Is Lake Eucha safe to swim?

As of July 20, 2026, Lake Eucha in Delaware County, Oklahoma is not recommended for swimming. Satellite imagery measured 267,241 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 0.5 in, which can wash bacteria and nutrients into the water.

How this read is built

Lake Eucha is a lake in Delaware County, Oklahoma covering about 4.3 sq mi, the 26th-largest of the 57 lakes SwimZone monitors in Oklahoma. Satellite imagery measured 267,241 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 Eucha has reached blue-green algae advisory levels in 2 of them, most recently in September 2025. Blooms here have been occasional rather than annual. Its highest recorded reading was 681,496 cells/mL in September 2025.

Is it safe to swim in Lake Eucha right now?

Lake Eucha is not recommended for swimming today. Satellite imagery measured 267,241 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 Eucha have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 267,241 cells/mL of blue-green algae (cyanobacteria) at Lake Eucha 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 Eucha?

No. Blue-green algae at Lake Eucha is above the safe-contact threshold (267,241 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 Eucha have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Lake Eucha has reached blue-green algae advisory levels in 2 of them, most recently in September 2025. Blooms here have been occasional rather than annual. Its highest recorded reading was 681,496 cells/mL in September 2025.

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

Today, 22 Oklahoma waters are above a safe-contact threshold and 2 more warrant caution, out of 64 monitored waters SwimZone tracks in the state.

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