How this works
Every number on this site is Metro Vancouver's own measurement, presented plainly. This page explains where the data comes from, how often it updates, what the numbers mean, and what they cannot tell you.
- Advisory threshold
- 200 E. coli / 100 mL
- Sampling season
- April – September
- Sampling frequency
- About once a week
- Site data refreshed
- Every Friday
Where the data comes from
Every reading comes from Metro Vancouver's beach water quality monitoring programme. We retrieve it from their public ArcGIS REST services, the same services that power Metro Vancouver's own beach map. We do not collect, sample, or test anything ourselves.
The two services: Beach_Site_Area (the 41 monitored beaches) and Historical_Data (every 30-day geometric mean recorded since 2015), both under gis.metrovancouver.org. https://gis.metrovancouver.org/arcgis/rest/services
Data source: Metro Vancouver, Beaches and Recreational Water Quality Monitoring.
How the data stays current
Metro Vancouver samples during the swimming season and posts results weekly, usually Thursday. Every Friday morning an automated job retrieves the full dataset, checks it for completeness, rejecting any malformed or truncated response, and redeploys the site with the fresh readings.
Between refreshes, the site re-evaluates the age of every reading daily. If a beach stops being sampled, its assessment is withdrawn within a day. It is never allowed to keep an out-of-date verdict.
Data currently shown was retrieved on July 21, 2026.
What the number means
Each value is a 30-day geometric mean of E. coli concentration, measured in colony-forming units per 100 mL of water. It is not a single sample and not a same-day reading. It summarises the previous thirty days.
British Columbia's recreational water quality guideline sets a geometric-mean advisory threshold of 200 E. coli per 100 mL. A separate single-sample threshold of 400 also exists in the guideline, but single-sample data is not published in this dataset and is not shown here.
Why some beaches show no reading
Sampling runs from April through September. Outside that season, the most recent reading may be many months old. Rather than colour a beach green on stale data, we show no assessment at all when the last sample is more than 14 days old.
What this site cannot tell you
Water quality changes faster than it is measured. A reading taken last week says nothing definitive about the water today, particularly after heavy rain, which flushes contaminants into the sea. A 30-day mean can sit comfortably below the threshold while a single day within it was badly contaminated.
This site is an independent presentation of public data. It is not an advisory service and carries no official status. Swimming advisories are issued by Vancouver Coastal Health and Fraser Health, and their guidance supersedes anything shown here.
Accessibility
This site conforms to WCAG 2.1 Level AA, verified with automated audits on every page in both languages. Water quality status is never conveyed by colour alone: every beach carries a text label and a distinct icon. The list presents the same information as the map, and every interactive element is reachable by keyboard.
If you encounter a barrier using this site, write to us at accessibility@corvustech.ca and we will fix it.
Privacy
This site collects no personal information. There are no accounts, no forms, no cookies, no advertising, and no analytics or tracking scripts of any kind. Your visit is not recorded by us.
Map tiles are served by CARTO, whose servers receive the standard technical information any web request carries. No other third party is contacted by your browser when you use this site.
Who built this
Corvus Tech, a software consultancy in British Columbia. We built this to demonstrate that public data can be presented clearly, accessibly, and in both official languages.