OWASCO — Cooler temperatures appear to have kept harmful algal blooms out of Owasco Lake for most of the month of August, but that was not keeping water treatment operators for the city of Auburn and town of Owasco complacent.
Last year, toxins from the blooms showed up in the treated drinking water in mid-September for about half of Cayuga County's residents. Called microcystin, the toxins can cause adverse health effects, though levels never reached a do-not-drink order.
Auburn's chief water plant operator, John West, said earlier this week that they had not seen any algae or toxins enter the plant yet, but Thursday's 60-degree temperatures didn't sway West, either.
"If it stays clean until Nov. 30, then maybe I'll feel like we're out of the woods," he said, shaking his head.
But on Friday night, the Cayuga County Health Department announced low levels of toxins were found in a sample of the city's raw water and the carbon system would be activated as a precaution. No toxins were found in the city's treated water or in the town of Owasco's water.
The city installed its powder-activated carbon treatment system in the upper pumping station located in Emerson Park. West and Director of Municipal Utilities Seth Jensen said they're still working on finishing up a few things, but the treatment itself was ready to go.
How does it work? West said a 900-pound bag of powder-activated carbon is fork-lifted up onto a funnel-like structure. The carbon is released into pipes carrying the raw lake water underground to the water treatment plant. West said the carbon can be released at rates specific to what the toxin levels may be.
For now the system is set to treat the toxin at 20 parts per million, which West said equates to about one bag every 30 hours. The city distributes between four and five million gallons of water per day. When the city ran the system last, it took the carbon between an hour and an hour and a half to show up in the water treatment plant. Jensen said the recommended contact time for the raw water with the carbon is about 45 minutes.
The Cayuga County Health Department had ramped up its water testing to twice per week, and was planning to increase to daily should the toxins appear. But until Friday, things had been quiet, perhaps deceptively, on the lake. After a flurry of blooms in July, the Owasco Lake Watershed Inspection Program was concerned about having used six of its 36 harmful algal bloom test samples currently allotted through the state Department of Environmental Conservation. The DEC has not listed Owasco Lake on its harmful algal bloom notifications page in weeks.
Costing more than $2 million in total, neither the town nor the city wanted to have to test their treatment systems for the real deal.
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"If microcystin were to show up, we would be ready to go and start treating it," Jensen said prior to Friday's test result. "Hopefully it works great. Hopefully, we don't have to use it."
GHD Consulting Services Inc., the engineering firm working with the city and the town, has set up a water column toxin testing lab in both plants. If microcystin shows up in the raw water, an engineer will test four additional treatment methods, including different kinds of granular activated carbon, the kind of carbon the town of Owasco is using.
Owasco's Water Treatment
Owasco Town Supervisor Ed Wagner said the town's treatment system has been installed and is working, though they have not seen any toxins or algae entering the plant.
With the town's system set up differently from Auburn's, there's no long, underground pipes to give the carbon time to treat the water. Instead, the town has two, approximately 30-foot tall containers filled with 20,000 pounds of granular activated carbon combined. Once the water is treated through the traditional system, it flows into one underground concrete well and up into the carbon tanks. After a minimum of 20 minutes of contact time, the water flows into a second well before going out for distribution.
The two tanks treat about 800,000 gallons of water per day, which Wagner said more than meets the town's peak demand. In the summer months, the plant may deliver as much as 600,000 gallons of water per day, but the average is about 450,000 gallons per day.
"Ninety-nine percent of the time, it (microcystin toxins) got filtered out last year," Wagner said. "Only a few times did it have any trace of harmful algal bloom (toxins) in it. This is just, this has got to remove the remaining material."
Both the town and the city are on a month-to-month equipment rental basis for their installations now. Jensen said Auburn's rent is going toward the equipment's purchase, should it prove to be effective. Wagner said if the town's system works, he would want to situate the pipes underground and build a structure to house the carbon tanks. He is considering keeping the carbon system, as the cost for removing it and potentially reinstalling it is looking greater than purchasing it.
The granular activated carbon could last between five and 10 years, too, before it needs to be switched out. If algae never comes into the plant for it to be tested, it's still another filtration method.
"Our goal is to have the best drinking water in the state," Wagner said.