River conditions and notices

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Current algae records

Rio Dell · Algal mat alert sign

An algal mat alert is listed for Rio Dell based on a visual finding and testing that detected cyanotoxins.

California State Water Resources Control Board FHABS program · advisory 2026-08-14 · observation 2026-07-23
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South Fork near the confluence · Algal mat alert sign

An algal mat alert is listed near the South Fork confluence based on a visual finding and testing that detected cyanotoxins.

California State Water Resources Control Board FHABS program · advisory 2026-09-03 · observation 2026-08-11
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Eel River near Fortuna · Algal mat alert sign

An algal mat alert is listed near Fortuna based on a visual finding and testing that detected cyanotoxins.

California State Water Resources Control Board FHABS program · advisory 2026-09-03 · observation 2026-08-11
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Myers Flat · Under investigation

A May 21 public report near Myers Flat remains listed as under investigation. It is not a confirmed current site test.

California State Water Resources Control Board FHABS program · advisory 2026-05-29 · observation 2026-05-21
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Humboldt County freshwater · Harmful algae warning

Humboldt County advises visitors to watch for harmful algal blooms, especially in slow or stagnant water. This is regional guidance, not a test of every river spot.

Humboldt County DHHS Environmental Health · advisory 2026-07-24 · observation 2026-07-23
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How these records are used

Official advisory labels remain as issued. A record applies only to its documented geographic scope. Weather and gauge observations do not determine algae or swimming safety, and a missing test is not an all-clear.

The statewide reports system is voluntary and is not a comprehensive testing program.

California HAB response guidance ↗

Live weather and gauges

Weather

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River reading

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Measurement details

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Flow measures how much water passes the gauge. Gauge height is measured from a fixed reference; it is not the depth at your swimming spot.

Access

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