Is Clark Lake safe to swim?

As of July 20, 2026, Clark Lake in Lincoln County, Oklahoma carries a swim caution. Satellite imagery measured 85,922 cells/mL of blue-green algae on July 19, 2026, elevated but below 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

Clark Lake is a lake in Lincoln County, Oklahoma covering about 0.4 sq mi, the 55th-largest of the 57 lakes SwimZone monitors in Oklahoma. Satellite imagery measured 85,922 cells/mL of blue-green algae on July 19, 2026, elevated but below 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, Clark Lake has reached blue-green algae advisory levels in 5 of them, most recently in June 2025. This is a lake that blooms most summers. Its highest recorded reading was 985,424 cells/mL in August 2024.

Is it safe to swim in Clark Lake right now?

Clark Lake carries a swim caution today. Satellite imagery measured 85,922 cells/mL of blue-green algae on July 19, 2026, elevated but below 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 Clark Lake have blue-green algae (cyanobacteria)?

Low levels. Satellite monitoring measured 85,922 cells/mL at Clark Lake on July 19, 2026, below the 100,000 cells/mL advisory threshold. Keep an eye out for surface scum, which can concentrate quickly.

Can dogs swim in Clark Lake?

Use caution. Blue-green algae at Clark Lake are elevated (85,922 cells/mL on July 19, 2026). Dogs are far more sensitive to cyanobacteria than people, so keep them out of the water and away from surface scum.

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

Over 7 summers of satellite monitoring since 2020, Clark Lake has reached blue-green algae advisory levels in 5 of them, most recently in June 2025. This is a lake that blooms most summers. Its highest recorded reading was 985,424 cells/mL in August 2024.

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