Drought recovery may take until 2020

Paul Mann
Mad River Union

HUMBOLDT – Although Ruth Lake is sparing Humboldt County the worst of the historic drought, the recovery of the rest of the North Coast and the state as a whole may take until 2020, UCLA scientists say.

The fiendish dry spell, now in its fifth year, is the worst since 800 AD.

Currently Ruth Lake in southern Trinity County is at a reassuring 94 percent of capacity. It is fully capable of serving Arcata, Eureka, McKinleyville and the greater Humboldt Bay area in the regional water district.

But the UCLA findings highlight that the rest of the North Coast and much of the state are considerably less fortunate than Humboldt.   

Trinity Lake is at only 53 percent of capacity when historically it is at 62 percent, according to the latest data gathered by the California Department of Water Resources.

As of late June, the Trinity’s average snow water equivalent was a skimpy half inch when it should be two inches. Snow water equivalent means the volume of water that would be released if the snow melted all at once.

“For sure the drought is not over,” said water resources spokesperson Doug Carlson in an interview late last week.

The new UCLA analysis explicitly warns against reports “in the popular media” about El Niño easing the drought, “if not being a ‘drought buster’.” The predictability of snow water equivalents in the Sierra Nevada based on El Niño analyses is limited, the study cautions.

This year’s El Niño, which refers to the warming temperatures and heightened rainfall from cyclical ocean-atmosphere interaction, certainly was a help, Carlson said. “The good rain in the north gave us a lot of runoff into the reservoirs.”

Yet with the drought’s fifth year in process, the ground is so dry that the runoff from the snowpack was definitely less than normal, he underscored. “It wasn’t a bonanza.”

The UCLA research analyzes the extreme 2015 snowpack deficit in the Sierra Nevada. There is less than a seven percent probability that last year’s extreme shortfall will be fully remedied this year, the study forecasts.

The 2015 conditions, occurring on top of three previous drought years, inflicted the worst multiyear snowpack shortfall spanning the 65  years surveyed. University scientists based their conclusions on state-of-the-art snow re-analysis of middle elevations, supported by decades of NASA (Landsat) satellite imagery and historical snowpack data collected since 1951 by the California Cooperative Snow Survey.

Another crucial point is that although most drought outbreaks during the last 65 years ended in one year, more longer-term recoveries may be in store. If ongoing climate change harbors more frequent droughts that coincide with higher temperatures, “there is potential for increased likelihood of large drought deficits that will lead to multiyear recoveries,” the UCLA scientists wrote.      

Snowmelt provides more than 70 percent of total stream flow. The record drought has caused not only critically reduced flow, but also acute water shortages in some regions, groundwater overdrafts and enhanced wildfire risks. (Lightning caused the Klamath National Forest Pony Fire near Happy Camp that broke out June 7, not drought conditions, said Ian Shackleford of the U.S. Forestry Service office in Yreka. Nor did the drought worsen the fire.)

The return to pre-drought levels may take four years or more, despite the historically strong El Niño cycle. The National Weather Service declared on June 9 that the current cycle had dissipated.

The UCLA analysis calculated the probabilities of snowpack recuperation going out two, three, four and five years beyond 2015:

• Year two - 24.9 percent

• Year three - 44.1 percent

• Year four - 61.3 percent

• Year five - 73.9 percent

Recoveries could stretch out if the current drought is part of a yet longer-term phenomenon.

Notably, however, the recovery times might shrink if snow water equivalents are shored up and if more positive underlying trends turn up.

Either way, Business Manager John Friedenbach of the Humboldt Bay Municipal Water District is optimistic about the near term locally. Ruth Lake’s current level of 94 percent of capacity is normal for water releases, and the lake has filled every year since 1976, he said late last week.

“We keep a watch on it and if history is an indicator, we’re confident the lake will fill again and we have an adequate supply not only for now, but for the next few years,” he said.

The UCLA research is posted online in the journal of the American Geophysical Union, the Geographical Research Letters. Six researchers contributed to the analysis, which can be downloaded from onlinelibrary.wiley.com/doi/10.1002/2016GL068520/full.


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