News Release

Blue-green algae blooms have been identified on at least two shores of Shell Lake.

Blooms were discovered on the north and west shores of Shell Lake during the afternoon of Thursday, September 10, 2020. Additional blooms may be present on other parts of the lake.

You should avoid entering the water and keep dogs out of the water anywhere blue-green algae is present. It is important for pet owners to prevent their dogs from ingesting the mats via drinking the lake water, eating any of the material that may be washed up on shore, or licking it from their fur after swimming. Blue-green algae can move to different locations in the lake and can occur in any lake. Be sure to always check the water before swimming or letting dogs enter it.

What are blue-green algae?

  • Blue-green algae are photosynthetic bacteria known as cyanobacteria and are a natural part of water bodies. With enough sunlight and nutrients, cyanobacteria can grow to high levels and form a blue-green algae bloom.
  • Blooms are often smelly, look like spilled paint or pea soup, and can change the color of the water to green, blue, turquoise, purple, tan, or white. Some blooms form a layer of scum or mats on the surface of the water.
  • While some blooms can stay in the same location for a long time, others can quickly come and go with changing currents and wind patterns.
  • Blue-green algae blooms can produce toxins that can make people and animals sick after they swallow, breathe in, or have contact with the water.

How can I keep myself, my family, and my pets safe at the lake?

  • When searching for a spot to swim, choose the clearest water possible. Avoid water that looks like spilled latex paint, looks like green pea soup, is discolored or streaky, has small green dots floating in it, has floating scum, globs, or mats, or has dead fish or other animals.
  • Always shower off after swimming in lakes, rivers, and ponds.
  • If dogs swim in scummy water, rinse them off with fresh, clean water and don’t let them lick algae off their fur.
  • Don’t swim or allow your pets to swim in places where beach closure or water quality notices are posted.
  • Try not to swallow the water. Besides blue-green algae, lake, river, and pond water can contain other bacteria and parasites that can make you sick if you swallow it. Always use safe water for drinking!

[Photos by Jeremy Bloomquist, Land and Water Resources Manager, St. Croix Environmental and Natural Resources Department]


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