Is Lake Waramaug safe to swim?

As of July 20, 2026, Lake Waramaug in Litchfield County, Connecticut is not recommended for swimming. Satellite imagery measured 543,129 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 0.0 in, which can wash bacteria and nutrients into the water.

How this read is built

Lake Waramaug is a lake in Litchfield County, Connecticut covering about 1 sq mi, the 7th-largest of the 17 lakes SwimZone monitors in Connecticut. Satellite imagery measured 543,129 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold.

Blue-green algae (cyanobacteria) blooms are most common from midsummer into early fall, when the water is warm, calm, and rich in nutrients from runoff. They can produce toxins that make people sick and can be rapidly fatal to dogs, so skip water that looks green, scummy, or like spilled paint, and keep children and pets out of it.

Over 6 summers of satellite monitoring since 2020, Lake Waramaug has reached blue-green algae advisory levels in 2 of them, most recently in July 2023. Blooms here have been occasional rather than annual. Its highest recorded reading was 432,856 cells/mL in July 2023.

Is it safe to swim in Lake Waramaug right now?

Lake Waramaug is not recommended for swimming today. Satellite imagery measured 543,129 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Conditions can change quickly with wind, heat, and rain, so check the posted signs and look at the water before you get in.

Does Lake Waramaug have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 543,129 cells/mL of blue-green algae (cyanobacteria) at Lake Waramaug on July 19, 2026, above the 100,000 cells/mL advisory level. Avoid swimming and keep children and pets out of the water.

Can dogs swim in Lake Waramaug?

No. Blue-green algae at Lake Waramaug is above the safe-contact threshold (543,129 cells/mL on July 19, 2026). Cyanobacteria toxins can be rapidly fatal to dogs, which swallow it while swimming and lick it from their fur. Keep dogs out of the water and away from any scum along the shore.

How often does Lake Waramaug have blue-green algae blooms?

Over 6 summers of satellite monitoring since 2020, Lake Waramaug has reached blue-green algae advisory levels in 2 of them, most recently in July 2023. Blooms here have been occasional rather than annual. Its highest recorded reading was 432,856 cells/mL in July 2023.

How many Connecticut lakes and beaches are unsafe for swimming today?

Today, 3 Connecticut waters are above a safe-contact threshold and 27 more warrant caution, out of 92 monitored waters SwimZone tracks in the state.

How is Lake Waramaug's water quality measured?

SwimZone builds this read from EPA CyAN satellite imagery for blue-green algae, official beach and fecal-bacteria advisories where a program monitors Lake Waramaug, and a recent-rainfall overlay, all refreshed daily. It was last updated July 20, 2026.