Beach Sampling Methods - Sampling and Inspection Frequency

All public bathing beaches* are sampled on a weekly basis from the first week of June (weather permitting) to Labour Day Weekend.

All public bathing beaches are inspected once per year prior to opening to determine possible sources of pollution and to determine the sampling sites.

Sampling Procedure

Beaches are sampled at 152 metre (500 feet) intervals along the beach. Any suspected source of pollution such as a stream, drainage ditch, etc. is also sampled.

Weather conditions, rainfall, temperature, wind direction and water conditions are noted at each beach site.

To protect staff, if water conditions are hazardous, (i.e. waves over one metre), the samples are not taken and the beach will be sampled when the conditions are safe.

Sampling Technique

Samples are taken at a water depth of one to one and a quarter metres (1 to ¼ metres)

The sample bottle is placed 15 cm (6 inches) to 30 cm (12 inches) below the surface and the bottle is moved away from the sampler against the prevailing current in the water.

The bottles are labelled with permanent marker and stored in a cooler with ice packs and maintained at 10° C or below until placed in the refrigerator at the Health Unit.

Samples are sent to the Public Health Laboratory within 24 hours of collection.

Beach Posting

Once the results are received from the laboratory, the results are entered into a computer program that calculates the geometric mean (the average) of the E.coli count per 100 millilitres for each beach.

If the geometric mean (average) of the E.coli count for a beach is greater than 2, that is an average E.coli count of greater than 100 E.coli per 100 millilitres of water, the beach is posted**, warning swimmers that the beach is unfit for swimming.

The sign posted on the beach states: Warning, Unsafe for Bathing, High levels of bacteria. Click here to view sign.

The beach is sampled daily (Monday to Friday) and when the geometric mean of the E.coli count is below 2, that is an average E.coli count of less than 100 E.coli per 100 millilitres of water, the sign is removed.

*Public Bathing Beach   A beach that is accessible to the public and where the public actually use the beach. This does not include private beaches where access is restricted to the cottage owners or club members, etc. or where beaches are only accessible by boat, all terrain vehicles, etc. Owners of private beaches can send water samples to private laboratories for analysis.
 **Posted  A beach is posted when the geometric mean (average) of two consecutive sample results is greater than 2, that is an average E.coli count greater than 100 E.coli per 100 millilitres of water. The beach is sampled daily (Monday to Friday) and the sign is removed when the geometric mean (average) is below 2, that is an average E.coli count below 100 E.coli per 100 millilitres of water. 

Tips and More Information on Public Bathing Beaches

The Problem

Swimming in a beach that is posted could cause a number of health problems from skin infections and rashes to eye and ear infections, and if swallowed, can cause severe diarrhea and vomiting and severe illness if the E.coli strain 01517:H7 is present.  

Lag Time

There is approximately 48 hours lag time from the time the samples are taken until the results are available. It takes time to get the samples to the laboratory and run the tests.   

A Good Rule

It is well documented that the bacterial counts (E.coli) can go up after heavy rainfalls as contaminated water from flooded private septic systems, polluted ditches, fields and manure piles, etc. drains into the lake. Therefore, a good rule is not to swim in the lake for a least 24 hours after a heavy rainfall or when the water is very rough, particularly in areas with development (urban centres and cottage areas), or any beach where a stream, river or storm drain empties into the lake.