River · Greenwood County · KS
Is Fall River Lake safe to swim?
Cyanobacteria conditions are elevated; use caution.
Updated July 20, 2026 · EPA CyAN satellite
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What's in the water at Fall River Lake right now
As of July 20, 2026, Fall River Lake in Greenwood County, Kansas carries a swim caution. Satellite imagery measured 96,246 cells/mL of blue-green algae on July 19, 2026, elevated but below 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 Fall River Lake
Fall River Lake is a lake in Greenwood County, Kansas covering about 3.7 sq mi, the 18th-largest of the 28 lakes SwimZone monitors in Kansas. Satellite imagery measured 96,246 cells/mL of blue-green algae on July 19, 2026, elevated but 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.
Bloom history at Fall River Lake
From EPA CyAN's satellite archive
Over 7 summers of satellite monitoring since 2020, Fall River Lake has reached blue-green algae advisory levels in 3 of them, most recently in September 2024. Its highest recorded reading was 397,542 cells/mL in September 2024.
Frequently asked: swimming in Fall River Lake
- Is it safe to swim in Fall River Lake right now?
- Fall River Lake carries a swim caution today. Satellite imagery measured 96,246 cells/mL of blue-green algae on July 19, 2026, elevated but 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 Fall River Lake have blue-green algae (cyanobacteria)?
- Low levels. Satellite monitoring measured 96,246 cells/mL at Fall River Lake 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 Fall River Lake?
- Use caution. Blue-green algae at Fall River Lake are elevated (96,246 cells/mL on July 19, 2026). Dogs are far more sensitive to cyanobacteria than people, so keep them out of the water and away from surface scum.
- How often does Fall River Lake have blue-green algae blooms?
- Over 7 summers of satellite monitoring since 2020, Fall River Lake has reached blue-green algae advisory levels in 3 of them, most recently in September 2024. Its highest recorded reading was 397,542 cells/mL in September 2024.
- How many Kansas lakes and beaches are unsafe for swimming today?
- Today, 10 Kansas waters are above a safe-contact threshold and 1 more warrant caution, out of 30 monitored waters SwimZone tracks in the state.
- How is Fall River 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 Fall River Lake, and a recent-rainfall overlay, all refreshed daily. It was last updated July 20, 2026.