River updates

Short, dated summaries from official public sources.

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

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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