Executive Summary for March 4th

In this weekly roundup, we analyze key developments in the California drought, including what the latest snow survey numbers mean, and the downside to approaching storms caused by atmospheric rivers. And we look at the drought’s impact on birds, whose wetland habitats are shrinking.

Published on March 4, 2016 Read time Approx. 4 minutes

Snow Survey Report

March 1 marked the year’s third media-oriented snow survey at Phillips Station by Frank Gehrke, chief of the California Cooperative Snow Surveys Program. This month’s snowpack was well below the previous month after a relatively dry and very warm February. Last month the snow water equivalent was 130 percent of the historical average for February.

The Department of Water Resources reported this week that the snowpack statewide had now fallen to 83 percent of average. The water content at the reading site was 27.1 inches (68.8 cm) and the snow was 58.3 inches (148 cm) deep.

“Right now, we’re obviously better than last year but still way below what would be considered adequate for any reasonable level of recovery at this point,” Gehrke said.

Across the state, the readings varied, with the highest water content not surprisingly in the northern Sierra Nevada (89 percent of normal), central Sierra was 85 percent of normal and the southern area came in at 75 percent of normal.

Although the snowpack has decreased since last month, compared to this time last year, the state is in much better shape. The snow depth for March 2015 was 6.5 inches (16.5 cm) and the water content a mere 1 inch (2.5 cm).

It’s also not too late in the season for more wet weather, and March is about to prove that point. The upcoming forecast calls for rain and snow, and the Tahoe area mountains are expected to get three feet of snow in three days.

But wet weather does not mean Californians should be complacent about the drought.

“What should we do? Conservation efforts must remain in place and even expand,” wrote Peter Gleick, president of the Pacific Institute, in the Sacramento Bee. “Education about the need to save water must continue. New financial aid must be made available to rural communities without safe and reliable water and to farmers and cities seeking to modernize water systems. And we must accelerate investments in the treatment and reuse of wastewater, stormwater capture and programs for improving urban and agriculture water-use efficiency.”

Unwelcome Weather Events

After a very dry February, California is expecting a series of storms that will bring rain, wind and snow over the next several weeks. Added to this at times will be an “atmospheric river,” which NASA defines as “narrow jets of very humid air that normally originate thousands of miles off the West Coast, in the warm subtropical Pacific Ocean.”

More wet weather in general is welcome in still drought-parched California. But new research suggests that atmospheric rivers may actually make things worse.

A new study by NASA, UCLA, Scripps Institution of Oceanography and the Earth System Research Laboratory found that these kinds of storms increase the likelihood of “rain-on-snow” events by 2.5 times. If you’re trying to build a snowpack that will melt slowly in late spring and summer months, providing critical water for reservoirs, then rain-on-snow events are bad news.

The study found that while only 17 percent of storms that hit the West Coast are the result of atmospheric rivers, the storms deliver a big punch: 30 to 50 percent of the state’s precipitation and 40 percent of the snowpack. But, they also cause 80 percent of the biggest floods.

“Those events increase flood risks in winter and reduce water availability the following summer,” the report found.

Water availability in summer months is reduced by the rain melting the snowpack. How much that happens depends on the air and rain temperatures. “But the researchers found that, on average, warmer storms generate about a quarter-inch (0.7 centimeter) of snowmelt (i.e. liquid water) for each day of rain, providing 20 percent of the water available for runoff in these events,” the report found. “‘In other words,” as [lead study author Bin] Guan explained, ‘The primary contribution to any flooding still comes from the rainfall, but the melting snow makes things 20 percent worse.’”

Goodbye Wetlands

California’s drought has had far-reaching impacts, and a new story in High Country News explores one of those impacts that often gets overlooked: wetlands. In the last hundred years, we’ve lost 90 percent of California’s wetlands, thanks in large part to development. So what is left has become a precious resource for birds.

It turns out, in the Central Valley, an important habitat for 181 bird species, there are just 19 wetlands that cover 270 square miles. And the drought has further impacted this.

“Over the past five years during the state’s historic drought, those birds have returned, only to find once watery areas no longer suitable for nesting,” High Country News reports. “If dry conditions persist, the little remaining space could disappear.”

Less habitat negatively impacts the breeding for birds and exposes them to more diseases, including avian cholera.

“As the climate changes and habitat continues to decrease, our real fear is that the bird populations already doing badly will dramatically decline, and populations holding steady will also begin to drop off,” Meghan Hertel, director of Audubon California’s wetlands drought monitoring program, told High Country News.

Top image: Frank Gehrke, chief of the California Cooperative Snow Surveys Program for the Department of Water Resources, checks the depth of the snowpack as he conducts the third manual snow survey of the season, at Phillips Station, Calif. on March 1, 2016. The statewide snowpack is now 83 percent of average. (Rich Pedroncelli, Associated Press)

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