CASE STUDIES
City of Marysville
A proactive algae management program eliminated harmful algal bloom events and microcystin detections while protecting the city’s drinking water supply.
THE CHALLENGE
Harmful Algal Blooms Threaten Drinking Water Operations
The City of Marysville operates a nearly 100-year-old, 4.3 MGD lime-softening water treatment plant supplied by both groundwater and a 110-acre surface water reservoir. Because surface water is less expensive to treat, the city prefers it as its primary source.
In 2017, following reservoir improvements, the city experienced its first harmful algal bloom (HAB). Microcystin concentrations exceeded Ohio EPA thresholds and eventually reached 2.69 µg/L. Detectable levels were later found in finished drinking water, forcing the city to temporarily rely on 100% groundwater treatment while evaluating long-term control options. Traditional copper sulfate treatments presented operational and sediment accumulation concerns, while ultrasonic technologies were cost-prohibitive.
In 2017, following reservoir improvements, the city experienced its first harmful algal bloom (HAB). Microcystin concentrations exceeded Ohio EPA thresholds and eventually reached 2.69 µg/L. Detectable levels were later found in finished drinking water, forcing the city to temporarily rely on 100% groundwater treatment while evaluating long-term control options. Traditional copper sulfate treatments presented operational and sediment accumulation concerns, while ultrasonic technologies were cost-prohibitive.
THE APPROACH
Proactive Algae Control Before Blooms Develop
In 2018, the city implemented a preventive management strategy using EarthTec® liquid ionic copper algaecide. The product was selected for its rapid dispersion, ease of application, lower copper concentration, and improved performance compared to traditional copper sulfate treatments.
Treatments were applied by boat every 2–3 weeks once water temperatures exceeded 50°F. Rather than responding to active blooms, the program focused on preventing algae growth before harmful bloom conditions could develop.
Treatments were applied by boat every 2–3 weeks once water temperatures exceeded 50°F. Rather than responding to active blooms, the program focused on preventing algae growth before harmful bloom conditions could develop.
Long-Term HAB Prevention and Source Water Protection
The EarthTec® program successfully prevented harmful algal blooms and microcystin detections while maintaining a cost-effective source water management strategy.
0
HAB EVENTS SINCE TREATMENT BEGAN
0
MICROCYSTIN DETECTIONS IN 100+ SAMPLES OVER 4 YEARS
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