ADVISORY posted by the Virginia Department of Health – Out of an abundance of caution, an advisory has been issued for the North Fork Shenandoah River due to the detection of cyanobacteria toxins within mat material at two sites; Bethel Road (near the intersection of Rt. 644) and at Strasburg, near S Holliday Street (Rt. 648). While the cyanobacteria mats at those two discreet locations are wide-spread, they were not observed throughout the entire ~5 mile stretch of this river segment. Weather and other environmental factors can cause rapid changes in water quality and cause mat material to shift in location. People and pets should avoid contact and accidental ingestion of cyanobacteria mats throughout the river. The drinking water plant at Strasburg is working with state and county officials to ensure the continued safety of drinking water and will continue to monitor for algal toxins at the plant intake.
https://www.vdh.virginia.gov/content/uploads/sites/178/2021/07/NF-Shenanodah-HAB-Status-Report-7.23.21_final.pdf