Is Glenn Flint Lake safe to swim?

As of July 20, 2026, Glenn Flint Lake in Putnam County, Indiana is not recommended for swimming. Satellite imagery measured 543,129 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 0.6 in, which can wash bacteria and nutrients into the water.

How this read is built

Glenn Flint Lake is a lake in Putnam County, Indiana covering about 0.6 sq mi, the 40th-largest of the 53 lakes SwimZone monitors in Indiana. Satellite imagery measured 543,129 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, Glenn Flint Lake has reached blue-green algae advisory levels in 7 of them, most recently in June 2026. This is a lake that blooms most summers. Its highest recorded reading was 1,839,344 cells/mL in May 2020.

Is it safe to swim in Glenn Flint Lake right now?

Glenn Flint Lake is not recommended for swimming today. Satellite imagery measured 543,129 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 Glenn Flint Lake have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 543,129 cells/mL of blue-green algae (cyanobacteria) at Glenn Flint 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 Glenn Flint Lake?

No. Blue-green algae at Glenn Flint Lake is above the safe-contact threshold (543,129 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 Glenn Flint Lake have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Glenn Flint Lake has reached blue-green algae advisory levels in 7 of them, most recently in June 2026. This is a lake that blooms most summers. Its highest recorded reading was 1,839,344 cells/mL in May 2020.

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

Today, 20 Indiana waters are above a safe-contact threshold and 5 more warrant caution, out of 81 monitored waters SwimZone tracks in the state.

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