Is Okamanpeedan Lake safe to swim?

As of July 20, 2026, Okamanpeedan Lake in Iowa is not recommended for swimming. Satellite imagery measured 2,002,733 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

Okamanpeedan Lake is a lake in Iowa covering about 3.5 sq mi, the 7th-largest of the 42 lakes SwimZone monitors in Iowa. Satellite imagery measured 2,002,733 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, Okamanpeedan Lake 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 3,633,649 cells/mL in September 2022.

Is it safe to swim in Okamanpeedan Lake right now?

Okamanpeedan Lake is not recommended for swimming today. Satellite imagery measured 2,002,733 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 Okamanpeedan Lake have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 2,002,733 cells/mL of blue-green algae (cyanobacteria) at Okamanpeedan Lake 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 Okamanpeedan Lake?

No. Blue-green algae at Okamanpeedan Lake is above the safe-contact threshold (2,002,733 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 Okamanpeedan Lake have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Okamanpeedan Lake 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 3,633,649 cells/mL in September 2022.

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

Today, 31 Iowa waters are above a safe-contact threshold and 1 more warrant caution, out of 46 monitored waters SwimZone tracks in the state.

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