Concentration of CO2 in the Atmosphere

Beating Blue-Green Algae

A blue-green algae at Clear Lake, California, resulted in oxygen depletion in the water and the subsequent mortality of multiple aquatic species, including carp, catfish, bluegill and crappie. (Kirsten Macintyre/Flickr)

Jessie Haas

Nothing ruins a summer day like getting to the beach and discovering it’s closed due to a blue-green algae bloom. Or having your dog get sick from it.. Or getting sick yourself.

Blue-green algae, a form of cyanobacteria, is natural and ancient. It blooms under conditions of excess nutrients in still, warm bodies of water, and then dies as rapidly as it came. However, the death process consumes large amounts of oxygen, harming or killing aquatic life. Some species also release toxins which may linger after the bloom is apparently over. These are harmful, sometimes lethal, for humans and animals, with dogs and children being most vulnerable. Many dogs die every summer from swimming in contaminated water. Some species of blue-green algae are also associated with major, long-term illnesses like Lou Gehrig’s disease. Not all types of blue-green algae are toxic, but it’s difficult to know what you’re looking at if you’re not an expert.

There is an ongoing interstate and international effort to reduce algae blooms in Lakes Champlain and Memphremagog, which focuses heavily on farming and the built environment. But homes in the Champlain Basin, with their surrounding lawns, also make an impact on bodies of water. We can all play a role in reducing the excess nutrients being washed into our ponds, lakes, rivers, and ultimately Long Island Sound, by modifying what we do in our watershed.

Many solutions focus on lawns, and it’s time to face facts. That close-clipped patch of greensward is a biological desert, which displaces native species that once thrived there. Not only that; the care we lavish on that grass, including mowing, fertilizing, and pesticides, makes the lawn an active threat to the natural world around it, particularly bodies of water. (Golf courses, we’re also looking at you!) Lawn turf has short roots, which do not absorb and sink water very well. That makes your lawn more like an impervious surface than like a natural meadow; everything you put on it will wash right off again during a heavy rain, straight into the nearest stream, lake, or pond.

There’s a lot we can do to change that, and refreshingly, it involves doing less work, not more. Make that lawn a lot smaller. Rewild the margins, especially near ponds and streams. Riparian buffers aren’t just for farms! Allow native perennials and shrubs to grow near the water’s edge, or choose and plant them according to your taste. These deep-rooted plants will divert and sink run-off from your property into the ground, while feeding bugs, birds, and maybe you, depending what you choose to grow. If you think the neighbors will complain (people do tend to be “judgey”!) put up a little sign saying “This is an ark,” or “Lake Protection Zone,” or whatever tickles your fancy. Golf courses, which will have difficulty with some suggested practices, might be able to install wild buffers.

Fertilize less, or not at all. Grass usually does just fine without it. If yours doesn’t, that’s a sign that it’s truly out of its comfort zone. Take the opportunity to reseed with something that needs less care. Dutch white clover is pretty, feeds pollinators, gathers free nitrogen out of the air, and never gets tall.

Mow less often. No Mow May is a movement asking homeowners to skip mowing their lawns through the month of May, to allow pollinators to feed. When you stop mowing, you will find new plants emerging from the seedbank, deeper-rooted perennials like ajuga, violets, dandelions (gasp!) and others you may have previously considered to be weeds. Enjoy them, watch who feeds on them, and consider making them a permanent part of your landscape. A plusher look on the surface is a sign of deeper roots underground, which sink and absorb water and nutrients. You can also let the grass grow tall, and mow walking paths through it.

Plant trees – native trees. They absorb significant amounts of water from rain and snow melt, and provide cooling through their shade and transpiration. That’s a benefit to both you and any nearby body of water, as algae blooms are triggered by excess heat.

Rain barrels catch and divert the flow of water from your roof. Use the captured water in your garden. Or guide it, and the runoff from your driveway, into a rain garden, an attractive patch of native plants designed to catch and sink excess water from heavy rains. Rain gardens also attract frogs, salamanders, pollinating insects, and birds.

If you have a pond on your property, you can prevent algae blooms by installing an aerator or fountain. But along with that, look at first causes. How is that extra fertility getting into the water? Identify the sources, and buffer them. If you have vegetation near the bank of the pond, mow and rake in the fall, so the excess nutrients don’t end up in the water next spring. Put the clippings on your compost pile, or chip them to mulch other plants. Similarly, clean up pet droppings and dispose of them, and don’t let livestock graze the banks of a body of water, except in the fall as an alternative to mowing.

Speaking of excess nutrients, if you live near a body of water, it’s important to make sure your septic system is in good working order. You don’t want your leach field leaching into a stream or lake.

Everything you do to help keep the water free from algae blooms will beautify your property, increase the life there, and help cool your particular part of our fevered planet. There’s literally no downside.

Links provided in the online posting of this article at

Jessie Haas lives in a 450 square foot off-grid cabin with husband Michael J. Daley. She is the author of over 40 books, including The Hungry Place.

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