• Southern California received significant rainfall that aids firefighting efforts but also increases risks of mudslides and toxic ash runoff.
• Flood watches remain in effect for several burn areas around Los Angeles, particularly the Pacific Palisades, Altadena, and Castaic Lake.
• The Palisades Fire, which destroyed thousands of homes, is reported to be 90% contained, while associated wildfires are nearing full containment.
• Officials warn of the dangers posed by toxic ash runoff, which is a mixture of harmful materials like pesticides and plastics.
• Residents are advised to take precautions while cleaning up, as the rain may exacerbate post-fire debris flow conditions.

Southern California has experienced a surge of rain that, while providing much-needed assistance to firefighters battling recent wildfires, has also raised significant concerns regarding hazardous mudslides and toxic ash runoff from the burn areas. Following weeks of dry and windy conditions, the rain over this past weekend has been welcomed by firefighting crews but comes with its own set of dangers, particularly for areas affected by the Palisades Fire, which has been a focal point of the wildfires.

According to meteorologist Joe Sirard from the National Weather Service, “All these fresh burns are very susceptible to rapid runoff.” This means that even a slight amount of rainfall can trigger mud and debris flows, increasing the risk of flooding in the already compromised areas. Flood watches remain active in several regions, including around Altadena and Castaic Lake through the early week.

The Palisades Fire, which has left substantial destruction and at least 11 fatalities, reached up to 90% containment as of Sunday. Meanwhile, the Eaton Fire and the Hughes Fire are nearing complete containment.

Despite the firefighting progress, environmental alarms have been raised concerning the fallout from the rain that leaves toxic ash. Officials stressed that the ash contains harmful materials including pesticides, lead, and even remnants of incinerated electronics and household items which pose severe health risks. This situation has necessitated emergency orders from Los Angeles Mayor Karen Bass to expedite cleanup operations and infrastructure adjustments to mitigate potential flooding in fire-stricken areas.

As warnings of mudflows and debris flows continue, experts recall the catastrophic mudslides that struck Montecito in 2018 following heavy rains on exposed, burn-scarred landscapes. In light of these events, residents are advised to remain vigilant and to wear protective gear while undertaking cleanup efforts in the volatile aftermath of the wildfires. The rain is seen as a double-edged sword, bringing hope against the flames while simultaneously posing a new set of challenges for recovery in a region already grappling with a history of severe drought and devastating wildfires.

For further details, you can read more at The Guardian.