Shellfish farmers make high-stakes calls on water they don’t control, usually with far less information than the big operators who can afford their own sensors and staff. DataShoal is an attempt to close that gap with data that’s already public. This first version covers three California bays, describing conditions before it ever tries to forecast them. This post covers what’s on the site, what it can and can’t tell you yet, and how to tell us where we’re wrong.
Why three bays
We picked three estuaries that are different enough to be informative and similar enough to be comparable. Humboldt Bay is California’s largest oyster-growing region, a North Coast estuary with a dense network of public monitoring stations. Tomales Bay is the long, narrow Marin County estuary with a tight cluster of shellfish farms and a long history of harmful-algae monitoring. Morro Bay is the small, well-instrumented Central Coast estuary at the southern edge of the project. Each has its own water dynamics, its own freshwater inputs, and its own community of growers and researchers.
Public data only
Everything DataShoal uses is publicly available: NOAA buoys and tide gauges, USGS river-flow gauges, the state’s harmful-algae monitoring program (CalHABMAP), California’s shellfish-lease records, and regional sensor networks that publish their readings openly. There are no private feeds and no logins.
Public data is sometimes noisier, sometimes less timely, and sometimes coarser than what’s behind a paywall. But the upside is that anyone can reproduce or push back on the analysis, and the project doesn’t depend on a single data provider’s goodwill to keep running.
Describe first, forecast next
It would be tempting to skip ahead to forecasts and alerts. Before any prediction is worth shipping, though, the readings that would feed it have to be reliably collected, lined up properly in time and space, and understood in their own right. This first phase is about earning that ground truth: a clear read on what is happening in each bay, with every number traceable back to its source. Once we can answer “what’s been happening, in what order, where, and how confidently,” the forecasting work becomes a much shorter conversation. That is the next step on the roadmap.
What’s on this site
The bay pages are the most concrete part of the project so far. Each one shows every public monitoring station feeding into it for that bay, color-coded by what the station measures, with click-to-popup descriptions of what it does and why it’s in. There’s an optional layer that adds the locations of the bay’s shellfish farms, drawn from the state’s lease records.
The maps show what’s being measured, not the readings themselves. Live readings and alerts are on the roadmap once the basic picture here is solid enough to support them.
Update (2026-09): the weekly State of the Bay report described above is now available by subscription for Humboldt, Tomales, and Morro bays. The sample report shows a full week’s edition; you can get it for your growing area from the DataShoal site.
The blog is the slower half: notes on how we’re building the project, decisions written down before they get forgotten, and occasional close looks at a particular station, season, or piece of data worth pulling apart.
Corrections welcome
If you grow shellfish, sample the water, or research one of these three bays, we’d like to hear from you. Corrections to the data, suggestions for stations we should be tracking that we aren’t, and outright disagreement with the choices behind the maps are all welcome.