Reservoir · Hampden County · MA
Is Springfield Reservoir 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 Springfield Reservoir right now
As of July 20, 2026, Springfield Reservoir in Hampden County, Massachusetts is not recommended for swimming. Satellite imagery measured 184,817 cells/mL of blue-green algae on July 19, 2026, above the 100,000 cells/mL advisory threshold. Rainfall over the past week totaled 0.2 in, which can wash bacteria and nutrients into the water.
Blue-green algae at Springfield Reservoir
Springfield Reservoir is a reservoir in Hampden County, Massachusetts. Satellite imagery measured 184,817 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 Springfield Reservoir
From EPA CyAN's satellite archive
Over 7 summers of satellite monitoring since 2020, Springfield Reservoir has reached blue-green algae advisory levels in 6 of them, most recently in September 2025. This is a lake that blooms most summers. Its highest recorded reading was 1,551,469 cells/mL in June 2022.
Frequently asked: swimming in Springfield Reservoir
- Is it safe to swim in Springfield Reservoir right now?
- Springfield Reservoir is not recommended for swimming today. Satellite imagery measured 184,817 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 Springfield Reservoir have blue-green algae (cyanobacteria)?
- Yes. Satellite monitoring measured 184,817 cells/mL of blue-green algae (cyanobacteria) at Springfield Reservoir 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 Springfield Reservoir?
- No. Blue-green algae at Springfield Reservoir is above the safe-contact threshold (184,817 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 Springfield Reservoir have blue-green algae blooms?
- Over 7 summers of satellite monitoring since 2020, Springfield Reservoir has reached blue-green algae advisory levels in 6 of them, most recently in September 2025. This is a lake that blooms most summers. Its highest recorded reading was 1,551,469 cells/mL in June 2022.
- How many Massachusetts lakes and beaches are unsafe for swimming today?
- Today, 5 Massachusetts waters are above a safe-contact threshold and 246 more warrant caution, out of 608 monitored waters SwimZone tracks in the state.
- How is Springfield Reservoir'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 Springfield Reservoir, and a recent-rainfall overlay, all refreshed daily. It was last updated July 20, 2026.