Toxic algae threatening waterways

Green slime. Red tide. Brown scum. Toxic algae blooms are fouling waterways across North America these days, killing fish in Florida, sickening sea lions in California, temporarily closing beaches on Canada’s beautiful Pelee Island and even shutting off tap water to 400,000 residents of Toledo, Ohio, for two days after this gunk grew too close to water-intake pipes in Lake Erie.

Those toxic algae blooms aren’t really made up of sea plants; the creatures photosynthesize like a plant, but they’re a collection of nasty bacteria and other microorganisms. Some of those microbial stews can produce one or more toxins (they don’t always) that cause you skin irritation, gastrointestinal problems and liver failure in rare cases, and kill marine life. The toxins can also harm pets and livestock. And even a non-toxic bloom can suck oxygen from the water, suffocating fish.

Algae blooms are millions of years older than you, but researchers think they’re happening more often – and sticking around longer – thanks to two factors. One is warmer water; the other, an uptick in phosphorus levels, the algal blooms’ favorite feast. The increase in their mealtime favorite is in large part due to fertilizer runoff from farms and lawns.

Scientists and lawmakers are working to rein in the problem, devoting $1.6 billion alone to a Great Lakes Restoration Initiative to help farmers control runoff and create wetland filters. A dozen states now have rules that ban, at least in part, the use of phosphorus-containing fertilizers on lawns and golf courses. Here’s what you can do, too:

  • Start by steering clear of a bloom. Follow advisories and avoid swimming in or using water from a tainted area. (Boiling, using disinfectants, even filtering at home using activated charcoal isn’t enough to always make sure water is safe during a ban). Stay away if water looks odd. Algae blooms may look like pea soup or like long green streaks, scum or mats on the water. But they also can be subtle. If water looks greenish and cloudy, and you can’t see your feet when standing knee-deep in it, get out. That’s why you should shower off with soap and water after swimming in a lake. And don’t go boating, water skiing or ride a jet ski through algal blooms. That exposure can be harmful.
  • Get smart about fertilizer. On your lawn, use a phosphorus-free fertilizer. (Look for the three numbers on the fertilizer bag that tell you how much nitrogen, phosphorus and potassium the fertilizer contains; the middle number should be zero.) It really can make a difference: In one recent University of Michigan study, phosphorus levels in a local river dropped 28 percent after the town of Ann Arbor banned phosphorus fertilizers. If you think your soil needs phosphorus, get it tested first. You’ll find test kits in garden stores and online. Repeat your test every two to three years.
  • Keep fertilizer, grass clippings and leaves out of local waterways. Gotta fertilize? Don’t spread it before a heavy rain and keep application of it at least 25 feet from ponds, streams, lakes and rivers. Sweep up extra fertilizer that lands on driveways, sidewalks or in the street. Also sweep grass and fallen leaves off sidewalks and other paved areas. Storm water from paved areas rushes into drains that often lead to streams, rivers and lakes, carrying this phosphorus-rich stuff along with it. It can end up in distant waterways and ultimately in the sea.
  • Keep a lid on pet business – and yours, too. Human and pet waste is another source of phosphorus that toxic algae love to munch. So don’t let rain and snowmelt carry it away. Pick up pet droppings. If you have a septic system, have your tank pumped out about every two years to prevent overflow. Get it inspected regularly, too. In a year, an adult’s “waste products” include about 1.2 pounds of phosphorus, enough to feed 300 pounds of algae!


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