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Shenandoah Algae

DEQ received EPA's approval of the 2014 Integrated Water Quality Assessment Report on May 19, 2016. Action had been delayed due to citizen concerns raised about algae growth impacting recreation use in the Shenandoah River. DEQ responded by revising the Report to list 5 stream segments, totaling about 25 river miles, as having an observed effect, but with insufficient data to determine whether or not the recreation use was supported. These segments have been prioritized for follow-up monitoring this summer and fall by DEQ to test field methods that are scientifically based, defensible and reproducible, for estimating the percent coverage of river bottom by filamentous algae. Other commitments have been agreed to for future activities, including decisions on thresholds for percent coverage that constitute a 'nuisance' condition and impairment under the general narrative water quality standard, and inclusion of such thresholds in DEQ's guidance for the 2018 Assessment Report.

On March 29, 2018 DEQ hosted an informational webinar to provide a summary of the 2017 monitoring season and proposed assessment methods. Formal public comments on algae monitoring and assessment were accepted during the comment period for the 2018 Water Quality Assessment Guidance and are available along with a link to the final guidance manual. The recording of the webinar is available at the following link: The slides used in the webinar are also available.

On December 2, 2016 DEQ hosted a public information webinar to share Virginia's progress on developing filamentous algae field estimation methods. The presentation from that meeting is available, and the public notice for that webinar can be found on TownHall.

The Draft Shenandoah River Monitoring Plan is available at this link: Draft Shenandoah River Monitoring Plan

For more information, please contact Sandra Mueller at or 804-698-4324.

DEQ field staff estimating percent coverage of algae

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000

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