As people move towards the rivers for recreation and some cooling respite from the August heat, they need to be aware of the ever-growing stretch of harmful algal bloom (HAB) that has spread over 14 miles from the Wallkill River to the Rondout Creek in Ulster County. The Wallkill and Rondout combine to form the largest tributary to the tidal portion of the Hudson River and are heavily utilized for passive recreation, particularly during the summer months.
According to Dan Shapley, co-director of science and patrol for Hudson Riverkeeper (www.riverkeeper.org), a not-for-profit clean water advocacy group for New York State waterbodies, the toxic algal bloom has “overtaken parts of the Wallkill River and Rondout Creek, putting recreational users at potential risk from toxins produced by the algae.” Contact from kayaking or fishing might cause some skin irritation, but immersion into harmful algal blooms, according to the New York State Department of Environmental Conservation (DEC), can cause vomiting, nausea, diarrhea, allergic reactions or breathing difficulty, if there is prolonged contact or the toxic algae are digested.
Most algae are completely harmless and are a vital part of the food web, but certain types of algae, fed by dense amounts of nitrogen and phosphorus, grow rapidly and form blooms that can cover portions of a lake or waterway and post a toxic threat to humans and pets. Looking at a bright-green film of HAB near Gardens for Nutrition, next to the sewage treatment plant, Shapley pointed out that the algal bloom can be “recognized by its spiral patterns and fluorescent-green appearance and spilled-paint look.” He added that that the DEC has an entire section on its website dedicated to ways of recognizing and reporting these toxic blooms, including information on what is being done to try to combat them.
“We’ve had a lot of reports of algae blooms in the past two weeks, and it’s right here,” he said, pointing to a large green sheen on the Wallkill. “And people are recreating in it, which is understandable, because it’s been so hot and it’s natural to want to go to the river and swim or fish or kayak; but this is toxic.” He said that dogs are most often at risk because they like to swim and ingest the water. “Swimmers can also experience gastrointestinal problems if they ingest the infected water. But we don’t know a lot about the long-term effects of these toxins, so it’s best to avoid it if you can.”
Asked what the causes of the algae blooms are, Shapley cited a confluence of three elements. “These are created when there is an overload of nutrients in the water. Nutrients are a good thing until we have too much of them, and they feed these guys,” he said while in waders, taking samples from the nightmarishly green swirls in the Wallkill. “The combination of having sewage water treatment plants along the Wallkill River here and in Montgomery, Walden, Florida…even though the wastewater is treated, [it] still pumps a lot of phosphorus into the river. That in combination with agricultural runoff, which is also all along the Wallkill and Rondout Creek, adds to the nutrient overload. And then we have a year when it’s hot and dry.”
Global warming, he explained, only exacerbates the problem, as hot, dry weather extremes help the waterways heat up, so that we have an algal bloom soup. “The water is low because of the drought; and then we have dams along the river, which slow down the natural flow, and the algae grows quickly.”
It was New Paltz Kayaking, a local business centered on the joys of kayaking and mountain biking in the New Paltz area, that first reported the suspicious blooms to Riverkeeper on August 11. According to Shapley, Riverkeeper “engaged a number of individuals and organizations to help document, study and respond to the algal bloom, including Hudson River Watershed Alliance, Cary Institute, Wallkill River Watershed Alliance, Bard College and the DEC.” He said that samples gathered by Riverkeeper at Sturgeon Pool in the Wallkill and the Creek Locks Road fishing and boating access site in the Rondout were analyzed by John Gotto, professor emeritus from SUNY Ulster, and confirmed to have microcystis, the group of cyanobacteria that can produce toxins. The DEC told Riverkeeper that it had posted warning signs at several access points this week.
“The observed location and extent of the algal bloom has shifted since it was first observed on August 11,” said Shapley. To date, the toxic bloom has been observed primarily at points along a 14-mile stretch from the vicinity of the River-to-Ridge trail and Gardens for Nutrition in New Paltz, downstream (north) to DEC’s Creek Locks Road public access site on the Rondout Creek, west of Kingston. “The bloom has not been visible at all locations throughout this stretch on all days or all times, and the extent has shifted from day to day and even hour to hour,” he noted.
What is the cure? There is something called a “nutrient diet” that can be implemented by various governing jurisdictions to ensure that waterways are not overwhelmed by nutrients that lead to HAB, but the precise remedy, according to Shapley, “needs to be worked out by analyzing the detailed water testing that New York State has been doing since 2016.” Bard College is also collecting data and doing research on the short- and long-term health impacts of HAB exposure.
In the meantime, the DEC recommends that bathers and water recreationalists get to know what the harmful algal blooms look like and report them to the DEC Suspicious Algal Bloom Report Form. “If possible, attach digital photos (close-up and landscape to show extent and location).” Or you can e-mail firstname.lastname@example.org and report any health symptoms to the New York State Health Department at email@example.com.