Harmful algae: Spot it, avoid it, prevent it

Harmful algae: Spot it, avoid it, prevent it
Posted on 08/15/2019
Blue-green algae can be harmful to children and animals

It’s the time of year when vivid green plants and algae flourish in ponds. While most aquatic vegetation is a positive part of the pond ecosystem, some types of algae can be harmful to people and pets.

Algae most commonly starts to appear in our ponds and lakes during August and September, when hot, dry periods encourage its growth. There isn’t much you can do remove algae. The best course of action is to wait for rain to dilute the water and flush out the algae.

Algae blooms are unpredictable. They can develop rapidly and may move around the lake or pond, requiring visitors to exercise their best judgement.

If there is scum or paint-like surface, or if the water is bright green, avoid contact and keep pets away. These are indications that a harmful bloom – like blue-green algae – might be present. Pet owners should be aware that animals that swim in or drink water affected by a harmful algal bloom or eat dried algae along the shore may become seriously ill or die.

When a blue-green algae bloom is present, take the following precautions:

  • Do not let pet or livestock drink the water.
  • Lake or pond water, regardless of blue-green algae status, should never be consumed by humans.
  • Water contact should be avoided.
  • Fish may be eaten if they are rinsed with  clean water and only the fillet portion is consumed, while all other parts are discarded.
  • Do not allow pets to eat dried algae.
  • If algae-contaminated water contacts skin, wash with clean water as soon as possible.
  • Avoid areas of visible algae accumulation.

Preventing algae growth: You can help!

The best way to prevent harmful algae blooms is to limit the amount of excess nutrients – the main cause of algae blooms – that enter streams and ponds. The most common source of nutrients in our water is one you’re probably using at home: fertilizer.

  • Follow fertilizer instructions carefully, and use sparingly.
  • Make sure you’re using the correct fertilizer by having a soil test done to determine what nutrients your lawn really needs. Over applying fertilizers can result in harmful runoff.
  • Allow proper drying time after you’ve applied fertilizer. Never use lawn chemicals before a heavy rainfall is expected.
  • Use phosphorous-free fertilizer. Phosphorous is a significant nutrient pollutant in our water.
  • Consider mulch mowing. Leaving your grass clippings on the lawn will return up to 25 percent of the needed nitrogen.
  • Use compost or natural lawn chemical alternatives.
  • Landscape with native plants. Their natural ability to thrive in our climate and soil reduces or eliminates the need for fertilizers, watering or pesticides. 
  • Exercise caution when fertilizing on slopes and lawn edges to prevent the chemicals from washing into nearby storm sewers.

Published Aug. 15, 2019