How long has the How long has the Didymo been in the US?

Answer 1

Didymo, commonly known as "rock snot," was first identified in the U.S. in the early 2000s, with reports of its presence in the Northeast occurring around 2007. It is believed to have been introduced from Europe, where it had been documented earlier. Since then, Didymo has spread to various freshwater systems across the country, causing ecological concerns due to its impact on aquatic habitats.