Windsor Lake

Precautionary Health Advisory   

Out of an abundance of caution the Town of Windsor is closing Windsor Lake Reservoir to town-provided recreational activities. This includes the dog park and boat rentals. We ask those fishing to practice catch and release.  

There is an unconfirmed but suspected presence of Blue-Green Algae. While this potentially harmful algae has not been officially confirmed, water samples have been sent to the state laboratory for testing.  

Why is the Town of Windsor Taking Precautionary Measures? 

The Town of Windsor closed Windsor Lake Reservoir to town provided activities out of an abundance of caution. At this time, the presence of blue-green algae has not been confirmed. However, Windsor Parks, Recreation & Culture staff regularly monitor lake conditions. On Friday, July 19, staff noted an increase in the algae typical to the lake. Because algae is typical and it’s concentration peaks in the fall (when swimmers are less likely present) staff acted out of the interest of public safety and issued their advisory.  

What Is Considered a Town Provided Activity?

We will not have boat rentals and have closed the dog park and concessions. While visitors are advised to use the water at their own risk, they can still enjoy the trail, volleyball net, catch and release fishing, the playground, Boardwalk Park Museum and the park in general.  

Where Can I Find Information About Other Things to Do in Windsor?

You can visit our event calendar and there are plenty of fun things listed on our website. From biking the Poudre River Trail to checking out our state-of-the-art indoor aquatic facility in the Community Recreation Center, there's never a lack of opportunities for fun and recreation in our town. 

Can I Still Choose to Swim and Kayak or Paddleboard in the Lake?

Yes. This is only a precautionary advisory and a voluntary closure of town-provided services in the interest of public safety. At this time we recommend against it especially for children, older adults and pets.   

Why is the Dog Beach Closed?

We cannot stop dogs from drinking the water and dogs can be particularly sensitive to this algae.     

When will Windsor Lake Reservoir Open Again to Recreational Use?

We have samples submitted to the state for testing and as soon as we confirm that blue-green algae is not present we will re-open. We will post information on this page, through the town’s social media platforms and remove signage from around the lake.

If the Algae is Tests Positive, What Symptoms Would It Cause? 

Humans can present a range of symptoms such as sore throat, headache, skin irritation, vomiting, diarrhea, fever, nausea, stomach cramps.   

Does the Town Test Water Valley Lake?

No. Water Valley Lake is not considered a public lake. It is part of a private Homeowners Association.  

What is Harmful Algae?

Although we haven't confirmed it, we suspect this might be known as Blue-Green Algae which are not really an algae, they are a type of bacteria, and are common in lakes throughout Colorado. The algae multiply rapidly—and are impacted by a combination of unusually sustained hot weather and stormwater runoff that includes nutrient pollution from fertilizers—to form blooms and scums.  

What Contributes to Blue-Green Algae Growth?

Polluted stormwater runoff can have adverse effects on plants, fish, animals and people. Too much nitrogen, potassium and phosphorus in the water is known as nutrient pollution and can cause algae to grow faster than ecosystems can handle. Significant increases in algae harm water quality, food resources, and decrease the oxygen aquatic life. Add sustained hot temperatures and conditions exist for this type of algae to thrive.  

How Can I Help Prevent Nutrient Pollution in Our Waterways?

  • Avoid over-applying fertilizer and don’t apply it before rain or on windy days. 
  • Use yard waste, grass clippings and fallen leaves as mulch or compost for your garden or bag them in large paper sacks.
  • Scoop the poop and put pet waste in the trash. Pet waste contains undigested and excess nutrients. 
  • Wash your car so it drains to grass or gravel instead of the street. Soap and grit run along the curb into the storm drain and directly into our rivers and lakes. Better yet, go to the car wash. The dirty water at a car wash is discharged to the wastewater sewer system—not the stormwater system—and treated. 

Water Samples

The following chart reflects the results from Colorado State University Environmental Quality Laboratory from samples collected at Windsor Lake.

The standard is for the Total E.coli count to be below 235/100 mL
Date Collected Total E.coli Count Total Fecal Coliform
07/17/2019 21 per 100 mL 28 per 100 mL
07/10/2019 49 per 100 mL 49 per 100 mL 
07/02/2019 4 per 100 mL 5 per 100 mL
06/27/2019 10 per 100 mL 10 per 100 mL
06/19/2019 0 per 100 mL 0 per 100 mL
06/13/2019 0 per 100 mL 0 per 100 mL 
06/03/2019 5 per 100 mL 5 per 100 mL
05/23/2019 0 per 100 mL 0 per 100 mL 
Located at Boardwalk Park, 100 N. 5th Street, Windsor, CO. Take a walk around the Windsor Lake Trail which surrounds the perimeter of the lake. The trail is 2.25 miles around. 

The Windsor Lake offers many opportunities for recreational activities including: 
Wind Lake KourtneyHand


*Dogs must be leashed at all times except at the Windsor Lake Dog Park located on the north side of Windsor Lake.
* Swimming is permitted within the designated Swim Beach Area ONLY marked by ropes and buoys.
* Swim diapers are requested for use with young children and are available at the concession stand.
* Ingestion of untreated agricultural water such as Windsor Lake carries an inherent risk of possible exposure to pathogenic organisms. Individuals who have been ill are asked to refrain from entering the water.
* Algae may be present.
* For your safety, it is the Town of Windsor Parks, Recreation & Culture Department's policy to not allow persons or pets on our frozen bodies of water. Although ice is tempting to walk on, temperatures rarely stay consistent enough to form stable ice. Falling through ice can cause great bodily harm or death.