O'Neill Slough: toxic algae advisories
O'Neill Slough, San Mateo County. See all San Mateo County waters.
What the state's records say
The state's latest record, from Nov 13, 2017, recommends no advisory.
That reflects what the state knew on that date. It is not a finding that the water is safe now: blooms can return within days, and many are never reported.
Before you go, check the state's official algae page and any signs posted at the water.
Dogs at O'Neill Slough
The state's latest record, from Nov 13, 2017, recommends no advisory. For O'Neill Slough, that is not the same as an all-clear for today. Look at the water before your dog goes in: keep it out of green, blue-green or scummy water and away from mats on the shore.
Reported spots
The state records each report at a spot, such as a beach or a boat ramp. Each spot's latest deciding record:
| Spot | Status |
|---|---|
| O'Neill Slough, San Mateo | The state's latest record, from Nov 13, 2017, recommends no advisory. |
Advisory history
Every advisory record the state has published for O'Neill Slough, newest first. "None" is the state's record that no advisory was recommended on that date. "NA" records do not change a status.
| Date | Spot | State's level | Notes |
|---|---|---|---|
| Nov 13, 2017 | O'Neill Slough, San Mateo | None |
Source
Advisory data: California State Water Resources Control Board, Freshwater Harmful Algal Bloom Program, via data.ca.gov (public domain). Advisories are recommendations; reporting is voluntary and incomplete. The state's data. An advisory ends only when the state records a later "None" (no advisory recommended) at the same spot, or an end date. A blank end date is unknown.