The type of crisis that forced Toledo to shut off its taps earlier this month is a long shot to happen here, but the potential for toxic algae to harm this region’s massive supply of clean water has prompted one agency to update its monitoring protocol.
The Miami Conservancy District works to preserve water quality in the region, but until recently it had not been concerned about microcystin, the cyanobacteria that prompted the state’s fourth-largest city to warn its citizens to not drink their water for more than two days.
“It’s tended to be more of a lake issue and folks have not been looking for (harmful algal blooms) on rivers. But we are going to begin to do microcystin screening at some of our monitoring stations very soon,” said Mike Ekberg, the conservancy district’s manager in charge of monitoring and analysis.
Ekberg ordered a testing kit this week.
“If we have had releases of algal toxins in the water, it’s largely an unknown,” he said. “It could potentially pose a threat to wells that are not installed very deep in the aquifer right next to the river. We don’t want to go there.”
Aquifer holds 1 trillion gallons of water
The Great Miami Buried Valley Aquifer, estimated to hold at least 1 trillion gallons of water, lies beneath 15 counties. While it likely won’t be affected by toxic algae, which requires sunlight to thrive, it is considered to be “under the influence of surface water.” That led the Ohio Environmental Protection Agency to declare that parts of the aquifer have a “high susceptibility to contamination.”
That designation was made partly because the aquifer lies close to the surface and has only a thin layer of clay to protect its gravel and sand base.
The Ohio EPA also has placed parts of the Great Miami River in Dayton, Piqua and Sidney on its “watch list” due to high nitrate and pesticide indicators.
Another concern is E. coli. In a 2013 report, all eight conservancy sampling stations had high E. coli readings. Wolf Creek had the highest readings, an average of 1,925 units per 100 milliliters of water. That is more than six times the state limit for recreation contact.
A conservancy district report released last week indicated that nitrate concentrations at all of its sampling stations exceeded recommended nutrient targets last year. The highest concentration was collected from the Stillwater River at Englewood. The major source of nitrates is fertilizer runoff, but failing septic systems add to the problem.
“We have some very high-quality aquatic habitats, but the nutrient issue is systematic of what’s going on across this entire nation, and the Great Miami River is no different,” Ekberg said. “It’s over-enriched with respect to nitrogen and phosphorus.”
Treating the water
Public water systems are required to treat water before it is sold to the public. Although much of the water pumped directly from the aquifer might be safe to drink, extra precautions are taken.
“By the time it gets to a customer’s tap, it’s been through multiple lines of testing and oversight and regulation from the Ohio EPA,” said Brianna Wooten of Montgomery County Environmental Services. “It’s very well-regulated.”
The county is the distribution arm in the process, although some municipalities — such as Huber Heights, Englewood, Miamisburg and Vandalia/Tipp City — pump their own water.
The county buys treated water from the city of Dayton, which has two treatment plants — the Miami plant near Kittyhawk Golf Course and the Ottawa plant across the highway from Dayton Children’s Hospital.
Each plant has the capacity to treat 96 million gallons per day, but their combined average daily output is closer to 64 million gallons, said Phil Van Atta, a manager at the Miami plant.
“Demand has dropped a great deal since 2007 and the recession and the automobile industry shutting down plants,” Van Atta said. “If we had to shut one plant down, we could increase the production rate at the other plant. It’s good to have that redundancy.”
The Miami plant was built in 1965, the Ottawa plant in 1953. The city’s water department is self-sustaining, bringing in enough money to cover its costs, including upgrades.
“We invest in our infrastructure, including the $160 million invested to replace sewer and water pipelines,” Van Atta said.
One of the city’s upcoming projects is the replacement of its large sand filters. Each bay is 32 feet by 20 feet and the filtration process is the last stage of treatment before clean water is pumped to a pair of 10-million gallon reservoirs and other storage facilities.
The treatment process begins when water is procured from the aquifer by more than 100 production pumps that reach down anywhere from 40 to 150 feet. They are located near the Miami and Mad rivers and typically pump about 1,000 gallons per minute.
The water is piped to the treatment plants where lime is added to soften the water. Carbon dioxide adjusts the pH balance and doses of fluoride help prevent tooth decay. Chlorine is added to kill bacteria.
Dayton does not use powdered activated carbon, which was credited with bringing Toledo’s water system back online.
“We have the capacity to feed powdered activated carbon at the Miami plant, in case we have a problem with something like a pesticide spill or train spill, something we couldn’t strip with our aeration systems,” Van Atta said.
Plenty of testing
Van Atta isn’t concerned about toxic algae, but there are plenty of reasons to test water on a regular basis.
“For us, the greatest concern is the volatile organic compounds (industrial solvents, leaking landfills),” he said. “That’s a legacy we’ve had to live with. Back in the early ’80s there were levels that, frankly, were too high.”
A source-water protection program includes the use of early-warning monitoring wells, from which water can be drawn and tested in a mobile lab.
The city employs engineers, toxicologists, microbiologists and chemists to help keep its water safe. And after the product moves to the distribution phase, the county tests it twice monthly at 100 locations.
Public water systems test for many substances, from fluoride and nitrates to lead and copper. Dayton met all standards for drinking water in 2013. It did have three samples out of 1,503 test positive for coliform bacteria.
The county, which pays for its testing through water and sewer bills, says the water it sells is tested “more frequently and consistently than bottled water for quality and safety.”
Even byproducts of the chemicals used to treat the water are tested. Chlorine, for example, produces haloacetic acids, trihalomethanes and chloroform, so chlorine use is carefully monitored.
“The levels are so low that the EPA has reduced our monitoring a couple of times, including this year,” Van Atta said.
All of the testing completes what the aquifer starts, making the original source of local drinking water much cleaner than what is pumped from Lake Erie.
“Our aquifer is almost like the first point of treatment, even before the water goes into the treatment plant,” Ekberg said.
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