RD411 - Harmful Algae Blooms in Virginia – September 2021
Item 377 P. in Chapter 552 of the 2021 Special Session I Acts of Assembly directed the Virginia Department of Environmental Quality (DEQ) to convene a workgroup, in conjunction with the Virginia Department of Health (VDH) and the Virginia Department of Agriculture and Consumer Services (VDACS), to conduct research and complete a single collaborative report that provides findings and recommendations related to:
(i) the location, frequency, and severity of harmful algae blooms in Virginia waters;
This item directed the workgroup to provide its findings to the Chairs of the House Agriculture, Chesapeake and Natural Resources Committee and Senate Agriculture, Conservation and Natural Resources Committee no later than September 1, 2021.
Algal blooms are natural occurrences. Human activities, including housing developments, agriculture, silviculture, road construction, etc., can increase the frequency, size, and duration of the bloom. There are many different kinds of algae, and accordingly, blooms are different and only some are considered harmful. For the purposes of this report, Harmful Algal Blooms (HABs) are a subset of algae and cyanobacteria that produce toxins that may adversely affect human health through ingestion of HAB-impacted water or shellfish. As required by Item 377 P., this report summarizes existing knowledge and provides recommendations for potential further actions related to three main topics: 1) the location, frequency, and severity of HABs in Virginia, 2) the factors that lead to HABs, and 3) plans for state agencies to lead or support mitigation of HABs. These three topics are addressed within the context of the above working definition.
The reporting and identification of potential HABs in Virginia’s marine and freshwaters has increased in recent years in part because the criteria for characterizing HABs has changed. VDH and DEQ, along with academic partners, have investigated complaints of potential HAB events all over the state. While HAB events in Virginia have not yet been severe, the magnitude, frequency, and duration of cyanobacteria blooms above new VDH thresholds has led to a growing number of recreational swimming advisories across the state in recent years.
For example, in July and August 2021, DEQ investigated multiple reports of potential HABs that were submitted through the Harmful Algal Bloom Portal. Subsequent laboratory analysis indicated that algal toxins (including microcystin, cylindrospermopsin, anatoxin-a, and saxitoxin) were present within algal mats in multiple locations along the North Fork Shenandoah River. At some of those sites, toxins and potentially harmful algal cells were also detected in the water, although at the time of writing this report, all concentrations were at low levels and well below VDH advisory thresholds for recreational use. However, due to the presence of cyanobacteria in algal mats detected at sites along the river, VDH issued and subsequently extended a recreational advisory for the North Fork Shenandoah River to ensure the public was aware of the presence of these algal mats and to ensure that people, in addition to their pets and livestock, could take caution to avoid contact with visible algal mats and scum. The advisory covered approximately 52.5 miles of the North Fork Shenandoah River as of August 10, 2021.
As an illustration of other effects HABs or potential HABs may create, the Town of Strasburg and the City of Winchester adjusted their raw-water intake treatment protocols and increased monitoring since the bloom was discovered. The Town of Woodstock increased monitoring, and made plans to adjust their raw-water intake treatment protocols if necessary. As of the time this report was drafted, drinking water in the Town of Woodstock, the Town of Strasburg, and the City of Winchester was safe to use and drink, according to public statements by the localities. The three localities planned to continue active monitoring of drinking water, and to notify the public if any protective action became necessary.
An online report was created to reflect the HAB advisory status of the North Fork Shenandoah River and may be found at “North Fork of Shenandoah River Status Report (8.10.21)".
The challenges surrounding the increase in HAB events is two-fold. First, HAB events pose a challenge and potential financial burden for stakeholders, businesses, and citizens who rely on Virginia’s waterways for recreation, vacation rentals, fishing charters, seafood production, and other water-tourism related activities. Second, Virginia’s agencies responsible for responding to HAB events lack resources to keep up with the demand. VDH and DEQ do not currently have the funding necessary to adequately support the existing marine HAB monitoring and response program which conducts surveillance year round to protect the public and the shellfish resource on the coast of Virginia. DEQ maintains a robust monitoring network, but has no budget or staff resources to perform the additional monitoring needed to support a consistent schedule of freshwater HAB response monitoring necessary to determine causal factors and protect human health. VDH does not receive any funding to support the 100,000 miles of freshwater rivers and streams and 248 publicly owned lakes, all designated to support recreational uses throughout the state. Given the scope and complexity of HAB occurrences in Virginia, the timeline associated with this report was not sufficient to determine exact causal factors contributing to specific HAB events.
Plans and strategies for appropriate mitigation efforts include local waterbody cleanup plans for impaired waters, and the implementation of the Chesapeake Bay Watershed Implementation Plan. These strategies typically require rigorous data collection and analysis as well as significant funding for the installation of Best Management Practices and additional wastewater treatment technologies. Some of the most common in-situ treatment strategies are also reviewed in this report. This is an expanding field of study and the range of treatment strategies is broad and increasing. In addition, an analysis of the relative cost of each strategy is beyond the scope of this review, as such an analysis requires extensive information on the systems and algae types to be treated, and DEQ would need additional contractual support to perform the analysis.