The Esopus Creek at Saugerties Beach and nearby areas is looking a lot clearer, with a reduction of the weeds that have been choking it over the past few years. The clearing follows the cutting of the weeds with a specialized boat. However, environmental scientist Leslie Surprenant, who has been studying the Creek for the past three years, has questioned whether the weed-harvesting program actually explains the improvement.
Surprenant, a member of the Saugerties Environmental Advisory Commission and the Ulster County Environmental Advisory Council, has studied Environmental Science and Forestry, worked as a fish biologist in Saratoga Springs, moved here to take a job as a fish biologist in New Paltz and is also an environmental biologist. She retired in 2016, “and I have stayed pretty busy with volunteer projects.” One of those projects has been a study of the Esopus Creek and the weeds that choke it, she said. The Creek is “dear to our hearts for recreation, economic development, aesthetic purposes. I think we also all know that it has an aquatic vegetation problem.”
A particular problem is an invasive Eurasian milfoil. The town and the Conservation Advisory Commission worked with the State Department of Environmental Conservation coordinator to look at options for dealing with the plant. Among the options were chemical treatment; smothering out the plant, which has been done successfully in Lake George; and mechanical harvesting. “Of all those treatments, the most effective would have been chemical treatment,” Surprenant said. However, the speed of flow of the watercourse can render chemicals ineffective, “so we were left with the action of harvesting on the Creek.”
In 2019, the harvester was first used around the beach area; in 2020 the village bought the harvester, “and it has operated over a wide area in 2021 and 2022.”
In order to find out how well the harvester is doing its job, Surprenant set up 40 monitoring sites along a two-mile stretch of the Creek. She checked the sites in July 2020 and July and August of 2022. The idea was to measure the health of the ecosystem and the change resulting from the harvesting.
The study covers about an acre of the Creek, with one site at approximately 20 feet deep, Surprenant said. Measurements included depth, water temperature, species of plants and fish. She collects samples and makes measurements from a canoe, using mostly homemade equipment: bricks and rope. She determines the density of the vegetation and which species are there. Plants are important, providing oxygen, habitat and food for aquatic creatures and nutrients when they break down, Surprenant said.
Fragments of Eurasian milfoil can stick to boats, especially in July and August, Surprenant said. “Each little fragment can start a new plant.” Another species, water chestnuts, was not in the survey area, but is a problem around the Village Beach. It grows very densely in the cove near the village, and has therefore been a concern. This plant can be controlled by hand-pulling because it is an annual, and must start again each year.
The data show “a significant change between 2020 and 2022 in both the harvested and the unharvested areas,” according to Surprenant. Among rooted plants, the reduction was 76 percent in the harvested area, but it was also 76 percent in the unharvested area, “so we know it’s not just due to the harvester.” There has been a reduction in the milfoil, and it has been statistically positive.
One factor that may explain the reduction in aquatic plants in both harvested and unharvested areas is turbidity from Ashokan Reservoir releases. “Could low light penetration in 2021 have suppressed plant growth enough so they wouldn’t reproduce as they normally would, and had an effect in 2022?” Surprenant asked. It’s possible, but in science, sometimes the more information we get, the more questions we have, she said. “Could it be a combination of harvesting and turbidity? Is it something else?”
Surprenant recommended that her vegetation surveys be coordinated with the harvests between the Village and the Town. She volunteered her time, but she needs more complete harvest data from the village. She plans to reduce the number of sites, as the upstream sites did not have enough vegetation of the type she is studying. Information from the Village would be helpful, and in particular, “If the harvester does not pull the plants from the roots, that would be important to know.” It would also be helpful to know what species are being pulled by the boat. She hopes to do a survey every year, or at least every other year, and report the results to the State database, which she has done.
Councilman Zach Horton said that from the time he looked at Surprenant’s first report, he was impressed with the amount of time she dedicated to it, “and I could imagine what it would cost the town and village to conduct this kind of thing, so I thank you for that.” Supervisor Fred Costello said that people agree that the Creek definitely looks better, but it may not only be the harvester operation. “You have a suspicion that the turbidity and the lack of light contributed.” Surprenant agreed, because her data show similarities between the harvested and the unharvested areas. She added that the 80 tons reported last season are “a drop in the bucket. It is not ineffective, but it would be most effective if the harvester is indeed pulling the plants out by the roots.”
Costello said that he looks forward to seeing more data to determine how best to deal with the weed problems in the Esopus Creek.