Reservoir · Hancock County · OH
Is Findlay Upground Reservoir Number Two safe to swim?
Blue-green algae is above the safe-contact threshold.
Updated July 20, 2026 · EPA CyAN satellite
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What's in the water at Findlay Upground Reservoir Number Two right now
As of July 20, 2026, Findlay Upground Reservoir Number Two in Hancock County, Ohio is not recommended for swimming. Satellite imagery measured 104,796 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 0.0 in, which can wash bacteria and nutrients into the water.
Blue-green algae at Findlay Upground Reservoir Number Two
Findlay Upground Reservoir Number Two is a reservoir in Hancock County, Ohio covering about 1 sq mi, the 28th-largest of the 42 lakes SwimZone monitors in Ohio. Satellite imagery measured 104,796 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.
Bloom history at Findlay Upground Reservoir Number Two
From EPA CyAN's satellite archive
Over 6 summers of satellite monitoring since 2020, Findlay Upground Reservoir Number Two has reached blue-green algae advisory levels in 5 of them, most recently in September 2025. This is a lake that blooms most summers. Its highest recorded reading was 1,308,648 cells/mL in September 2020.
Frequently asked: swimming in Findlay Upground Reservoir Number Two
- Is it safe to swim in Findlay Upground Reservoir Number Two right now?
- Findlay Upground Reservoir Number Two is not recommended for swimming today. Satellite imagery measured 104,796 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 Findlay Upground Reservoir Number Two have blue-green algae (cyanobacteria)?
- Yes. Satellite monitoring measured 104,796 cells/mL of blue-green algae (cyanobacteria) at Findlay Upground Reservoir Number Two 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 Findlay Upground Reservoir Number Two?
- No. Blue-green algae at Findlay Upground Reservoir Number Two is above the safe-contact threshold (104,796 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 Findlay Upground Reservoir Number Two have blue-green algae blooms?
- Over 6 summers of satellite monitoring since 2020, Findlay Upground Reservoir Number Two has reached blue-green algae advisory levels in 5 of them, most recently in September 2025. This is a lake that blooms most summers. Its highest recorded reading was 1,308,648 cells/mL in September 2020.
- How many Ohio lakes and beaches are unsafe for swimming today?
- Today, 26 Ohio waters are above a safe-contact threshold and 12 more warrant caution, out of 100 monitored waters SwimZone tracks in the state.
- How is Findlay Upground Reservoir Number Two'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 Findlay Upground Reservoir Number Two, and a recent-rainfall overlay, all refreshed daily. It was last updated July 20, 2026.