The floating mats of the genus Microcystis, photographed in late August at Sojourner Truth Park in New Paltz. These algae can cause illness, particularly when ingested. People are warned to thoroughly wash themselves, their equipment and their dogs as soon as possible after any contact with this bloom. (Julie O’Connor | New Paltz Times)
The DEC has listed the Wallkill as “confirmed with high toxins” following water sample tests conducted last week on portions of the river that have turned bright green since experiencing a toxic algae bloom in late August.
According to a joint release by Riverkeeper and the Wallkill River Watershed Alliance, one sample revealed the presence of a toxin at 25 times the “high toxin” limit. That sample was taken at Sojourner Truth Park in New Paltz on Aug. 26. Another sample taken three days later was ten times the limit.
The algae bloom has been visible from Gardiner to Rifton. Causes include high temperatures, slow or stagnant water, and an overabundance of nutrients from sewage and runoff.
These floating mats are part of the genus Microcystis, which can cause illness, particularly when ingested. Microcystis is one of three genera of freshwater cyanobacteria (also known as blue-green algae) that are being tracked widely as sources of harmful algal blooms. The DEC has advised residents (and their pets) to avoid the river until the bloom clears up.
Representatives from the watershed alliance and Riverkeeper said the causes of the algae bloom that hit the river this year and in 2015 should be addressed.
“This is the Wallkill River’s bright green plea for help,” said Dan Shapley, Riverkeeper’s water quality program manager. “We are calling on local, state and federal officials to define the causes of this harmful algae, and to start healing this river.”
“This situation is appalling and deeply disturbing, said Jason West, director of the Wallkill River Watershed Alliance and former New Paltz village mayor. “By ignoring climate change and dumping large amounts of nutrients into the river, we’ve transformed it into a river of poison.”
Here’s a timeline provided by the organizations:
August 26, 2015: A large algae bloom was observed on the Wallkill River in New Paltz, covering approximately two miles downstream of Sojourner Truth Park. Samples analyzed by a SUNY Rockland biologist working with Wallkill River Watershed Alliance identified potentially harmful algae genera. Based on a visual assessment, the New York State Department of Environmental Conservation’s Harmful Algal Bloom program listed the bloom as “suspicious.”
June 2016: Wallkill River Watershed Alliance and Riverkeeper begin monthly monitoring of the Wallkill River for nutrients and algae, working with a grant from the NYS Environmental Protection Fund, via the DEC’s Hudson River Estuary Program.
August 15, 2016: Algae was observed in the Rifton area. Samples analyzed by SUNY Rockland and SUNY Ulster biologists working with the Wallkill River Watershed Alliance confirmed the presence of the genus Microcystis, a potentially harmful cyanobacteria also known as blue-green algae.
August 24, 2016: An algae bloom affecting a stretch of the river from New Paltz to Rifton was first observed. Analysis by SUNY Rockland and SUNY Ulster biologists confirmed the presence of Microcystis.
August 25, 2016: After confirmation of observations, and consultation with Department of Environmental Conservation’s Harmful Algal Bloom program, Wallkill River Watershed Alliance and Riverkeeper warned the public to avoid contact with the Wallkill where algae are visible. DEC lists Wallkill River and Sturgeon Pool Harmful Algal Bloom as “suspicious.” Central Hudson’s recreation beach on Sturgeon Pool is closed on advice of Ulster County Department of Health.
August 31, 2016: DEC lists Rondout Creek harmful algal bloom as “suspicious” based on photographs submitted by Riverkeeper at DEC fishing access site on Creek Locks Road, downstream of Wallkill River confluence.
September 1, 2016: SUNY ESF, part of DEC’s Harmful Algal Bloom monitoring program, completes first analysis of three samples (gathered at Sojourner Truth Park in New Paltz and at Rifton) submitted by Riverkeeper and Wallkill River Watershed Alliance, confirming high blue-green chlorophyll-A levels in excess of DEC thresholds, and dense Microcystis in all three samples. DEC lists Wallkill River Harmful Algal Bloom as “confirmed.”
September 7, 2016: Department of Environmental Conservation communicates results of same three samples, analyzed by SUNY ESF for levels of microcystin, a toxin produced by some strains of Microsystis species. The two samples taken at Sojourner Truth Park in New Paltz exhibited levels of microsystin, a toxin, above the DEC “high toxin” threshold of 20 µg/l (microgram/liter), with levels of 517 µg/l from a sample taken on August 26 and 269 µg/l from a sample taken on August 29. The Rifton sample showed detectable levels at 3 µg/l, below the DEC threshold.
September 9, 2016: Based on results of toxin analysis, Department of Environmental Conservation lists Wallkill River Harmful Algal Bloom as “confirmed with high toxins.”