Is Jeff Lake safe to swim?

As of July 20, 2026, Jeff Lake in Avoyelles County, Louisiana is not recommended for swimming. Satellite imagery measured 2,442,660 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

Jeff Lake is a lake in Avoyelles County, Louisiana covering about 0.5 sq mi, the 186th-largest of the 215 lakes SwimZone monitors in Louisiana. Satellite imagery measured 2,442,660 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, Jeff Lake has reached blue-green algae advisory levels in 6 of them, most recently in June 2026. This is a lake that blooms most summers. Its highest recorded reading was 4,825,508 cells/mL in September 2023.

Is it safe to swim in Jeff Lake right now?

Jeff Lake is not recommended for swimming today. Satellite imagery measured 2,442,660 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 Jeff Lake have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 2,442,660 cells/mL of blue-green algae (cyanobacteria) at Jeff 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 Jeff Lake?

No. Blue-green algae at Jeff Lake is above the safe-contact threshold (2,442,660 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 Jeff Lake have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Jeff Lake has reached blue-green algae advisory levels in 6 of them, most recently in June 2026. This is a lake that blooms most summers. Its highest recorded reading was 4,825,508 cells/mL in September 2023.

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

Today, 69 Louisiana waters are above a safe-contact threshold and 36 more warrant caution, out of 265 monitored waters SwimZone tracks in the state.

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