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In the summer of 2021, The Virginia Department of Health (VDH) issued a Harmful Algae Bloom Advisory for recreational activity in the North Fork that, by August, included a 52.5 mile stretch of the North Fork of the Shenandoah from Chapman’s Landing, near Willow Grove, to Riverton, near Front Royal. Click here to read VDH’s 8/10/21 Advisory

This harmful algae bloom advisory for the North Fork of the Shenandoah was lifted on September 17,2021.  While algal mats have dissipated and cyanobacteria cells were not being detected at that time, algae concentrations can change with favorable conditions. Please stay alert and avoid any discolored water, scums, or algae mat material whenever you are out recreating on the river.  Click here to read the VDH press release lifting the harmful algae bloom advisory.

If you see an algal mat, do not enter the river and keep your pets away.  Not all mats are toxic, but when in doubt, stay out!

As we enter another summer, you can help Friends keep an eye on this problem by emailing us a photo of the river around where you live or like to recreate to  We are also looking for a few people to document local sites weekly to track the progression of blooms.   Please include the location of your photo and any other observations you have, i.e. wildlife, fish, odor, litter, river flow, etc.  If you are able to send a weekly photograph to monitor your spot until the fall, please let us know in your email. 

Check out the map below for photos collected from around the North Fork in the summer of 2021.  

We share a digest of these collected reports with VDH, DEQ, and the Shenandoah Riverkeeper to aid in their efforts to test for harmful algae, keep the public informed, and combat the source of algal blooms. Friends will not share your name or any personal information in connection with any photos you submit, unless you note that you would like to be credited.