Invasive 'rock snot' algae found in Pennsylvania creek

(Greensburg) Tribune-Review (TNS)

Quemahoning Creek in Somerset County has a “rock snot” problem.

The invasive algae didymo, also known as “rock snot,” was recently discovered in the creek, the Pennsylvania Fish and Boat Commission announced Friday.

Somerset Conservation District employees found the algae about two months ago in a section of stream used as a trout fishery, according to conservation district manager Len Lichvar. The district turned the sample over to the fish and boat commission, which had it tested and confirmed it was didymo.

The algae can smother existing aquatic life, Lichvar said.

“It can be extremely harmful, especially to a fishery,” he said. “What impact it will have in the long term … we’ve only recently discovered it, so we can’t say for sure.”

Staff at the Quemahoning Reservoir this week found unusual amounts of algae while cleaning the screens on the reservoir gates, Lichvar said. Samples of this discovery have not been tested yet, but they look like didymo.

Lichvar suspects the algae was first introduced to the reservoir, then spread downstream into the rest of the creek. The reservoir is a popular fishing and boating spot, made even more popular during the coronavirus pandemic, which has left many people looking for outdoor activities.

“It’s been overwhelmed by users due to covid-19,” Lichvar said.

Didymo is native to Europe and Asia, but has been found in American waters for at least 100 years, according to the fish and boat commission. It’s extremely hardy, clinging to boats, waders and fishing equipment to travel from one body of water to the next.

A single didymo cell can start a whole new colony, according to the commission.

Once didymo has entered a waterway it’s almost impossible to eliminate, but there are ways to slow the spread, according to the commission.

There are a few ways to kill didymo cells. Letting equipment dry for more than 48 hours, soaking equipment in dishwashing detergent and hot water for 20 minutes, freezing equipment for 24 hours, and running boats through a hot-water car wash are all effective, according to the commission.

“We may not be able to eliminate didymo from infected waterways, but there are things we can do to slow or prevent its spread to other waters,” Heather Smiles, chief of the commission’s Division of Environmental Services, said in a statement.

Since 2007, didymo has been detected in the Delaware River, Dyberry Creek in Wayne County, the Youghiogheny River watershed in Fayette County and Pine Creek in Lycoming County, according to the commission.

Quemahoning Creek and the reservoir have become increasingly popular recreation destinations over the last 20 years, Lichvar said.

“The last thing we need is any type of impairment to slow that great progress down, unfortunately we now seem to have some,” he said. “The real fear is that it could spread further yet.”