Blue-Green Algae

Southern Oregon & Rogue Basin Water Advisories

Cyanobacteria (harmful algal bloom) health advisories for the lakes and reservoirs a Rogue-area angler is likely to fish, filtered from the Oregon Health Authority advisory dataset. The mainstem Rogue is rarely listed; the stillwaters are what to watch in summer.

Waters Monitored 12
Active Now 4
Last Checked Sep 7, 2026 8:17 PM

Status Levels

Advisory — avoid all water contact Precaution — visible bloom or detection; use caution Recently lifted Tested clear (below health threshold)

Active Advisories & Precautions

Fishing is usually still allowed — avoid visible scum, keep pets and kids out of it, and skin and gut fish before eating.

Agate Reservoir

Precaution
Jackson County Microcystin: 2.46 ug/L Issued Aug 21, 2026

Precaution issued due to cyanobacteria detection and visible bloom (see image below).

Diamond Lake

Precaution
Douglas County Issued Aug 21, 2026

Precaution issued due to visible bloom (see image below).

Lemolo Lake

Precaution
Douglas County Issued Aug 21, 2026

Precaution issued due to visible bloom (see image below).

Hyatt Lake

Precaution
Jackson County Anatoxin-A: 0.54 ug/L Issued Jun 3, 2026

Precaution issued due to visible bloom (see image below).

Recently Lifted

Lost Creek Lake

Lifted

Initial precaution was issued 5/22 due to visible bloom. Non-detect again confirmed on 6/30.

Tested Clear

Sampled and below the health threshold as of the issue date. Conditions still change — use your eyes.

Applegate Lake Jun 30, 2026
Emigrant Lake Jun 30, 2026
Fish lake Jun 30, 2026
Fourmile Lake Jun 30, 2026
Galesville Reservoir Jun 30, 2026
Howard Prairie Lake Jun 30, 2026
Willow Lake Jun 30, 2026

Source: Oregon Health Authority harmful algae bloom advisories, checked Sep 7, 2026 8:17 PM. OHA is the issuing authority — this is a filtered view for Rogue basin waters, not a substitute for checking OHA before you go. Advisories can be issued or lifted between our checks.


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