The invasive aquatic plant species known as “rock snot” has been found in the upper Kayaderosseras Creek, Saratoga County’s most-popular trout stream.
The state Department of Environmental Conservation on Wednesday announced it had confirmed the presence in the creek above Rock City Falls of Didymosphenia geminate, or didymo, known more commonly as rock snot because of its appearance.
State officials said the alga, considered a nuisance species, has the potential to overwhelm other plants in the stream and affect fish habitat.
The Kayaderosseras is only the fifth stream in New York state where rock snot has been found. The others include the Battenkill in Washington County, where rock snot was first found in 2007, and the Esopus Creek in the Catskills, both known as top class fly fishing streams.
It has probably been spread from stream to stream by fishermen, state officials believe.
“It’s in some of the best trout streams in the state,” said DEC spokesman David Winchell.
Rock snot was known in the West, but was unknown in the northeastern United States until its discovery in the Connecticut River in Vermont in 2007.
A Skidmore College biology class, led by environmental studies professor Cathy Gibson, found the Kayaderosseras rock snot bloom at a fishing access spot along Creek Road in Milton, and reported it to DEC on Monday.
“She did report that the rocks were well covered, and chunks of didymo were sloughing off the rocks,” Winchell said.
A DEC stream biomonitoring team on Tuesday checked four spots in the area, finding didymo covering 80 to 90 percent of the Kayaderosseras stream bottom in two areas near the original find, but it also found spots both above and below the fishing access point that were uncontaminated.
“Due to the locations at the fishing access sites it is likely that it was introduced by anglers,” Winchell said.
Over time, he said, the bloom is likely to spread downstream.
DEC now hopes that anglers won’t spread if farther.
easy to spread
Winchell said the microscopic algae cling unseen to waders, boots, boats, paddles, clothing and fishing gear, and remain viable for several weeks under even slightly moist conditions. Absorbent items like felt-soled waders and wading boots commonly used by stream anglers are also thought to harbor didymo.
The Kayaderosseras is a well-known regional trout stream. It has a number of state-sanctioned fishing spots, and the state stocks trout in it each spring. It flows into Saratoga Lake after a 35-mile run through Greenfield, Milton, Saratoga Springs and Malta.
Didymo gets the name rock snot from its appearance. Cells can produce large amounts of stalk material that form thick mats on the stream bottom. The appearance of the mats has been compared to brown shag carpet, fiberglass insulation or tissue paper, state officials said. It resembles rotting cardboard when exposed and dried.
While didymo does not pose a threat to human health, DEC said it can alter stream conditions, choking out many of the organisms that live on the stream bottom — and potentially causing a ripple effect up the food chain that could affect trout and other fish.
Winchell said there’s no method for removing or destroying it once it is in a stream.
“We’ll see the worst bloom this summer, then it will settle down, based on past experience,” he said.