Executive Summary for October 28th

In this weekly roundup, we analyze key water developments in California including the winter weather outlook. We also look at a dangerous toxin in San Francisco Bay shellfish and new research on the benefits of fire.

Published on Oct. 28, 2016 Read time Approx. 3 minutes

North-South Weather Divide

California is finally seeing some rain, with Northern California getting the biggest soaking. But it is not necessarily an indicator of what the “rainy” season will bring. In fact, there may be more dry weather ahead for the winter, especially for Southern California.

Writing at the Weather Blog, Daniel Swain of the University of California, Los Angeles noted that we have seen a continued “north-south divide” during the last year, with the northern part of the state receiving the most precipitation and Southern California left high and dry. The Los Angeles Times reported yesterday that during October, Southern California’s precipitation was only 60 percent of average, while California communities north of the Bay Area were at 200-300 percent of average.

Swain writes that a few indicators suggest bad news ahead for hopes of making a dent in the drought, including conditions in the Pacific Ocean that are inching back toward those associated with La Nina.

“The unfavorable state of the tropical Pacific Ocean, plus the high likelihood of persistent warmth yet again this winter, suggests that we’re still likely to be talking about the ‘ongoing California drought’ well into 2017,” wrote Swain.

Toxic Algae in Shellfish

A dangerous toxin, microcystin, produced by freshwater algae found in California lakes and rivers, has now been detected in shellfish in San Francisco Bay, the University of California, Santa Cruz reported this week.

This is likely little surprise to researchers since the toxin has been found throughout the Sacramento-San Joaquin Delta, which feeds into San Francisco Bay. The toxin can be a threat to human health, but the greatest danger is to wildlife – such as sea otters, which eat a lot of shellfish.

“We found that this freshwater toxin accumulates in shellfish, both mussels and oysters, and that in San Francisco Bay, the toxin levels in some mussels exceed the recommended guidelines for consumption by quite a bit,” Raphael Kudela, the Lynn Professor of Ocean Health at U.C. Santa Cruz.

Toxic algae blooms like warm, nutrient-rich water and are thriving with higher temperatures, drought and nutrient pollution.

Researchers Find Ecological Benefits of Fire

Scientists have known for a while that a century of fire suppression in the United States was misguided. Now a new 40-year study in Yosemite helps confirm what managing, rather than suppressing fire, can do for the ecosystem.

Since 1973, 40,000 acres (16,000 hectares) in the Illilouette Creek basin of Yosemite National Park have been managed differently – with little fire suppression and few prescribed burns. And researchers for the University of California, Berkeley just concluded a three-year study of how the management experiment has been going.

They found the area was “more resistant to catastrophic fire, with more diverse vegetation and forest structure and increased water storage, mostly in the form of meadows in areas cleared by fires,” U.C. Berkeley reported.

“When fire is not suppressed, you get all these benefits: increased stream flow, increased downstream water availability, increased soil moisture, which improves habitat for the plants within the watershed,” said Gabrielle Boisramé, a graduate student in U.C. Berkeley’s department of civil and environmental engineering and first author of the study. “And it increases the drought resistance of the remaining trees and also increases the fire resilience because you have created these natural firebreaks.”

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