Posted on February 6, 2018 by Virginia C. Robbins
Frank DeOrio knows a lot about protecting drinking water. For more than 25 years, Frank was Director of Utilities for the City of Auburn located in the pristine Finger Lakes region of Upstate New York. He was responsible for the water supply drawn from Owasco Lake and the protection of the lake’s watershed. During Frank’s tenure, the City won awards for the best water in the state and the U.S.
Frank and I recently discussed his concerns about the potential impacts to drinking water from summer algal blooms in our region’s lakes. Algal blooms can occur when spring rains flush nutrients, for example, phosphorous, into waterbodies. Summer temperatures raise water temperatures, creating optimum growth conditions.
Owasco Lake, September 18, 2017
Summer algal blooms now occur in more lakes, their duration has increased, and they are producing toxins that pose health risks to the public when ingested or during recreational contact. These toxins are not easily treated by water suppliers because the technology to treat one toxin may not be effective for another. And unlike bacteria, boiling water does not remove these toxins.
In 2017, harmful algal blooms (HAB) occurred in all 11 of the Finger Lakes, reportedly for the first time. Blue-green algae are cyanobacteria and they can produce several species of cyanotoxins. What is disturbing about the recent HAB outbreaks is that some classes of these cyanotoxins (e.g., microcystins), are particularly toxic. If present at high concentrations, they can be difficult or impossible to treat using the technology of most public water systems. One of these is Microcystin-LR, a liver toxin that is considered one of the more toxic. These toxins can also cause skin, digestive system and other health issues.
Mycrocystin-LR has been identified in raw water drawn from Owasco Lake and Skaneateles Lake, both jewels of the Finger Lakes. And Owasco Lake provides drinking water to more than 50,000 customers. In 2016, the City of Auburn was using filtration to treat its raw water. When the level of Mycrocystin-LR increased, the City considered moving the location of its water intake away from the area of the lake containing the toxin. But would the new intake remain safe if the toxin shifted location? The City decided against moving the intake and instead added carbon filtration.
Skaneateles Lake is the primary water supply for the City of Syracuse and surrounding communities. The water authority operates under a “filtration avoidance” authorization. After a severe storm on July 1, 2017, phosphorous levels in the lake rose, resulting in algal blooms, and Microsystin-LR was then detected in the raw water pumped from the lake. The levels were low enough that treatment was not required and the toxin was not identified in the water that reached customers. Nonetheless, the presence of this toxin in the raw water is a disturbing development.
These examples are lakes in my area. But similar algae toxins and blooms are occurring in New England states, including New Hampshire and Maine.
The broader challenges? The science around algae toxins is emerging. Further, there are no federal or state drinking water standards for microcystins (though there are health advisory guidelines published by USEPA and some states). Water treatment plants are generally designed to avoid taste and odor concerns and to manage the most commonly tested algae toxins. The next generation of plants will need to have more flexible designs to accommodate advanced treatment technologies. And water authorities will need to consider spatial needs, hydraulics, connections, utilities and process control for these technologies.
Frank’s concerned. So am I. It may get worse before it gets better. While we wait for science, regulatory efforts and focused treatment technology to develop, at least municipalities can take steps to control the potential for toxic algal blooms by a combination of runoff control, nutrient reduction and stream-bank restoration. Why wait to build that bridge from troubled waters to cleaner lakes?