Lake · Calhoun County · IA
Is North Twin Lake safe to swim?
Clear to swim
No advisory or algae bloom reported for this water today.
Updated July 18, 2026 · EPA CyAN satellite
Recent rain
0.0 in
Water type
Lake
Last updated
Jul 18
Bacteria
E. coli, fecal
Tested
Not monitored
Blue-green algae
cyanobacteria
Tested
13,677
cells/mL
Advisory over
100,000
cells/mL
Sampled Jul 11 · EPA CyAN satellite
Before you get in
Conditions change fast. Blooms and bacteria move with wind, rain, and runoff, and monitoring lags real time, so always look before you get in.
Skip water that is scummy or discolored, and keep children and dogs out of visible algae.
SwimZone for iPhone · launching soon
Know before you get in at North Twin Lake.
Get an alert the day a bacteria or algae advisory goes up.