Why is the Beach Green?

By Wayne Cascio, MD and Elizabeth Hilborn, DVM

On July 28th a headline in The Salt Lake Tribune announced welcome news to Utah Lake’s neighboring communities and recreational visitors: “Utah Lake reopens as algal threat subsides.”  Algal threat? How can those little green cells called algae we grew in high school biology class be threatening?  ‘Algae’ is actually a term for a broad group of different kinds of microscopic organisms that can live in the water; many produce their own energy by photosynthesis. Algae play a key role in supporting the food chain and they are present in most marine and fresh surface waters.  So, how can a good thing like algae be a hazard?  Simply put, too much of a good thing can be a bad thing.

Harmful algal bloom in shore of lake

An algal bloom turned this lake green. Photo Credit: Diana L.

When growing conditions are just right, algae can form massive blooms, fouling surface water, depleting oxygen, and out-competing other organisms in the water.  The blue-green algae, or cyanobacteria, that fouled Utah Lake can produce toxins that if present in high enough concentrations can cause adverse health effects among people and animals.  Toxic blue-green algal blooms have impacted drinking water and recreational beaches, so they are a concern for officials who are tasked with protecting public health. Algal blooms can also have adverse economic impacts on communities by increasing the cost of drinking water treatment, and by affecting home prices, tourism, and industries that depend on clean water.

Nutrient pollution is a key driver of blue-green algae blooms. The nutrients come from fertilizer use and animal manure, nitrogen oxides produced by fossil fuel emissions, soil erosion, storm water runoff, leaking septic tanks, waste water, and some industrial sources.  When combined with nutrient pollution, other environmental conditions that support blooms include drought, increased water temperature and low lake and river levels. These environmental conditions may increase in frequency as a result of our changing climate.

While scientists have learned a great deal about harmful algal blooms, there is still much more that we need to learn to help communities protect themselves from the harmful effects of these blooms.  EPA is conducting research to better understand the reasons why these blooms occur, to better predict when and where they might occur, and to define environmentally acceptable levels of nutrients, algal cells, and toxins that are protective of the health of people and the environment.

EPA researchers will continue to do the science needed to understand the health and environmental hazards of algal blooms and to work with other agencies and local officials to better predict when and where blooms will occur.  Yet the best solution is to limit the occurrence of algal blooms. We can protect our water by limiting fertilizer applications, by managing storm and waste water runoff, and by preserving our land’s health and fertility by preventing soil erosion. If we are careful stewards of our land and water, we can continue to enjoy bountiful harvests from our fertile soils and also maintain safe drinking water, healthy fisheries, and inviting recreational waters.  Individuals and communities can play a role in monitoring waterways for algal blooms, and also be aware of the sources of fertilizers, waste, and nutrients that may flow into their local waters.

For more information:

Harmful Algal Blooms – https://www.epa.gov/nutrientpollution/harmful-algal-blooms

CyanoHABs – https://www.epa.gov/nutrient-policy-data/cyanohabs

States with Freshwater HABs Monitoring Programs – https://www.epa.gov/nutrient-policy-data/states-freshwater-habs-monitoring-programs

Harmful Algal Blooms: Tiny plants with a toxic punch- http://oceanservice.noaa.gov/hazards/hab/

Harmful Algal Blooms Observing System – http://habsos.noaa.gov

Harmful Algal Bloom Operational Forecast System – https://tidesandcurrents.noaa.gov/hab/

Research References:

Brooks BW, Lazorchak JM, Howard MD, Johnson MV, Morton SL, Perkins DA, Reavie ED, Scott GI, Smith SA, Steevens JA. Are harmful algal blooms becoming the greatest inland water quality threat to public health and aquatic ecosystems? Environ Toxicol Chem. 2016 Jan;35(1):6-13.

Hilborn ED, Beasley VR. One health and cyanobacteria in freshwater systems: animal illnesses and deaths are sentinel events for human health risks. Toxins (Basel). 2015 Apr 20;7(4):1374-95.

About the authors: Wayne Cascio, MD, FACC is the Director of the Environmental Public Health Division in the  National Health and Environmental Effects Research Laboratory, Office of Research and Development at the US EPA.  Dr. Cascio leads research to better understand the relationship between human health and wellbeing and the environment.

Elizabeth Hilborn, RN, DVM, MPH, DACVPM, is an epidemiology researcher in the Environmental Public Health Division, NHEERL, ORD and an internationally recognized researcher in the field of harmful algal blooms.


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