Is Deer Lake safe to swim?

As of July 20, 2026, Deer Lake in Stevens County, Washington is clear to swim. Satellite imagery detected no blue-green algae bloom as of July 19, 2026. Rainfall over the past week totaled 0.0 in, which can wash bacteria and nutrients into the water.

How this read is built

Deer Lake is a lake in Stevens County, Washington covering about 1.8 sq mi, the 42nd-largest of the 112 lakes SwimZone monitors in Washington. Satellite imagery detected no blue-green algae bloom as of July 19, 2026.

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, Deer Lake has reached blue-green algae advisory levels in 7 of them, most recently in June 2026. This is a lake that blooms most summers. Its highest recorded reading was 1,946,718 cells/mL in August 2021.

Is it safe to swim in Deer Lake right now?

Deer Lake is clear to swim today. Satellite imagery detected no blue-green algae bloom as of July 19, 2026. Conditions can change quickly with wind, heat, and rain, so check the posted signs and look at the water before you get in.

Does Deer Lake have blue-green algae (cyanobacteria)?

No blue-green algae bloom is detectable at Deer Lake as of July 19, 2026 (below the satellite's roughly 10,000 cells/mL detection limit). Cyanobacteria can still appear within hours in warm, calm, nutrient-rich water, so look before you swim.

Can dogs swim in Deer Lake?

No bloom is detected at Deer Lake 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 Deer Lake have blue-green algae blooms?

Over 7 summers of satellite monitoring since 2020, Deer Lake has reached blue-green algae advisory levels in 7 of them, most recently in June 2026. This is a lake that blooms most summers. Its highest recorded reading was 1,946,718 cells/mL in August 2021.

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

Today, 18 Washington waters are above a safe-contact threshold and 9 more warrant caution, out of 1348 monitored waters SwimZone tracks in the state.

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