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Crews work on retrofitting an unused clearwell tank at the Maryville Water Treatment Plant last month to accommodate a granular activated carbon adsorber. According to city staff the project is ahead of schedule.

MARYVILLE, Mo. — The granular activated carbon adsorber project is ahead of schedule, and the Department of Natural Resources announced last week a new state and federal partnership to monitor source water quality.

The GAC adsorber being installed at the Maryville Water Treatment Plant will help filter out substances that adversely affect the taste and odor of drinking water. The $1.3 million project is an interim measure to mitigate long-running aesthetic issues with drinking water while city officials await the completion of a study to estimate the cost and feasibility of a long-term solution like a new water treatment facility.

At a City Council meeting Monday, City Manager Greg McDanel said that work on retrofitting an existing clearwell tank at the treatment plant is ahead of the scheduled Nov. 1 completion date.

Also at Monday’s meeting, the council approved the purchase and application of another 2,200 pounds of EarthTec algicide from Estate Management Services of Missouri for $53,350. Counts of cyanobacteria, also known as blue-green algae, were up again as of Aug. 16. PeopleService, the company contracted to run the city’s water treatment facility, conducts biweekly sampling of Mozingo Lake, the source for the city’s drinking water. High concentrations of cyanobacteria and other substances, like the compound geosmin, can cause taste and odor issues even after treatment.

The algicide treatment will be the fourth since May. Monday’s purchase will put the city over the $60,000 that had been budgeted this fiscal year for algicide treatments, McDanel said, and so the cost will be split between the water and sewer fund and the Mozingo fund. The fiscal year ends Sept. 30.

Once the GAC adsorber is installed, however, McDanel said algicide treatments should become much less frequent. Instead, the adsorber will be able to remove the offending constituents during treatment. Currently, contractor HDR Engineering recommends applying the algicide to the lake when monitoring shows concentrations of around 20,000-30,000 cells per milliliter of cyanobacteria in order to effectively combat objectionable taste and odor prior to treatment.

After the GAC adsorber is installed, McDanel said the city would likely only need to apply treatments if levels approached 100,000 cells per milliliter, which is the state’s threshold at which a recreational warning would be issued. The city previously reached that level in January 2020, warning visitors not to come into contact with the lake water.

Quality monitoring
In a press release last week, the Missouri Department of Natural Resources’ Soil and Water Conservation Program announced a partnership with the U.S. Geological Survey to install a state-of-the-art continuous water quality and stream flow monitoring gauge in the creek that feeds Mozingo Lake.

The new gauge will measure turbidity, temperature, dissolved oxygen and nitrate levels among other parameters.

Missouri DNR and the USGS are two of several agencies that have been working regularly with city officials and others as part of a broad coalition assembled to identify the causes and possible solutions to the persistent algae problem. The harmful algae blooms are fueled by excess nutrients entering Mozingo Lake, negatively impacting water quality, threatening aquatic ecosystems and potentially producing toxins that can be harmful to animals and people.

“This new gauge will collect water quality data in 15- to 60-minute intervals for the next three years,” said Jeremy Redden, environmental manager with DNR’s Soil and Water Conservation Program, in a statement. “The data will help to establish a quality baseline for the water coming into Mozingo Lake. As best management practices are implemented on the surrounding farm land, we hope to document the resulting improvements in water quality.”

The Mozingo Creek monitoring gauge installation builds upon action taken by the Soil and Water Districts Commission last April when the commission allocated $200,000 through its cost-share program to install best management practices, including cover crops and field borders, on the land that drains into Mozingo Lake. These measures are designed to help prevent or control soil erosion and protect the lake’s water quality.