Marin

Inkwells

Good to swim today.
Last sampled May 18, 2026 · 15 days ago

One or more bacteria readings exceeded EPA thresholds in the most recent sample. See the readings below for which indicator and how far above the limit.

Plate I: Location

Ninety days of readings.

Log scale · MPN/100mL

Each dot is one sample taken by the monitoring agency. The dashed brick line marks the EPA single-sample limit.

SafeCautionUnsafe

Common questions.

Is Inkwells safe to swim today?
Inkwells is currently safe for swimming. One or more bacteria readings exceeded EPA thresholds in the most recent sample. See the readings below for which indicator and how far above the limit.
When was Inkwells last tested?
The most recent water-quality sample at Inkwells was collected on May 18, 2026 (15 days ago). California monitoring agencies test Bay Area beaches weekly during swim season (roughly May through October).
What is the bacteria level at Inkwells?
The latest reading at Inkwells shows 30-day enterococcus geomean at 77 MPN/100mL (EPA geomean limit: 35); E. coli at 135 MPN/100mL (EPA single-sample limit: 235); and enterococcus at 20 MPN/100mL (EPA single-sample limit: 104).
Does rain affect water quality at Inkwells?
Yes. Heavy rainfall washes bacteria and pollutants from land into the water, raising contamination risk for 24–72 hours. The past 48 hours recorded 0.00 in of rain; the past 72 hours recorded 0.00 in. Our advisory threshold is ≥1.00 in over 48h (or ≥0.50 in over 72h) for enclosed or storm-drain beaches.
Where is Inkwells located?
Inkwells is located in the Marin area of the San Francisco Bay region (coordinates: 38.0050°N, 122.7082°W). You can get turn-by-turn directions via Google Maps or Apple Maps directly from this page.
How is the water quality data for Inkwells collected?
Bacteria samples are collected by California state and county health agencies under the AB 411 Safe-to-Swim program and reported to the state's Safe-to-Swim database (data.ca.gov). Rainfall figures come from Open-Meteo forecast and archive data. Bay Area Swim aggregates both sources and updates every morning.

Also nearby

Data: California Safe-to-Swim (ODbL 1.0) · Open-Meteo — Precipitation (CC-BY 4.0) · Pipeline status

For general guidance only · Conditions change · Swim at your own risk