Is Willow Lake safe to swim?

As of July 20, 2026, Willow Lake in Brown County, Nebraska carries a swim caution. Satellite imagery measured 66,561 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

Willow Lake is a lake in Brown County, Nebraska covering about 0.6 sq mi, the 43rd-largest of the 75 lakes SwimZone monitors in Nebraska. Satellite imagery measured 66,561 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, Willow 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 July 2023.

Is it safe to swim in Willow Lake right now?

Willow Lake carries a swim caution today. Satellite imagery measured 66,561 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 Willow Lake have blue-green algae (cyanobacteria)?

Low levels. Satellite monitoring measured 66,561 cells/mL at Willow 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 Willow Lake?

Use caution. Blue-green algae at Willow Lake are elevated (66,561 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 Willow Lake have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Willow 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 July 2023.

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

Today, 44 Nebraska waters are above a safe-contact threshold and 4 more warrant caution, out of 83 monitored waters SwimZone tracks in the state.

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