by Diane L. Mas, PhD, REHS/RS, Associate | Business Line Manager
EPA Releases Guidance for Swimming Advisories and Recreational Water Quality Criteria
Last summer, harmful algal blooms (HABs) in Florida captured the attention of the nation. The sight and smell of these blooms was unmistakable and unpleasant, forcing people not only out of the water, but into their homes to avoid them. While the HABs in Florida received substantial media coverage and were even a topic in the Florida governor’s election, the problem of HABs exists nationwide, including here in the Northeast. As summertime warm weather, sunshine, and still waters set up the conditions for algal blooms, the U.S. Environmental Protection Agency (EPA) has released guidance to protect swimmers from two of the most common toxins produced by HABs.
HABs are caused when cyanobacteria, also known as blue-green algae, multiply rapidly. HABs can occur in both fresh and marine waters. Conditions that favor the growth of cyanobacteria and the formation of HABs are elevated levels of nutrients, such as phosphorus and nitrogen, along with warmer water temperatures, abundant sunlight, and calm waters. Some cyanobacteria produce toxins, called cyanotoxins, that are harmful to people and animals. In May 2019, EPA release guidance on allowable levels of two of those toxins – microcystin and cylindrospermopsin (see box). These toxins can produce a variety of health impacts, depending on the magnitude and type of exposure, that range from skin irritation to neurological effects.
The guidance released is also intended to help states and tribes that are responsible for setting ambient water quality standards and determining when use of a water body is impaired. EPA recommends that states use a 10-day rolling assessment period and when a toxin concentration is higher than the recommended concentration, then that event should be considered an “excursion” from the recreational criteria for safe water quality. When more than three excursions occur within a recreational season and that pattern reoccurs in more than one year, it is an indication the water quality has been or is becoming degraded.
Protecting Swimmers from HABs Is a Two-part Approach
First, you should know how to identify and avoid HABs; you can’t tell if the cyanotoxins are there simply by looking at a HAB, so avoidance is the best action. Remember – if in doubt, stay out. And if you think you or your pet has come in contact with cyanobacteria, shower or wash off immediately. For nearly a decade, Fuss & O’Neill has been monitoring water for cyanobacteria bacteria and cyanotoxins and helping train watershed and lake managers and public health professionals to identify HABs and understand and educate the public about their risks.Second, there are things that can be done to limit the formation of HABs. While cyanobacteria will almost always be present in recreational waters in some concentrations, it is excess nutrients, especially phosphorus in freshwaters, that “feed” the blooms. Watershed, stormwater, and wastewater management are all important actions to keep HABs from forming and to limit the duration and extent of HABs when they do occur. Fundamentally, this means assessing where nutrients are coming from and how to keep them out of the water and unavailable to cyanobacteria. This is a core focus of our Water Resources practice at Fuss & O’Neill and we work with states, communities, watershed groups, and lake associations to identify, quantify, and limit nutrient pollution to inland and coastal waters.
For more information on HABs, monitoring water quality for cyanotoxins and nutrients, and how to address the nutrient pollution that encourages HAB formation, contact Diane Mas at email@example.com or 800-286-2469 x4406.
About the Author:
Diane is an environmental engineer in the Water and Natural Resources Business Line at Fuss & O’Neill, Inc. and a founding member of the company’s environmental impact assessment practice. She has spent nearly 20 years working in the areas of water quality modeling, watershed management, and environmental impact assessment. Her current areas of water resources practice focus on climate change resiliency and adaptation for water resources; water quality assessment, modeling, and watershed management; harmful algal bloom impacts to drinking and recreational waters; and the relationship between water quality and public health. She also leads the preparation of state and federal environmental impact assessments, continuing to look for ways to streamline and focus analysis on key issues to assess and mitigate potential environmental effects.