Is Lake De Cade safe to swim?

As of July 20, 2026, Lake De Cade in Terrebonne County, Louisiana is not recommended for swimming. Satellite imagery measured 179,648 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 4.8 in, which can wash bacteria and nutrients into the water.

How this read is built

Lake De Cade is a lake in Terrebonne County, Louisiana covering about 7.7 sq mi, the 22nd-largest of the 215 lakes SwimZone monitors in Louisiana. Satellite imagery measured 179,648 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Larger, warmer waters like this can hold a bloom for weeks once nutrients and calm weather line up.

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, Lake De Cade has reached blue-green algae advisory levels in 3 of them, most recently in August 2025. Its highest recorded reading was 608,391 cells/mL in August 2024.

Is it safe to swim in Lake De Cade right now?

Lake De Cade is not recommended for swimming today. Satellite imagery measured 179,648 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 Lake De Cade have blue-green algae (cyanobacteria)?

Yes. Satellite monitoring measured 179,648 cells/mL of blue-green algae (cyanobacteria) at Lake De Cade 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 Lake De Cade?

No. Blue-green algae at Lake De Cade is above the safe-contact threshold (179,648 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 Lake De Cade have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Lake De Cade has reached blue-green algae advisory levels in 3 of them, most recently in August 2025. Its highest recorded reading was 608,391 cells/mL in August 2024.

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