Windsor Lake Closes Due to Harmful Algae Blooms

With all the sunshine Colorado generally sees, when you add heat, you have the recipe for potential harmful algae blooms. The Town of Windsor closed Windsor Lake because of such algae on July 7, 2026.

What Exactly Are 'Harmful Algae Blooms?'

From the Town of Windsor:

Harmful algae blooms—also known as cyanobacteria—are becoming increasingly common in lakes throughout Colorado.

The algae multiply rapidly and are aided by a combination of unusually sustained hot weather, stagnant water and stormwater runoff that includes nutrient pollution from fertilizers.

What Does the Closure of Windsor Lake Include?

The Town of Windsor has closed the lake to recreation such as swimming, tubing and water skiing. Non-motorized boaters can use their permits at their own risk, though staying out of the water is highly recommended.

READ MORE: G.O.A.T. Sports Bar Opens Windsor Location

What Dangers Are Associated with Harmful Algae Blooms?

While it all depends on which toxins are in the algae, humans exposed could feel stomach pain, develop a rash, sore throat, and more. More serious symptoms can include liver damage and seizures. Animals/pets are very susceptible to being affected.

What About the High-Tech Devices Windsor Bought to Help with the Algae Blooms?

It was in May of 2024, that Windsor spent $250,000 on ultrasonic buoys to help keep the algae from growing, by depriving the algae of the nutrients they need to grow.

From Windsor's Deputy Town Manager:

We’re following our protocols by closing the lake upon a positive test, but the buoys are doing their job. We’re seeing really good improvement, but it takes a little time. Until then, we want to be extra cautious and keep everyone out of the lake until it’s fully safe again.