47 solar-powered water-level sensors and public USGS/HCFCD stream gauges sit at bayous, ditches, and storm drains across Houston, reporting stage height every few minutes.

Readings are pulled every 5 minutes via the USGS Water Services API and normalized against each gauge’s official NWS flood-stage thresholds into a single 0–100% flood-capacity score.

Live NOAA rainfall forecasts are combined with each gauge’s current rate of rise to project which streets are likely to flood in the next 30–60 minutes — before the water arrives.

When a sensor crosses the Watch (60%) or Alert (80%) threshold, BayouWatch identifies every registered address within range of that gauge.

SMS, push, and email alerts are dispatched in English, Spanish, Vietnamese, Chinese, or Arabic based on each resident’s preference — typically under 60 seconds from sensor reading to delivery.

That 30–60 minute head start is enough to move a car, leave a low-lying street, or check on a neighbor — well before county-wide flood warnings would have reached the same household.