Discovery Bay keeps Willow Lake under a harmful-algal-bloom caution

The Town of Discovery Bay is posting a CAUTION harmful algal bloom (HAB) advisory for Willow Lake, based on visual indicators consistent with a bloom. The town’s accessible HAB page does not clearly show a “last updated” timestamp, so check the page before heading out.

If you’re planning to visit the lake—whether for walking, watching wildlife, boating, or letting kids play nearby—treat the CAUTION posting seriously.

What the Town of Discovery Bay is telling residents to do now

For the Willow Lake CAUTION advisory, the Town’s guidance centers on preventing contact with potentially affected water and keeping people (especially children) away from both the shoreline and the water.

• Avoid contact with potentially affected water. Don’t swim, wade, or otherwise get in contact with water that looks like it may be part of a harmful algal bloom.
• Keep children away from the water and the shoreline. Don’t let kids play at the edge of the lake when a bloom is suspected.

Pets and dogs: what residents should prevent

Contra Costa Health’s harmful algal bloom guidance emphasizes that pets—particularly dogs—may be more likely to investigate shorelines and drink lake water. During a CAUTION advisory:

• Keep pets away from the shoreline and the water.
• Don’t let dogs drink from the lake.
• Don’t allow pets to swim or splash in affected areas.

Parents and dog owners can make a quick safety plan: keep kids leashed away from the waterline, supervise closely around the shore, and assume “just a quick drink” isn’t worth the risk if the lake surface looks unusual.

What “CAUTION” means (and what it doesn’t)

Contra Costa Health explains that HAB advisories use risk levels, and CAUTION still means you should reduce exposure. Because visible bloom indicators can be associated with health risk, the practical takeaway is to keep a wider distance and avoid contact—especially for children and animals.

If you see suspicious conditions, report it

If you notice conditions that look consistent with a harmful algal bloom (or worsening conditions), follow the instructions in the Town’s HAB materials and use the state’s harmful algal bloom reporting portal referenced in local guidance.

Since the town’s page may not show a clear last-updated time in the accessible view, it’s also smart to re-check the advisory page if conditions appear to be changing.

State context: how these advisories are communicated

A 2024 press release from the California State Water Resources Control Board provides background on how Discovery Bay HAB advisories are communicated and how blooms are reported. For current conditions, rely on the Town’s posted CAUTION level for Willow Lake.

What to watch next

The key next step for residents is to monitor the Town’s HAB advisory page for Willow Lake. If the posting changes, adjust plans right away—especially for families with kids and pet owners.

Sources

• Town of Discovery Bay — Harmful Algal Bloom (HAB) advisory page
• Contra Costa Health Services — Harmful Algal Blooms (CAUTION/WARNING/DANGER guidance)
• California State Water Resources Control Board — Press release on Discovery Bay HAB (July 9, 2024)