Great Lakes Community Water Managers Remain Wary of Harmful Algal Blooms
Scientists have developed new technology to help protect drinking water in the Great Lakes Basin.
The city of Monroe, Mich., like so many coastal communities within the Great Lakes Basin, relies on water drawn directly from one of the five Great Lakes: in this case, Lake Erie.
Chris Knight, superintendent of Monroe’s water treatment plant, oversees the production and daily delivery of drinking water to 48,000 customers in the city of Monroe and surrounding communities.
They work in a facility originally built in the 1920s. The plant draws, on average, 7–7.5 million gallons of water directly from Lake Erie per day for treatment. On any given day 85–90 percent of the volume of raw water taken into the plant from Lake Erie is sent off for use by customers.
Knight and his 10 colleagues provide a watchful eye on the water treatment. Using a combination of real-time electronic monitoring systems and good old fashioned visual inspection. They monitor organic matter, pH and hardness levels to assure customers a steady year-round supply of safe drinking water.
“The pH of Lake Erie is normally in the 8.0–8.2 range,” Knight said. pH is a measure of acidity and alkalinity and is based on the balance between available hydrogen ions (acid) and hydroxyl ions (alkaline).
A Problem is Noticed in the Water
In a summer in the early 2000s, Knight and his colleagues noticed the pH of the raw water coming in from Lake Erie had risen to 9.0 — much more alkaline than they expected.
In water, carbon dioxide (CO2) is a major contributing factor in keeping pH low by combining with water to form carbonic acid. This weak acid is present in all surface waters and is vital to the health of lake ecosystems.
When Knight noticed their water’s pH rise to 9.0 and the water’s turbidity increasing, he became alarmed and took measures to bring the water pH back down into the desirable range, adding extra aluminum sulfate (alum) into the treatment system.
Alum is a routine step in the treatment process, mostly used to pull out organic matter and clear up the water. It can also be used, as it was this day, to bring down water pH.
Seeing such a rise in the pH of Monroe’s water led Knight to assume that a algae bloom in the lake was sopping up the CO2 as part of its photosynthesis, preventing carbonic acid formation and allowing the pH to rise.
The sudden appearance of a potentially toxin-producing species of algae in the water supply to Monroe’s customers was unexpected and alarming, suggesting that conditions in Lake Erie had changed that year allowing the bloom to develop. “The first time we saw one (algae bloom) was in the early 2000’s, but back then we thought it was regular algae. It would change the water characteristics, the pH would go up, but nobody thought it would be blue-green algae,” Knight said.
Blue-green algae hadn’t been a problem in the past for Monroe. There are numerous algae species in Lake Erie that are important to the ecosystem, including species of cyanobacteria, sometimes known as blue-green algae. Some blue-green algae can contribute to harmful algal blooms (HABs) by producing toxins that are potentially toxic to humans and animals.
Dr. Tim Davis, a molecular microbiologist at Bowling Green State University in Bowling Green, Ohio, researches how climate change will have an impact HABs. He looks at how the physiology and the genetic makeup of Microcystis, the major type of cyanobacteria associated with toxin production, responds to changing conditions in the environment.
“There is much about the ecology of Microcystis we don’t know. We know the root cause of blooms in freshwater ecosystems is, for the most part, anthropogenic nutrient loading; nitrogen and phosphorus are the two main drivers of the blooms,” said Davis.
Compounding the complexity of the algal bloom isse, not all cyanobacteria (blue-green algae) are Microcystis and not all species of Microcystis produce toxins. The finding of blue-green algae in a water supply does not necessarily mean toxins will be in people’s drinking water.
In 2012, Monroe installed a probe at their water intake after noticing an algal bloom influencing their city’s water quality. The probe provides real time readings of phycocyanin levels, one of the photosynthetic pigments found in cyanobacteria, as an indicator of blue-green algae at the intake pipe.
They now test for phycocyanin levels once per week, beginning the first Wednesday in July, continuing through November. If phycocyanin levels rise, indicating a cyanobacteria bloom, they collect raw water to test to see whether the cyanobacteria present are toxin producers.
“We have a cyanotoxin management plan implemented through Michigan’s Department of Environmental Quality. If there’s over five ppb in the water on Wednesday then we move to three times per week testing,” said Knight.
Fortunately for the citizens of Monroe, unlike unlike other communities, their water treatment plant uses ozone to disinfect the water and destroy the toxin. A toxin found in the water prompts Knight and his colleagues to maintain vigilance over the ozone-treatment of the water.
Using Technology to Predict Algal Blooms in the Future
Harmful algal blooms won’t necessarily have an impact on coastal community’s water supplies unless the blooms and toxins are present near the intake systems.
The notorious bloom of HABs in Lake Erie in 2014 that was such a concern for the city of Toledo, didn’t affect the citizens of Monroe in spite of the fact that the two communities are only 20 miles apart.
The ability to predict when blooms may develop in lakes and project their movement in the lake over time is the focus of the research of a multi-disciplinary group of researchers at the National Oceanic and Atmospheric Administration’s Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor, Michigan.
The GLERL scientists have developed technologies that allows them to predict the development of HABs in lakes and model their movement such that they can alert coastal community water suppliers of potential problems.
Most recently the scientists are collaborating with other researchers to develop a buoy possessing the capability to draw in a water sample, extract the DNA from algae and run testing to look for toxin producing capability of the organims in the sample. This information would be relayed via satellite back to the laboratory.
This ability, once implemented could act as an early warning system for Chris Knight and other water managers in the Great Lakes basin, to be on alert for HABs arriving at their water intake stations.
Dr. Mark Rowe at the NOAA laboratory emphasizes the importance of this mission for their laboratory. “NOAA GLERL is a research lab, so we work on developing new and improved models and data that can feed into the operational products, in addition to improved understanding of the Great Lakes and their ecology.”
The modeling work done by Dr. Mark Rowe and his colleagues has resulted in the development of a HAB Bulletin provided electronically to interested water managers to follow the course of seasonal algal blooms in Lake Erie.
It’s also just as important to understand that not all blooms in lakes are harmful: indeed regular blooms of microscopic plants and animals are necessary to the health and productivity of the Great Lakes.
Dr. Davis at Bowling Green University emphasized that not all blooms are bad. “The spring diatom bloom that occurs, those are absolutely critical in fueling the zooplankton populations which are preyed upon by bait fish which are preyed upon by commercial sport fish. Productive regions have great fisheries because they are just that: they are productive.”
In the end, understanding the complexity and nuance behind the ecology of the Great Lakes will lead to a better appreciation of the lakes themselves and a higher quality of life for people living near the Great Lakes basin.
