooms are dispersed throughout the water column, rather than concentrated in surface scums, that the intake toxin levels are high.
Visual assessment has become even more problematic with the observation of a Planktothrix rubescens bloom on an Ohio public water supply source in November, 2012. The Ohio EPA believes that Lima likely experienced a Planktothrix rubescens bloom on its new Williams reservoir. The Ohio EPA explains, “This species of cyanobacteria poses unique monitoring challenges because it exists at depth (potentially near intakes) and is not visual apparent at the lake surface during the summer months.” (2012 Public Water System Harmful Algal Bloom Summary, 2012). The bloom was detected prior to placing the new reservoir online, so the system was able to avoid any potential problems. This was the first time this species was observed on a PWS source.
Another type of HAB was discovered in Ohio during the summer of 2012. A red-colored Euglena bloom was detected on Dillon Lake. Euglena blooms produce an algal toxin called Euglenophycin that has a chemical structure similar to fire ant venom and have been linked to livestock fatalities. Currently, only two labs test for the toxin, Texas A&M and the National Oceanic and Atmospheric Administration. With limited information on the human effects of this algal toxin, the Ohio EPA will begin monitoring for the toxin in 2013 if any potentially toxin-producing Euglena blooms occur on a drinking water source.
With no current regulations, the task of monitoring is left to the voluntary efforts of PWSs and the state. As the City of Toledo and Clermont County can attest, removing cyanotoxins and the taste and odor compounds associated with HABs can be an economic burden. The City of Toledo spent $200,000/month for powdered activated carbon, while Clermont County estimates spending over $600,000 annually to replenish granular activated carbon. The Ohio EPA has conducted numerous studies, and their findings suggest that activated carbon is a valuable treatment component. With much still to be learned about the detection and treatment of HABs, the Ohio EPA is uncertain of what the future may hold for regulation and monitoring requirements.
HABs have a deep impact on the Drinking Water Industry, and as your resource for defensible data, we at Alloway strive to provide you with the latest news and EPA updates. To learn more about the Public Water System Harmful Algal Bloom Response Strategy, click on the link provided. You can also visit the Ohio EPA Harmful Algal Blooms website for more information.