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VDH Issues Algae Mat Alert for Strasburg- North Fork Shenandoah River

On 07/29/22 Virginia Department of Health(VDH) issued a Algal Mat Alert near Deer Rapids bridge, North Fork Shenandoah River and 2.5 miles above and below site. On 8/5/22, VDH expanded this area to include an 11.5 mile stretch up to the confluence of Cedar Creek with the North Fork, west of Strasburg. Potentially harmful algal cyanobacteria mats were observed and identified as extensive and unavoidable for this area. Algal mats (along the shoreline, along the bottom, or on the surface) have the potential to release toxins when disturbed. Be extra careful to avoid, and to keep children, livestock, and pets away from any mats along the shoreline. These mats, as they start to break down, are more likely to be releasing toxins.

Click here to view VDH’s latest alerts and recommendations on their Algal Bloom Surveillance Map

What is an Algal Mat Alert?

VDH issues an Algal Mat Alert when investigations at a site indicate cyanobacteria mats are extensive and potentially unavoidable. Water column sampling is conducted upon the issuance of an alert. If an area is under an alert, these samples are either pending results, or indicate cyanobacteria and cyanotoxins in the water column are at safe swimming levels. Recreational water uses may continue as long as contact with algal mats, which may have the potential to produce toxins, can be avoided. VDH will issue a recreational advisory if water column samples are found to contain unsafe levels of cyanobacteria or toxins for swimming. Be sure to steer clear of, and keep children, pets, and livestock away from algal mats. This material, when disturbed or breaking down, has the potential to release toxins that can cause skin reactions upon contact, and if ingested, severe sickness or death in pets and livestock.

If you see an area with extensive algal matting, please report it to VDH here.

Citizen reports are the basis for initial and follow-up water column testing and the issuance of Algal Mat Alerts and Recreational Advisories.

Help FNFSR keep VDH and other conservation partners in the loop as the algae season progresses by submitting weekly photos of your home stretch of the river to FNFSR’s Algae Watch map is used to give VDH a chronological view of the progression of blooms, and lets them know when they may want to reassess an alert or advisory. Click here to learn more about how you can get involved, and check out our 2021 and 2022 maps.

Read Friends of the North Fork’s general Safety Guidelines for recreation in the North Fork here.

See the Virginia Department of Health’s page on harmful algal blooms with a clarification between healthy and harmful algal blooms.

Report to VDH any algal blooms that you deem to be harmful here.