State Water Board research data specialist Michelle Tang demonstrated a redesigned Safe2Swim map that aggregates beach bacteria monitoring from BeachWatch, Seiden and the Central Valley E. coli monitoring map and presents site-level "safety status" for recreators.

"We are assigning it a low risk category" when recent single-sample results and the six-week geometric mean do not exceed statewide bacteria thresholds, Tang said during her live demo. The prototype uses three status categories: blue for low risk, orange for "use caution" where at least one metric exceeds thresholds, and gray for "not enough data."

Tang said the map adds new bulk-upload fields to match CDN2 requirements (sample agency code, lab agency code, lab batch analysis date, a "detected above MDL" field, and QA codes), will use controlled vocabulary lists to reduce misinterpretation, and will implement filter-and-logic validation rules to catch duplicates and missing required fields. The Water Board's IT team plans testing in the current month and December; staff expect the BeachWatch update to complete in December with optional agency office hours in January.

On update cadence and data currency, Tang said the system is designed for a daily refresh on workdays but that some IT processes could create intermittent delays. She also said integrating harmful algal bloom (HAB) postings and beach closure/advisory notifications is a long-term goal, and that adding local datasets (for example, San Francisco Public Utilities Commission monitoring) is feasible and under consideration.

Tang asked for feedback on public messaging and data interpretation; she offered a test site for reviewers and said a public go-live could be targeted for late winter or early spring depending on feedback and management approvals. Tang provided a link to the Python script used to standardize multi-source data and to the open data portal where the full Safe2Swim dataset will be published.

The presentation concluded with attendees asking about daily refresh expectations, HAB coverage, and how risk messaging will align with county health-officer postings. Tang said she welcomes continuing feedback and will share the presentation and contact details with attendees.