Island Health works with local governments and agencies to monitor water quality at popular public beaches in order to protect recreational water users from illnesses linked to unacceptable levels of bacteria.
Indicator bacteria are used to identify the presence of fecal contamination and provides an indication of potential risks associated with swimming or other recreational water activities in that location. The indicator bacteria used depends on the type of water sampled. E.coli is used for fresh water beaches and Enterococci is used for salt water beaches.
Sampling frequencies are based on beach usage, previous sample results and potential sources of contamination. Risk Ratings are as follows:
- HIGH -sampled weekly
- MODERATE - sampled every 2 weeks
- LOW - sampled monthly
Acceptable Sample Results
The following results are considered acceptable for recreational beach water
E.coli (Fresh Water)
- Geometric mean (minimum of 5 samples) is less than or equal to 200 E.coli per 100 ml sample
- Single sample is less than or equal to 400 E.coli per 100 ml sample
Enterococci (Marine Water)
- Geometric mean (minimum of 5 samples) is less than or equal to 35 Enterococci per 100 ml sample
- Single-sample is less than or equal to 70 Enterococci per 100 ml sample
Interpreting Sample Reports
Beach water samples are reported using the following coding system
- GTR200 ~ Greater than 200 background colonies on membrane filter per 100 ml of sample.
- LT0 ~ Less than
- LT1 ~ Less than 1
- LT5 ~ Less than 5
- LT10 ~ Less than 10
- LT50 ~ Less than 50
- LT100 ~ Less than 100
- GRTR ~ Greater than
- ESTCT ~ Estimated Count
- ESTHCD ~ High colony density on membrane prevented accurate coliform count.
- OGO ~ Overgrown.
- OGCOL ~ Overgrown with coliform present.
- OGECOL ~ Overgrown with E. coli present.
- OVEREN ~ Overgrown with Enterococci present.
- OGC ~ Result indicates confluent bacterial growth preventing accurate coliform determination. Re sample for MPN testing by indicating Previous Sample Overgrown.
- PRELIM ~ Preliminary report
- FINRPT ~ Final Report
- REJCT ~ Sample rejected
- LKS2 ~ Sample leaked in transit. Sample not processed. Please repeat collection.
- HPCND ~ Heterotrophic plate count was not performed. Sample was not received on day of collection.
- DELAY3 ~ Sample not tested too long in transit.
- NRLABE ~ No result available due to laboratory error. Please recollect sample.
- SANOTE ~ Sample not tested.
- SAREF ~ Sample received frozen. Result may not be valid.
- SAREPF ~ Sample received partially frozen. Result may not be valid.
- EMPTY ~ Sample bottle received empty.
- QRWRT ~ Sample exceeded 30 hours from time of collection, results may not be valid. No written report will be issued and only a qualitative result will be reported by telephone when test is completed.
- DISR ~ Disregard previous reported results
- MAMEND ~ Please note: An Amended Report
- NSR ~ No sample received
- OIE ~ Ordered in Error
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