Is Lake Ewauna safe to swim?

As of July 20, 2026, Lake Ewauna in Klamath County, Oregon is not recommended for swimming. Satellite imagery measured 2,979,223 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 0.4 in, which can wash bacteria and nutrients into the water.

How this read is built

Lake Ewauna is a lake in Klamath County, Oregon covering about 0.6 sq mi, the 96th-largest of the 115 lakes SwimZone monitors in Oregon. Satellite imagery measured 2,979,223 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 7 summers of satellite monitoring since 2020, Lake Ewauna has reached blue-green algae advisory levels in 7 of them, most recently in July 2026. This is a lake that blooms most summers. Its highest recorded reading was 3,956,426 cells/mL in July 2025.

Is it safe to swim in Lake Ewauna right now?

Lake Ewauna is not recommended for swimming today. Satellite imagery measured 2,979,223 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 Ewauna have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 2,979,223 cells/mL of blue-green algae (cyanobacteria) at Lake Ewauna 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 Ewauna?

No. Blue-green algae at Lake Ewauna is above the safe-contact threshold (2,979,223 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 Ewauna have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Lake Ewauna has reached blue-green algae advisory levels in 7 of them, most recently in July 2026. This is a lake that blooms most summers. Its highest recorded reading was 3,956,426 cells/mL in July 2025.

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

Today, 31 Oregon waters are above a safe-contact threshold and 1 more warrant caution, out of 213 monitored waters SwimZone tracks in the state.

How is Lake Ewauna'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 Ewauna, and a recent-rainfall overlay, all refreshed daily. It was last updated July 20, 2026.