Last August, a spike in HABs around its water intake crib in western Lake Erie caused Toledo to issue a ban on drinking water, which lasted several days. HABs produce a toxin called microcystin, which, even in minuscule amounts, can be harmful.
In Clermont County, HABs on Harsha Lake in June 2014 led to public health advisories warning against swimming in the lake. (The growth in algal blooms is partly attributable to nutrient runoff, and the Clermont County Soil and Water Conservation District is working on a number of measures with local farms to address that.)
The Clermont County Water Resource Department has measures in place to protect the safety and quality of the water drawn from Harsha Lake, said Water Resources Director Lyle Bloom.
“We have multiple barriers at the Bob McEwen Water (BMW) Treatment Plant to effectively prevent or remove algal toxins,” said Bloom. These include:
• The plant’s intake structure, which draws water from the lake, and has three different levels. Algal blooms occur near the surface, so a deeper intake screen can be used to avoid the affected water.
• A combined coagulation, flocculation, sedimentation, and filtration treatment. In laymen’s terms, this standard treatment removes particles from water. “This method of treatment is extremely effective for removal of algal cells,” said Bloom.
• Granular Activated Carbon (GAC) treatment technology, which traps contaminants and is a primary way to remove algal toxins.
• Disinfecting the water at the plant with chlorine, which will inactivate microcystin.
Clermont County collaborates with the U.S. Environmental Protection Agency, the Ohio EPA, the Ohio Department of Natural Resources and the Army Corps of Engineers to monitor Harsha Lake for algal blooms and test for algal toxins once a bloom is detected, said Bloom.
When samples collected in the lake exceed the current Public Health Advisory level of 6 micrograms per liter, the Ohio EPA samples untreated and treated water samples from the plant. To date, no toxins have been detected in the treated water, said Bloom.
Only a portion of the water used each day by Clermont County customers is produced at the BMW plant. Clermont County also owns and operates two additional water treatment plants that draw water from wells. The groundwater drawn from the wells is not susceptible to algal toxins. The current demand for water in the Clermont County Water System can be met utilizing only these two sources if necessary.
For more information, contact Mark K. Day, at 513-732-7945 or firstname.lastname@example.org
(Photo: Harsha Lake)