Didymosphenia geminata

Buryatia Widespread across large areas of Russia. Occurrence, ecology, water quality, and scanning electron micrography of D. geminata from Irokinda Mine Site, Buryatia, John G. Aronson, North American Diatom Symposium, Sept, 2011.

Distribution map - Confirmed presence of Didymosphenia geminata in the United States and Canada. Source: EPA 2007[9]

Alberta: Earliest anecdotal reports of D. geminata blooms in Alberta rivers occurred as early as the mid-1990s (e.g. the upper Bow River in Banff National Park). Reports of Didymo presence and bloom formation have been documented for most rivers in the South Saskatchewan River Basin in recent years (2005 to present).

British Columbia: D. geminata was first reported as a nuisance species in the late 1980s on Vancouver Island. Since that time, outbreaks of Didymo have been reported on the island and on the mainland.[10]

Quebec: D. geminata was first officially reported in 2006[11] but a recent report demonstrates that it was present in the sediments back in the 70s at the least.[12]

New-Brunswick: D. geminata was first reported in 2007.

Ontario: D. geminata was reported in the upper St. Marys River in 2015 and 2016.[13][14]

Arkansas: In late spring / early summer of 2005, didymo was found directly below Bull Shoals Dam on the White River. The Arkansas Department of Environmental Quality has found a 13-mile reach of the river to be affected.[15]

Arizona. Found in Oak Creek just above the Pine Flat Campground in late August 2015

California: Rock snot has been around in Northern California for quite some time, and is commonly found on the North and South Fork of the Yuba River. It can also be found in reservoirs such as Lake Shasta, Bullard's Bar Reservoir, and Scotts Flat Lake.

Colorado: The range of Didymosphenia geminata was extended into Colorado by limnologist John G. Aronson, who collected it in 1976 from upper Fish Creek, near Steamboat Springs, Colorado.

Connecticut: In 2011 anglers reported blooms of didymo in the West Branch of the Farmington River to the Connecticut Department of Energy and Environmental Protection.[16]

Idaho: According to the Idaho Department of Fish and Game, didymo has been identified along the South Fork of the Boise River for a number of years. Biologists cannot say for sure if it is native to the drainage, or has appeared in the last 10 to 15 years.[17]

Indiana: Found in unnamed creek which feeds into Patoka River; Orange County. (pers. obs: amateur naturalist)

Kentucky: Didymo was found in the Cumberland River below Wolf Creek Dam in the Crocus Creek area 2008. The State of Kentucky has banned felt-soled waders in the river to prevent spread of the organism.[18]

Maryland: In May 2008, didymo was found in the Gunpowder River in Baltimore County.[19] In December 2009, it was found in the Savage River in western Maryland.[20] In May 2012, its presence was confirmed in Big Hunting Creek in Frederick County.[21]

Missouri: There are currently no known infested streams in the state. The nearest infestation is located in the White River, just south of the Missouri-Arkansas border.[22]

New Hampshire: During the summer of 2007, didymo was discovered for the first time in New Hampshire in the Connecticut River near Pittsburg.[23]

New York: Didymo is now considered likely to be native to New York.[24] In August 2007, didymo was found in New York State in a section of the Batten Kill, a Hudson River tributary, in Washington County.[25] It has also been found in Esopus Creek in the Catskills.[26] Black Creek Washington County

North Carolina: A slithery, mucous-like algae known as “rock snot” is the latest in a long line of invasive species haranguing Western North Carolina's famous trout waters. The N.C. Wildlife Resources Commission is advising anglers to use extra caution when cleaning their equipment to prevent the spread of didymo, which was recently found in the Tuckasegee River in Jackson County.[27]

Pennsylvania: Didymo has been confirmed in the Delaware River.[28] In 2012, its presence was confirmed in the Youghiogheny River.[29] In 2013, PA Department of Environmental Protection put out an alert that it has now been discovered in Pine Creek, Lycoming County.[30]

South Dakota: Didymo has been present in Rapid Creek in South Dakota since at least 2005, and is blamed for a significant decline in the brown trout population there. It is also present to lesser extents in other nearby locations.[31]

Tennessee: Didymo was found in the tailwaters of the Norris, Cherokee, Wilbur and South Holston hydroelectric dams in 2005, the first U.S. finding east of the Mississippi River.[32]

Vermont: In June 2007, didymo was discovered in the Connecticut River near Bloomfield, Vermont, its first recorded discovery in the northeastern United States. The sighting was reported by a fishing guide and confirmed by Dr. Sarah Spaulding, a didymo expert from Denver, Colorado.[33]

Virginia: Didymo was identified in western Virginia in the summer of 2006 in the Smith River, the Jackson River, and the Pound River.[34]

Seneca Creek in eastern West Virginia

West Virginia: In 2008, didymo was found in West Virginia in the Elk River in Webster County near Webster Springs and in Glady Fork and Gandy Creek, both in Randolph County.[35][36] The alga was found in Seneca Creek in Pendleton County in 2009.[37]

Chile: In 2010, the United States Geological Survey (USGS) and a Chilean laboratory, Centro de Investigacion en Ecosistemas de la Patagonia (CIEP), confirmed the identification of the diatom D. geminata (didymo) as forming extensive blooms in Chilean rivers in Chile's Los Lagos Region (X Región de Los Lagos) in the Andes west of Esquel, a town in the Chubut Province of Argentina, with reports from the Espolon River and the Futaleufú River for a total of more than 56 river kilometers affected.[38][39][40]

D. geminata was discovered in New Zealand in 2004, the first time it was found in the southern hemisphere. To restrict its spread, the whole of New Zealand's South Island was declared a controlled area in December 2005. Extensive publicity was carried out to limit the spread, but it has subsequently been found in an increasing number of rivers there.