Beneficial for Drought, Contributing Fuel for Wildfires – Reuters

By Daniel Trotta

The atmospheric river currently impacting California presents a dual challenge: it alleviates drought conditions and supports struggling fish populations while also fostering vegetation growth that could heighten wildfire risks in the future.

Here’s an overview of the situation:

Current Precipitation Levels

Following years of severe drought, California is expected to experience its second consecutive wet year, albeit not to the extreme levels seen last year. The state’s water year spans from October to September, with the bulk of annual rainfall typically arriving by April 1.

As of recently, Northern California’s precipitation for this year stood at approximately 85% of its historical average, according to Jay Lund, vice director for the Center for Watershed Sciences at UC Davis. In contrast, Southern California’s agricultural San Joaquin Valley recorded only 65% of its historical average. Lund noted that true assessments of rainfall for the year will become clearer by late March.

Water Resource Management

While rain is preferable to drought for managing California’s water resources, the distribution of rain is crucial. The ongoing storms primarily affect Southern California, which lacks adequate storage capacity compared to the northern regions and struggles to capture stormwater before it flows into the ocean. Consequently, while reservoirs across the state are generally at or above historical averages, they are not reaching the same levels seen during last year’s rainfall events.

“We can’t control where atmospheric rivers go; we can only work with what we have,” stated Jay Famiglietti, a hydrologist at Arizona State University’s Global Futures Laboratory.

Wildfire Preparedness

The added moisture benefits wildfire resistance; however, it also leads to increased growth of grasses and brush, which can act as kindling when dry weather returns. "Those green hillsides in July and August will eventually dry out, creating conditions for rapid fire growth,” explained Nick Schuler, a spokesperson for the California Department of Forestry and Fire Protection.

Historically, wildfires in California occur from April to October, with heightened activity during the hot, dry Santa Ana winds in October and November. The state has shifted to year-round fire preparedness, especially following the severe wildfires of 2020. Despite significant rainfall this year, California reported 29 brush fires in just one week.

Benefits for Fish Species

For endangered and threatened species like the Chinook salmon, this rainfall is overwhelmingly positive. When reservoirs are full or overflowing, water is released from dams to replenish rivers, streams, and floodplains—essential habitats for these fish.

Consecutive wet years are crucial for aquatic ecosystems. Should California experience average rainfall next year, the benefits could extend to salmon populations, many of which hatch in upstream freshwater, migrate to the ocean, and return to spawn.

“Just as three years of drought can severely impact fish populations, a series of favorable water years could significantly aid in recovery,” remarked Carson Jeffres, a senior researcher at the Center for Watershed Sciences at UC Davis.