Did you know public beaches in Gallatin County are regularly monitored for potential health risks? The Recreational Waters Bacterial Monitoring Program collects water samples from public beaches and looks at their bacterial loads during times of peak use. Depending on the results, this group takes the necessary corrective actions that will help protect the public and their health.

Meyers Lake Water Sample Results

Sample Dates # of Samples Geometric Mean
(mpn E. Coli/100ml)
Max Value
(mpn E. Coli/100ml)
August 8, 2023 2 195.35 547.5
July 31, 2023 2 130.77 344.8
July 11, 2023 2 365.9 435.2
June 27, 2023 6 190.8 488.4

Color Key:

E. coli Levels Recommendations
CAUTION: E. coli levels are below EPA recreational water quality standards for full body contact swimming. Take standard precautions. Do not drink the water.
WARNING: E. coli levels are ABOVE the EPA recreational water quality standards for full body contact swimming. Avoid swimming. Wash hands after contact. Do not drink the water.

What’s a good result?

Results that are below a geometric mean of 126 colonies per 100mL or below 235 organisms per 100mL for a single sample mean you should take standard precautions when swimming in the water and avoid drinking the water. In addition, sample collections only happen during one week per month. This means there are limitations to assuming the water is safe for the rest of the month.

Overview of the Recreational Waters Bacterial Monitoring Program

  • The City of Bozeman Recreation Department collects surface water samples at beaches on a regular basis,
  • The City of Bozeman’s Water Reclamation Facility tests the surface water samples for the presence of E. coli bacteria,
  • Gallatin City-County Health Department notifies the public of the water sample results via this website, and other public advisory channels as needed.

Monitoring and Water Quality Standards

Once per month, water sampling occurs for five consecutive days, between June and September. Water sampling frequency may vary depending on the season and circumstances. A laboratory receives the water samples and tests for the presence of E. coli bacteria, measured by cfu, or colony-forming unit, which estimates the number of viable bacteria in the sample.

The EPA recommends a recreational water quality standard for full-body contact swimming for E. coli is 235 organisms per 100 mL for any single sample or a geometric mean of 126 colonies per 100 mL for all tested water samples collected during a sampling period. If the bacterial results exceed either of these values, the Gallatin City-County Health Department will take action to inform the public of the associated health risks.

If you have any questions or concerns, please contact the Gallatin City-County Health Department at 406.582.3120 or the Gallatin Local Water Quality District at 406.582.3168.

For more details about the monitoring process, please see the Recreational Waters Bacterial Monitoring Sampling and Analysis Plan.