Is Lake Ashby safe to swim?

As of July 20, 2026, Lake Ashby in Volusia County, Florida is clear to swim. Satellite imagery measured 17,055 cells/mL of blue-green algae on July 19, 2026, well below the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 1.4 in, which can wash bacteria and nutrients into the water.

How this read is built

Lake Ashby is a lake in Volusia County, Florida covering about 1.4 sq mi, the 92nd-largest of the 230 lakes SwimZone monitors in Florida. Satellite imagery measured 17,055 cells/mL of blue-green algae on July 19, 2026, well 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, Lake Ashby has reached blue-green algae advisory levels in 3 of them, most recently in July 2025. Its highest recorded reading was 905,030 cells/mL in July 2025.

Is it safe to swim in Lake Ashby right now?

Lake Ashby is clear to swim today. Satellite imagery measured 17,055 cells/mL of blue-green algae on July 19, 2026, well 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 Lake Ashby have blue-green algae (cyanobacteria)?

Low levels. Satellite monitoring measured 17,055 cells/mL at Lake Ashby 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 Lake Ashby?

No bloom is detected at Lake Ashby today, but dogs are much more vulnerable to blue-green algae than people, and blooms can form within hours. Always keep dogs away from water that looks green, scummy, or discolored, and rinse them off after swimming.

How often does Lake Ashby have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Lake Ashby has reached blue-green algae advisory levels in 3 of them, most recently in July 2025. Its highest recorded reading was 905,030 cells/mL in July 2025.

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

Today, 97 Florida waters are above a safe-contact threshold and 350 more warrant caution, out of 779 monitored waters SwimZone tracks in the state.

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