Is Hauser Lake safe to swim?

As of July 20, 2026, Hauser Lake in Lewis and Clark County, Montana is clear to swim. Satellite imagery measured 11,145 cells/mL of blue-green algae on July 19, 2026, well 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.

How this read is built

Hauser Lake is a lake in Lewis and Clark County, Montana covering about 5 sq mi, the 20th-largest of the 124 lakes SwimZone monitors in Montana. Satellite imagery measured 11,145 cells/mL of blue-green algae on July 19, 2026, well 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.

Over 7 summers of satellite monitoring since 2020, Hauser Lake 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 905,030 cells/mL in July 2023.

Is it safe to swim in Hauser Lake right now?

Hauser Lake is clear to swim today. Satellite imagery measured 11,145 cells/mL of blue-green algae on July 19, 2026, well 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 Hauser Lake have blue-green algae (cyanobacteria)?

Low levels. Satellite monitoring measured 11,145 cells/mL at Hauser 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 Hauser Lake?

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

Over 7 summers of satellite monitoring since 2020, Hauser Lake 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 905,030 cells/mL in July 2023.

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

Today, 19 Montana waters are above a safe-contact threshold and 2 more warrant caution, out of 135 monitored waters SwimZone tracks in the state.

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