Over the month of October, bright green patches of algae have appeared on the Potomac River. As the color suggests, algae are microscopic plants, which can multiply to form the floating green layers you see on rivers, ponds, and other waterways in the summer. Algae are natural members of aquatic ecosystems; they are the foundation of food chains and photosynthesize the same way as plants on land. However, algal blooms, which are an unusually high population of algae, are harmful to aquatic ecosystems.
Algal blooms appear when conditions are just right: in late summer, when the days are long and water temperatures are at their warmest, algae use nutrients dissolved in the water to multiply. Water naturally contains nutrients; however, as human populations around waterways grow, so does the amount of lawn fertilizer, pet waste, and bare soil that enter our streams, and algae use these additional nutrients to grow more quickly.
These blankets of algae block sunlight from reaching deeper areas of the water, which lowers the growth of native underwater grasses. When the algae dies and decays, this process uses up the oxygen in the water, creating 'dead zones,' where there is too little oxygen for fish and other aquatic life to survive. Because algae grow and die quickly, these dead zones persist and become larger and larger. Some types of algae can produce toxins that are harmful to people and animals, resulting in beach closures or reduceddrinking water supplies when water intakes are shut down to keep the toxic algae out of drinking water. Locally, dead zones are an annual occurrence in the Chesapeake Bay. In fact, in a 2015 study, the University of Maryland Center for Environmental Science found that algal blooms in the Chesapeake Bay have lasted longer and occurred more frequently over the last 20 years.
Nitrogen and phosphorus, the two leading nutrients that fuel algal blooms, come from a variety of sources: stormwater runoff, sewage treatment plants, and air pollution. These two pollutants, along with excess sediment, are recognized by the EPA as major players in the overall health of the Chesapeake Bay. Through a permitting system administered by states in the Bay's watershed and the District of Columbia, the EPA has set limits on how much of these pollutants can enter the Bay through storm drain systems. Permit holders, including JBM-HH, are required to take action to reduce the amount of these pollutants and meet these limits.
While the biggest contributors of nitrogen and phosphorus are industrial sources, JBM-HH residents, employees and visitors can take action to help keep nutrients from reaching the Chesapeake Bay:
• Apply fertilizer to lawns and gardens based on manufacturer's instructions--don't over fertilize.
• Choose a period of dry weather to apply fertilizer. Rain dissolves fertilizer and carries it into storm drains.
• Always pick up pet waste. Pet waste is rich in nutrients, as well as bacteria.
• Plant over bare spots in your yard. Planted areas slow down runoff and help rain water soak into the soil, which keeps polluted runoff from making it to our waterways.
To report conditions that could cause stormwater pollution or to get more involved with stormwater activities at JBM-HH, call the Environmental Management Division at 703-696-8055.
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