Maryland DNR Bans Felt Soles to Prevent Spread of Didymo

Didymo is a common name for Didymosphenia geminata, a freshwater diatom species that can form extensive mats on stream beds. The thick mats can smother native algae and aquatic insects, and make fishing very difficult.

     Annapolis, MD -- The Maryland Department of Natural Resources (DNR) is banning felt soles in Maryland waters beginning March 22 to protect and preserve native wildlife and habitats.
     “Felt is porous and can remain damp for weeks, keeping harmful microscopic organisms alive and making it virtually impossible to disinfect,” said Jonathan McKnight, head of DNR’s invasive species team. “After reviewing the science, and spending a year on outreach, public meetings and citizen response, we concluded that the only responsible action was to ban this material to halt the spread of harmful invasive organisms. The ‘do nothing’ response just would not cut it when the health and beauty of our rivers is at stake.”
     The prime culprit in this call to action is didymo, an invasive alga known to anglers as rock snot, which thrives in cold flowing waters such as trout streams. Once didymo takes hold, it can bloom into infestations of enormous numbers resulting in a yellow-brown mass that may dominate sections of a river. Over time, dramatic changes in stream biology are probable, and the thick mats of algae make fishing virtually impossible.
     New rubber soled materials offering excellent traction are readily available from various manufacturers at most outdoor retailers. DNR field biologists have had great success using the new rubber-soled boots.
     DNR biologists found didymo in Gunpowder Falls in 2008 and responded with educational efforts, adding wader wash stations at popular access points on the river. In 2011, a rock snot bloom turned up in the Savage River. Didymo is not a human health risk, but the dense mats of algae may negatively impact bottom dwellers such as crayfish, mayflies and stoneflies.
     Anglers have the most vital role to play in protecting the rivers they treasure by knowing that felt is not the only method for transporting harmful species. DNR strongly encourages all anglers and stream lovers to remove all debris and water from their boats, clothes and gear before leaving a stream. All anglers should take advantage of the wader wash stations to clean their boots and gear in the saltwater solution provided by DNR before heading to another body of water.
     In enforcing this new regulation, Natural Resources Police (NRP) understand that, in spite of extensive outreach and educational efforts, some anglers will be unaware of the new felt sole ban. Therefore, NRP officers intend initially to issue a warning and an information card to anyone wearing felt-soled boots or waders.
     For additional information on didymo, the felt ban and how to resole your boots/waders with the new rubber compounds, please visit http://www.dnr.state.md.us/fisheries/pdfs/felt_sole_faq.pdf.