Beach Water Quality


Bacteria Monitoring

Ramsey County regularly tests beaches for water quality during beach season, from June through August each year. Learn more about the most commonly tested for contaminant - E. coli. 
Ramsey County uses the E. coli water quality standard to identify water bodies that may be contaminated with fecal waste. Higher levels of E. coli in the water may or may not be accompanied by higher levels and an increased risk of harmful bacteria; varying survival rates of bacteria make it impossible to definitively state when these harmful bacteria are present. Two samples are taken from each Ramsey County beach weekly to test E. coli levels.
See the Minnesota Department of Health Waterborne Illness web page for more information on how to reduce your risk to waterborne illnesses when swimming, boating or wading.
As a safety precaution, Ramsey County will close a beach area if:
  • sample mean exceeds 1260 E. coli organisms per 100 mL sample (single-sample limit),
  • Or if five samples equally spaced over a 30-day period have an average of more than 126 organisms per 100 mL sample (geometric mean). 
Beaches will reopen when sample levels are back within state guidelines. 
Notes: Snail Lake is currently closed due to high water. Ramsey County tests the water at but does not manage  Mahtomedi Beach and Lake Phalen.
Elevated bacteria levels generally occur after rain events when bacteria from various sources are washed into the lakes. Potential sources of E. coli in lake water include: 
  • Beach sand.
  • Wild and domestic animal waste.
  • Organic debris, such as decomposing leaves.
  • Water from streams.
  • Polluted stormwater runoff. 
  • Sewage spills near the beach. 
  • Sewer line breaks. 
  • Leaking diapers, bather defecation.

Test Results over Time

Single Day Sample Mean by Beach 

If the one-day sample mean exceeds 1260 organisms per 100 mL sample,  the beach will be closed. 
Each colored line represents a beach. The gray dotted line represents the beach closure point.

30-Day Sample Mean
by Beach 

If the 30-day sample mean exceeds 126 organisms per 100 mL sample,  the beach will be closed. 
Each colored line represents a beach. The gray dotted line represents the beach closure point.

Raw Data

Visit the complete dataset to visualize and download the data yourself.

Visit Minnesota Polution Control Agency for more information on surface water quality and to search by lake.