Johnstown, Cuts Taste and Odor Compounds with Ultrasound Technology

Background  

The Town of Johnstown, Colorado operates a 6.2 MGD conventional surface water treatment plant supplied by two primary reservoirs: Lone Tree and Town Lake. The utility has historically faced seasonal cyanobacteria along with recurring taste and odor events, managing these issues with PAC (Powdered Activated Carbon) at Lone Tree and, since 2022 with GAC (Granular Activated Carbon) vessels. However, because PAC feeding was not available at Town Lake, the utility sought an additional source-level strategy to reduce Geosmin and MIB (Methylisoborneol) before they reached the plant. At the treatment plant, the process included dissolved air flotation, aluminum sulfate for pretreatment, and sodium hypochlorite for disinfection.

Therefore, to proactively address these challenges, Johnstown installed two LG Sonic MPC-Buoy systems on Town Lake in 2022, enabling continuous water quality monitoring and ultrasound-based algae control. The treatment plant later applies dissolved air flotation, aluminum sulfate pretreatment, and sodium hypochlorite disinfection as part of its overall process.

The Problem  

1- Seasonal Taste and Odor Events
Cyanobacteria-related taste and odor compounds; particularly geosmin and MIB (2-Methylisoborneol) regularly affected the raw water entering the treatment plant. PAC dosing was available only at the Lone Tree source, leaving Town Lake without a direct mitigation method. Taste and odor episodes required additional operational attention and created seasonal unpredictability in chemical use and treatment processes.

2- Data Limitations for Treatment Adjustments
Before deploying the MPC-Buoy systems, the utility lacked real-time visibility into algae trends and precursor conditions. This limited their ability to implement timely treatment changes. Even after deployment, limited operator availability restricted how frequently operational responses could be adjusted based on buoy data.

Measurable Results  

Since installing the MPC-Buoy systems in 2022, Johnstown has observed encouraging early outcomes, especially during the 2025 season:

• Late-season 2025 results showed substantially reduced taste and odor compounds in Town Lake.
• Operators observed reduced floating algae and more stable summer conditions in 2025.
• Lower taste and odor levels may allow greater reliance on Town Lake, supporting more energy-efficient operations.
• PAC has not been used at Lone Tree since 2022, simplifying operations and removing respirator-required handling.

John Ferguson, Johnstown’s water superintendent states:

“I feel like we are finally seeing a positive change in Town lake this year, based off of Geosmin/MIB results throughout 2025.”

Fig.1: Turbidity levels dropped (May-Oct 2025)

Turbidity remained low and stable from May to early October 2025, with only brief peaks during storm events. Although fluctuations increased after mid-July, values still trended downward toward season’s end, indicating improving clarity and fewer suspended particles heading into autumn.
Fig.2: Chlorophyll-a levels dropped (May-Oct 2025)

Chlorophyll-a levels remained relatively low throughout the season, with only brief natural peaks. Although fluctuations increased after early summer, overall concentrations declined toward autumn, indicating reduced algal biomass and improving system stability.

Wayne Ramey, president and owner of Ramey Environmental Compliance, Inc., oversees 32 wastewater and 40 water treatment facilities across Colorado. With over 30 years of experience in the water treatment industry, he has extensive hands-on expertise in managing algal blooms and their impacts. He states:

“We couldn’t believe how fast it worked in as little as four weeks. Normally, during heavy months, we would run 750 to 1,000 pounds of pack [algaecide] a day and in the first year of ultrasonic treatment, we didn’t have to add anything at all.”

Discussion  

Although early years showed gradual adjustments, 2025 marks the first season where Town Lake demonstrated a clear positive shift, aligning buoy-based monitoring with meaningful operational outcomes.

Chemical-Free Sustainability Benefits: The move away from Powdered Activated Carbon (PAC) aligns with Johnstown’s broader sustainability priorities:

• Reduced operator exposure to fine activated carbon particles
• Simplified treatment operations
• Lower environmental footprint from chemical reduction

Clarity and Aesthetic Conditions: Operators noted that water clarity remains high but diminishes at about one foot below the surface; a trend they continue to monitor through buoy sensors and plant observations.

Conclusion  

The experience in Johnstown demonstrates how combining continuous monitoring with ultrasonic algae control can transform taste and odor management at the source. As operators refine their treatment decisions using real-time buoy data, results from the 2025 season offer the clearest evidence yet of improved conditions in Town Lake.

With cyanobacteria levels suppressed, geosmin and MIB concentrations trending downward, and a reduced need for PAC, the utility is progressing toward a safer, more efficient, and more sustainable drinking water strategy.