Algal Outbreaks In the Shenandoah

Photo by Tusik Only

algaeinhandThe Shenandoah River has been plagued by excessive algae outbreaks for some time now. This was brought to light in 2005 when a large-scale fish kill triggered an investigation by Virginia’s Fish Kill Task Force into the underlying issues. The Task Force discovered that pollution from large agricultural operations was creating a whole host of issues, such as intersex fish and fish afflicted with infections, lesions and heavy parasite loads. In addition to the physiological effects on the fish, the excess nutrients in the river were leading to uncontrolled algal growth.

Since these studies were done, more fish kills have been reported in the Shenandoah and excessive algae growth remains prevalent. These algal outbreaks are detrimental to aquatic life as well as recreation on the river such as fishing, paddling, tubing, and swimming. Despite extensive data demonstrating that widespread algae outbreaks prevent the river from meeting Virginia’s water quality standards, the Virginia Department of Environmental Quality has refused to list the river as impaired. Listing a waterway as “impaired” triggers a regulatory process leading to the imposition of limits on the amount of the pollution causing the impairment into the waterway. In this case, Virginia would be required to develop limits on the total amount of nitrogen and phosphorus being discharged into the Shenandoah that are protective enough to prevent algae outbreaks and improve water quality. The main source of these discharges is from agricultural runoff of poultry litter and cattle manure from already saturated fields..

cattle in riverIt is obvious that excessive algal growth is impairing the overall health of the Shenandoah River and the public’s ability to enjoy it. Not only that, but it is reducing the biodiversity in the river as many types of fish and benthic creatures need good subaquatic vegetation in order to survive. We are also witnessing the slow but steady rise of nitrates in groundwater, from which over half the population of the Shenandoah Valley draws its drinking water. The underlying causes need to be addressed, and that is one of the purposes of the Respect the Shenandoah Campaign. To reduce harmful algal outbreaks, we will advocate for limits on the amount of cattle manure and poultry litter that can be applied to farm fields and for stream fencing to keep cattle from defecating in the river.

You can help by downloading the mobile app Water Reporter and reporting algal outbreaks when you see them. Every bit of documentation helps!

You can also submit complaints about algae outbreaks directly to Virginia’s Department of Environmental Quality.


Respect the Shenandoah - Shenandoah RiverkeeperThe Respect the Shenandoah Campaign is built on the recognition that we are all responsible for protecting our rivers so that others may use and enjoy them. We all use and enjoy the river. Working together, we can all Respect the Shenandoah and protect it as well.