Windsor Lake, beach and dog park closed because of positive test for bacteria

Windsor Lake, the lake beach and dog park are closed until further notice because of a positive water test for bacteria, the town of Windsor announced Friday.

A precautionary water sample taken from the lake Wednesday returned positive for cyanobacteria, also known as blue-green algae, according to a news release from the town’s department of parks recreation and culture.

The closure went into effect Friday afternoon and affects the lake, the swim beach and access to the dog beach.

Almost one year ago — July 23, 2021 — the lake closed to the public for 17 days because of the presence of the same cyanobacteria in the water.

Rentals and concessions will not be available while the area is closed. Annual permitted motorized and non-motorized boaters are allowed on the lake to assist in agitating the water. Water activities such as tubing and water skiing are not allowed.

Non-motorized boaters may use permits at their own risk. The town recommends staying out of the water.

Blue-Green Algae, which are not really algae, are a type of bacteria and are common in lakes throughout Colorado, according to the town’s release. The algae multiply rapidly — and are impacted by a combination of unusually sustained hot weather, stagnant water and stormwater runoff that includes nutrient pollution from fertilizers — to form blooms and scums.

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.

The addition of sustained hot temperatures allow conditions for the algae to thrive.

The lake is closed, effective immediately, the swim beach is roped off, and access to the dog beach is locked.

“Earlier this week, our team took precautions and issued an advisory to our community in addition to publishing messages across our communication platforms,” ​​said Kendra Martin, Parks, Recreation & Culture Operations and Facilities Manager. “With the results returning positive for blue-green algae, staff immediately closed access to the swim areas at the lake and are actively working to keep our community aware.”

While permit holders are advised to boat at their own risk, visitors may continue to use the Dr. Tom Jones Trail, a 2.5-mile trail around the lake, in addition to the volleyball court, catch and release fishing, the playground, Boardwalk Park Museum, and the park in general.

Additional swim options include the Community Recreation Center (CRC), Chimney Park Pool, and Eastman Park River Experience. The CRC’s swim options include a pool with three lap lanes, a hot tub, a lazy river, and a water slide.

For hours of operation, admission to the pools, and information about events happening in Windsor, visit

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