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GOES satellite image of the atmospheric river phenomena from March 20, 2018.

California Funds Atmospheric Rivers Research

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A better understanding and forecasting of atmospheric rivers could improve flood control and water management in California.

The 2019-20 California state budget includes $9.25 million to pay for research into how the state Department of Water Resources can more accurately track the intensity and landfall locations of atmospheric rivers. About half of the state’s annual rainfall and 90 percent of its flooding come from such events.

“Improved forecasting and monitoring of atmospheric river storms would benefit not only California, but the Southwest, in managing our water supply,” said Kelley Gage, director of water resources for the San Diego County Water Authority. “With better forecasting, water managers could also prepare and plan for flooding events caused by the atmospheric rivers.”

The science behind atmospheric rivers

The science behind atmospheric rivers. Graphic: NOAA

Rivers in the sky

Atmospheric rivers are relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics, according to NOAA. When the atmospheric rivers make landfall, they release the water vapor in the form or rain or snow.

“The rivers can stretch from 250 to 370 miles wide and carry a water amount more than 7 times the volume of the Mississippi River,” said Alexi Schnell, water resources specialist with the Water Authority.

The research funds were allocated to the Department of Water Resources to “improve observations, forecasts and decisions in support of atmospheric river precipitation events” as part of the DWR’s Research, Mitigation, and Climate Forecasting Program.

Atmospheric Rivers

Atmospheric Rivers in Water Year 2019. Graphic: Center for Western Weather and Water Extremes

Volatile water resources

A new study led by Scripps Institution of Oceanography at UC San Diego suggests that a new regime of wet and dry extremes is emerging in California. The study shows that the projected increase of extreme precipitation is likely to be caused by streams of moisture in the sky known as atmospheric rivers.

The study was published July 9 in the journal Nature Scientific Reports.

“California already has the most volatile water resources in the country,” according to a news release from Scripps. “Scripps scientists discovered that the state’s precipitation, as it becomes less frequent but preferentially stronger, will vacillate even more wildly between extremes of drought and flooding as a consequence of climate change.”

The federal Bureau of Reclamation, the Southwest Climate Adaptation Science Center, NOAA, the U.S. Geological Survey, and NASA funded the study, “Precipitation regime change in Western North America: The role of Atmospheric Rivers.”

California weather extremes

“As Mediterranean climate regions around the world are becoming more subtropical, the dry season is expanding. California is no exception,” said Alexander Gershunov, a climate scientist at Scripps. “What is exceptional about California is that the heavy precipitation is projected to become more extreme. We knew this from our past work. Now we have identified the mechanism responsible for this bolstering of extremes, and that gives us a more nuanced understanding of what to expect from future hydroclimate and a clearer interpretation of ongoing changes.”

 

Atmospheric Rivers helped California's snowpack in Winter 2018-19.

For the year-to-date 2019, the precipitation total was 19.05 inches, 3.74 inches above average, and the wettest such period in the 125-year record. Graphic: NOAA

Atmospheric Rivers boost snowpack

During the 2018-19 winter, atmospheric river events significantly increased snowpack in the Sierra Nevada and the Rocky Mountains. Both areas are key sources of water supply for the Southwest, including California and San Diego County.

Precipitation in the contiguous U.S. was above average from January to June 2019, according to a NOAA climate report released this week. The report said the 19.05 inches during the six-month period was 3.74 inches above average and the wettest such period in the 125-year record.

The January-to-June 2019 precipitation map showed California’s statewide precipitation was “above average” and “much above average.”

San Diegans attending the Pure Water Day Open House could sample the purified water produced at the North City Water Reclamation Plant's demonstration facility. Photo: City of San Diego

Pure Water Day Delivers Pure Family Fun

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The City of San Diego held its third ‘Pure Water Day’ Open House at the North City Water Reclamation Plant in the Miramar area, inviting residents to enjoy family-friendly activities and learn about the upcoming project construction.

More than 300 community members took tours of the five-step water purification process at the Demonstration Facilities. Photo: City of San Diego

More than 300 people took tours of the five-step water purification process at the demonstration facilities. Photo: City of San Diego

More than 300 people took tours of the five-step water purification process at the Pure Water Demonstration Facility and tasted the purified water produced at the facility following their tour. Residents of University City, Clairemont, and Scripps Ranch learned about Phase 1 of construction scheduled in their neighborhoods.

“We are excited to once again open our doors to the community, and share how we will deliver a new, safe, local source of drinking water for San Diego,” said John Helminski, assistant director of the San Diego Public Utilities Department.

Attendees enjoyed a variety of family-friendly activities at the third annual Pure Water Day. Photo: City of San Diego

Attendees enjoyed a variety of family-friendly activities at the third annual Pure Water Day. Photo: City of San Diego

Pure Water first phase starts construction later this year

Pure Water San Diego is a multi-year phased program using proven technology to clean recycled water to produce safe, high-quality potable water. After construction is completed, the Pure Water Program is expected to provide one-third of the City of San Diego’s water supply by 2035.

The first phase of construction includes the North City Pure Water Facility, new pump stations and pipelines, and upgrades to existing facilities. The North City Pure Water Facility will be constructed on City of San Diego owned property east of Interstate 805 and north of Eastgate Mall, across from the existing North City Water Reclamation Plant.

Purified water produced at the completed plant will be delivered to the Miramar Reservoir, blended with the City of San Diego’s imported and local water sources, and treated again at the existing Miramar Drinking Water Treatment Plant. After this process, the water will be distributed to customers. Construction of Phase 1 is expected to begin later this year and is scheduled for completion in 2023.

Water Authority board chairman Jim Madaffer addresses the National Albondigas Political Society of San Diego about water's importance to the region's economy. Photo: Water Authority Water supply reliability

Madaffer: Collaboration Propels San Diego Water Supply Reliability

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As the San Diego County Water Authority celebrates its 75th anniversary this month, Board Chair Jim Madaffer offered a fresh vision of the region’s water future and outlined new efforts to ensure water supply reliability for generations to come at the National Albondigas Political Society of San Diego meeting in Chula Vista.

Madaffer pointed to the 2003 Quantification Settlement Agreement with the Imperial Irrigation District as an example of the creative thinking and political leadership needed to secure reliable water supplies not only for San Diego County, but across the southwestern U.S by working cooperatively.

“We were able to work out a deal with the Imperial Irrigation District for 200,000 acre-feet of water,” said Madaffer, noting that IID has priority rights to Colorado River water supplies. “How smart to have this insurance policy for the region.”

Madaffer said one of the key efforts ahead is securing storage rights for the San Diego region’s water at Lake Mead, a strategy that could offer benefits to the San Diego region and more broadly across the Southwest by minimizing the chances that Lake Mead will slip in formal shortage status.

Water Authority board chairman Jim Madaffer (right) with John Dadian of the National Albondigas Political Society of San Diego. Photo: Water Authority water supply reliability

Water Authority Board Chair Jim Madaffer (right) with John Dadian of the National Albondigas Political Society of San Diego. Photo: Water Authority

Creative concepts explored to improve water supply reliability

Madaffer also outlined some of the concepts being explored by the Water Authority and its member agencies to improve water supply reliability with more diverse water supply sources, along with engineering and political creative thinking.

Madaffer said the Water Authority’s Board of Directors is considering a study about constructing a regional pipeline system to move the San Diego region’s independent water supplies from the Imperial Valley directly to San Diego. He said the options offer additional advantages to farmers in Imperial County and the Salton Sea.

“I’m a regionalist,” said Madaffer. “I’m interested in what we can do to make sure all of our member agencies are supported, and make sure water delivery works for the entire region.”

Graphic: Water Authority

San Diego is Brought to You by Water

Displaying a chart showing the change in water supply sourcing from 1990 to today, Madaffer asked, “Do we think we can insulate our region from the ravages of drought, so we aren’t depending on pipeline relining and several pipelines delivering imported water?”

He said the region’s approach includes a mix of investments, backed by efforts to use water wisely.

“We’re using less water today with 900,000 more people than we did back in 1990,” said Madaffer, calling it a conservation success story. “All our member agencies, plus each of you in this room, are responsible for helping make it happen.”

Madaffer also touted the region’s innovation culture.  “From Qualcomm to BIOCOM to all of the technology we produce, we are a hotbed of innovation in the region,” he said. “If you remember our drought back in the 1990s, there were states trying to grab our people, saying ‘Hey, work in our state instead, because California is out of water.’ We’ve changed that narrative 100 percent … San Diego is Brought to You by Water.”

A new landmark agreement led by the San Diego County Water Authority will provide regional water solutions which include storing water in Lake Mead. Photo: National Park Service

San Diego County Quality of Life Indicators Mostly Positive in 2018

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A report released today showed improvement in 2018 for the majority of 15 indicators used to measure San Diego County’s quality of life. The Equinox Project Quality of Life Dashboard measures and benchmarks several environmental and economic trends throughout the region.

The analysis highlighted the San Diego County Water Authority for developing water solutions for San Diego and the Southwest using a “portfolio approach.” One of the initiatives under that approach includes efforts to store water in Lake Mead on the Colorado River, which would benefit both San Diego County residents and many other river users.

San Diego County's water supply has diversified significantly over the last couple of decades.. Source: San Diego County Water Authority

San Diego County’s water supply has diversified significantly over the last couple of decades. Source: San Diego County Water Authority

The nonpartisan Equinox Project report is a source of public policy research and analysis to guide policymakers, planners and other officials, said Emily Young, executive director of The Nonprofit Institute at the University of San Diego, where the project is based.

Water use increased in 2018

“There’s no one indicator when you’re talking our quality of life in the San Diego region,” Young said. “And in fact, the whole point is all of these things are connected. If you’re talking about air quality, you really can’t talk about that if you’re not also talking about our transportation systems and the pollution generated from them.

“Whether we’re looking at an issue like water, which is very precious to the San Diego region, or other issues around transportation or housing, all of these are things that we’re measuring our progress on,” said Young.

Per capita water use in San Diego County

*This data includes agricultural water use served by local water agencies.
In 2018, National City had the lowest municipal and industrial (M&I) water use at 78 gallons per capita daily. Yuima’s high per capita M&I potable water use occurs because a large amount of water used for horticultural irrigation is classified as M&I, and the district services a small population (less than 2,000 people). Data Source: San Diego County Water Authority

Measuring quality of life

Six of the 15 indicators received a “thumbs-up” in the report, including air quality, electricity use and renewable energy. Four indicators, including water use, received a “thumbs-down.”

“Daily residential water consumption in San Diego County increased by 8.3% from 84 gallons per capita in 2017 to 91 gallons in 2018,” according to the report. “Water use has increased since the statewide water restrictions were lifted in 2017, though below pre-drought levels.”

*Sweetwater Authority is comprised of the South Bay Irrigation District and National City. The dataset excludes the City of Del Mar, the City of Oceanside, Camp Pendleton Marine Corps Base and the Yuima Municipal Water District.
In Q4 of 2018, residents in the Sweetwater Authority area (National City and South Bay) had the lowest residential water use in San Diego County. Santa Fe Irrigation District used 363 gallons per capita/day, the most water per capita in San Diego County. Data Source: State Water Resources Control Board, Urban Water Supplier Report, 2019

Water use lower in 2019

Despite the slight increase in water use during 2018, residents continue to conserve compared to previous years.

“While extreme dry conditions contributed to increased residential water use in 2018, per capita water use was still lower than historical, pre-drought levels,” said Alexi Schnell, water resources specialist with the Water Authority. “Water use to date in 2019, a much wetter year, has been consistently lower than in 2018.

“There will always be fluctuations based on weather and other factors, but the San Diego region continues to embrace water-use efficiency, and per capita water use in the region is not forecasted to return to pre-drought levels for the foreseeable future,” Schnell added.

The report noted that “the San Diego region is making significant commitments to water efficiency and recycling” and has diversified local supply with the Claude “Bud” Lewis Desalination Plant in Carlsbad, the nation’s largest seawater desalination plant.

The San Diego County Water Authority has a long history of supporting a portfolio approach to address mounting environmental and water supply challenges in the Bay-Delta, the hub of the State Water Project. Photo: California DWR

Water Authority Invites Gov. Newsom to Tour Facilities, Praises Portfolio Approach to Water Security

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The San Diego County Water Authority today praised Gov. Gavin Newsom for taking a proactive, far-sighted approach to water supply planning for California, and pledged to help the governor advance his portfolio strategy for water security in the face of a changing climate.

In a letter to Newsom, Water Authority Board Chair Jim Madaffer thanked the governor for the “wisdom and leadership” shown last week with the issuance of Executive Order N-10-19 and invited the governor to tour San Diego County’s cutting-edge water facilities.

Newsom’s order directed his administration to “identify and assess a suite of complementary actions to ensure safe and resilient water supplies, flood protection and healthy waterways for the state’s communities, economy and environment.” Newsom then directed state agencies to scrap Brown Administration plans for a $18 billion two-tunnel system for moving water through the Sacramento-San Joaquin Bay-Delta in favor of a one-tunnel system.

“We congratulate you on Executive Order N-10-19 and stand ready to support you and work with other stakeholders to ensure its success,” Madaffer wrote to Newsom. “If state and federal dollars are prioritized to support local, integrated planning solutions, we will realize the State’s 2009 promise to reduce demand on the Bay-Delta.”

Portfolio Planning For Water Security

The Water Authority has a long history of both portfolio planning for the region’s water security and supporting a portfolio approach to address mounting environmental and water supply challenges in the Bay-Delta, the hub of the State Water Project.

“Almost two decades ago, the Water Authority’s Board of Directors chose to take affirmative steps to change what had been an ‘end-of-the-pipeline’ mentality, when our agency relied greatly on water imported from the Bay-Delta,” Madaffer said. “In other words, we embraced then the intent of Executive Order N-10-19, and believe our experience is proof that it can be done.”

In 2013, the Water Authority joined several Southern and Northern California water districts, Natural Resources Defense Council, and other conservation groups in proposing a Portfolio Alternative for the Bay-Delta. That proposal included a single tunnel, increasing water storage south of the Bay-Delta, and significant investments in local and regional water supplies.

That approach didn’t gain enough support in the Brown administration, but it aligns closely with Gov. Newsom’s executive order.

Strategic partnerships

The portfolio approach also aligns with what history has shown to be a highly successful strategy in San Diego County, which relied almost entirely on water supplies controlled by external interests in 1991.

“After suffering the devastating impacts of drought and water shortages that year, our community got to work, determined to gain local control over the cost and reliability of our water,” Madaffer said. “Since then, the Water Authority and its member agencies have invested over $2 billion in local projects.”

Those investments include:

  • The nation’s largest agricultural water conservation and transfer agreement with the Imperial Irrigation District
  • The first new dam in the county in more than 50 years at Olivenhain Reservoir
  • The nation’s largest seawater desalination plant, producing up to 56,000 acre-feet of water annually
  • The raising of San Vicente Dam, more than doubling its capacity
  • Water-use efficiency programs that have helped reduce per capita potable water use by more than 40 percent in San Diego County

“Every dollar of investment the Water Authority has made represents a commensurate reduction of take on the Bay-Delta,” said Madaffer’s letter.

He noted that the Water Authority and its member agencies are still at work, with more local projects on the drawing board, including a Pure Water potable reuse program being developed by the City of San Diego and the East County Advanced Water Purification Project.

“We are also continuing to plan for the future, with an upcoming study that will explore water, conveyance, storage, treatment and energy opportunities with strategic partners in Imperial Valley, Mexico and across the Southwest,” Madaffer said. “This initiative is the next generation of the Water Authority’s evolution, and the ‘poster child’ for your Portfolio Alternative.”

The Water Authority is looking at new integrated solutions such as a storage account in Lake Mead that would help raise water levels in the drought-stressed reservoir and avoid formal shortage conditions that could hamper water deliveries across the Southwest. The Water Authority also is supporting a Salton Sea action plan that will protect both the environment and public health; binational opportunities with Mexico; and clean energy generation.

Yuima is among the smallest water districts in the San Diego County metropolitan area, covering 13,460 acres. Its 10 largest water users are all agricultural customers, consuming approximately 70 percent of total district water deliveries annually. Photo: Yuima Municipal Water District Pauma Valley

Cooperation Preserves Pauma Valley Groundwater

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Instead of waiting for Yuima Valley’s precious groundwater supplies to dry up, the Yuima Municipal Water District and local farmers are working cooperatively to create a sustainable long-term strategy for maintaining the region’s economy and quality of life by proactively managing the valley’s aquifer.

To the east in Borrego Springs, the chronically water-short community offers a warning about over-tapping groundwater. Borrego Springs expects to face a 75 percent reduction in water supplies by 2040. The current plan is to let 3,800 acres of agriculture go fallow because farms use 80 percent of the community’s groundwater.

Yuima farmers also have relied on groundwater supplies for decades. Crops such as citrus and avocado flourish in the valley, nestled between Palomar Mountain and Valley Center.

But Yuima farmers want a different kind of future than they see unfolding in other groundwater-dependent areas of arid West.

Working with growers to sustain agriculture

The Yuima Municipal Water District worked with farmers to find realistic, reliable, cost-effective strategies for his customers to keep their farms flourishing without 100 percent reliance on groundwater. Photo: Yuima Municipal Water District

The Yuima Municipal Water District worked with farmers to find realistic, reliable, cost-effective strategies for customers to keep their farms flourishing without 100 percent reliance on groundwater. Photo: Yuima Municipal Water District

Richard Williamson, general manager of the Yuima water district, is working with growers to sustain production and avoid groundwater depletion. When groundwater is pumped faster than it’s recharged, negative effects include reduced water quality, reduced surface water supplies, and land subsidence (or sinking).

“What we’ve tried to do is work on a program encouraging farmers to join our system,” Williamson said. “Many have been pumping wells on their property, and they know it will be curtailed in the future due to new laws protecting groundwater. They need to look to imported water to make up the difference.”

Yuima is among the smallest water districts in the region, covering 13,460 acres. Its 10 largest water users are all agricultural customers, consuming approximately 70 percent of total district water deliveries annually.

Facing increasing state regulations and increasingly hot summers, Williamson worked with farmers to find realistic, reliable, cost-effective strategies for his customers to keep their farms flourishing without 100 percent reliance on groundwater. Adopting a rate structure giving farmers lower pricing in exchange for flexible reliability is the key. The strategy allows the district to slow water deliveries to agricultural customers when imported water supplies are in high demand, similar to power companies offering reduced rates for interruptible service.

“There was a fair amount of discussion and education,” said Williamson. “Farming interests knew they had to come up with an alternative source of water to replace what they might not have in the future. They know it doesn’t serve anyone to draw the system down to nothing. They can look across this valley. All you see is green, citrus and horticulture being raised.”

Yuima agricultural water users try new program

Pauma Valley’s largest agricultural water user and a large avocado farm were the first to sign on. “It was a win-win situation,” said Williamson, “They still pump groundwater, but not as much as they used to. It will help everyone under the new groundwater regulations. Knowing it’s always available, they can set their watering patterns to meet the best efficiency from their water dollars as they possibly can.”

Now Yuima MWD is working to offer imported water supplies through the new program to additional farms by increasing system capacity.

“We currently have projects under way that will double our amount of imported water coming into the district,” said Williamson. “That will be done by 2020, so at that point it will coincide with these new regulations in place. We want to be ready with other agriculture interests. They are under the gun and need alternative sources of water.”

Williamson said so far, Yuima hasn’t faced water supply interruptions. “Because Pauma Valley is such a close-knit community, we will call our biggest users and warn them, ‘Things are a little tight, can you water at night or cut back watering time a little bit to get through this crunch?’ Everyone has been extremely cooperative with this idea.”

Williamson says the goal for his district is to remove the supply interruption provisions completely when capacity upgrades are completed in 2020.

“This valley is all about two things: agriculture, and Indian gaming. The tribes have indicated they don’t want to see agriculture hurt here. They feel it creates a really nice environment,” Williamson said. “This district takes a lot of pride being part of that environment. We want to be a positive influence, rather than wearing a black hat.”

 

 

 

A new landmark agreement led by the San Diego County Water Authority will provide regional water solutions which include storing water in Lake Mead. Photo: National Park Service

OPINION: San Diego Is Ready For Some Big Water Solutions

/in , /by /San Diego Union-Tribuneby Jim Madaffer

Back in the early 1990s — near the start of my career at San Diego City Hall — the San Diego County Water Authority launched a historic effort to sustain the region’s economy and quality of life by diversifying our water supplies so that we didn’t depend on one source for 95 percent of our water. That effort took many forms, many billions of dollars and more than two decades — but it paid off in spades. Even though we are at the literal end of the pipeline, today we have among the most diversified and secure water supply systems anywhere.

Full story here: https://bit.ly/2VDRBE7

 

 

 

Full Story
As a result of the atmospheric river weather phenomenon, California has experienced higher than average rainfall in water year 2019. Graphic: National Weather Service

Atmospheric Rivers Benefit State, Regional Water Supply

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Atmospheric river events in late January and in February have significantly increased snowpack in the Sierra Nevada and the Rocky Mountains, key sources of water supply for the state and San Diego County.

“We’re thrilled by the amount of precipitation – rain and snow – in San Diego County, the Sierra and the Rockies,” said Dana Friehauf, a resource manager with the San Diego County Water Authority.

The statewide Sierra Nevada snowpack was 151 percent of normal at 104 reporting stations for February 27, according to the California Department of Water Resources. The Rockies have received significant snowfall, which will feed the Colorado River, a source of water supply for the Water Authority. The amount of precipitation in most of the Rocky Mountain region, has ranged from 100 to 150 percent for Water Year 2019 through February 25, according to data from the Natural Resources Conservation Service. The percentage is based on the median between 1981 and 2010.

As a result of the atmospheric river weather phenomenon, California has experienced higher than average rainfall in water year 2019. Graphic: National Weather Service

As a result of the atmospheric river weather phenomenon, California has experienced higher than average rainfall in water year 2019. Graphic: National Weather Service

Record rainfall recorded in San Diego

Locally, a bountiful February has helped make Water Year 2019 one of the wettest on record at Lindbergh Field. Preliminary data from the National Weather Service indicates 10.62 inches of precipitation at the San Diego International Airport, with 3.42 inches coming so far in February 2019.

The Weather Service report issued Feb. 24 also shows that last year at this time, just 1.91 inches of precipitation had been recorded at the airport (for Water Year 2018).

In fact, Water Year 2018 (October 1 – September 30) was the second-driest on record since 1850 at Lindbergh Field, with just 3.3 inches of rain, or 32 percent of the long-term average.

Friehauf reminds San Diegans that even in years such as this, when rainfall is plentiful, that water-use efficiency remains a way of life. For instance, each rainstorm is an opportunity to turn off irrigation systems for days or even weeks at a time. She also suggests residents use rain barrels to collect or “harvest” water that can be used later, when the weather is drier.

Capturing the water from gutters and downspouts also reduces the amount of water flowing into storm drains. Homeowners can get rebates on residential rain barrels. Find details on rain barrel rebates here.

 

 

 

 

 

A snow-covered Sierra Nevada Mountain peak to the northwest from the Phillips Station meadow season. Photo: Dale Kolke / California Department of Water Resources snowmelt

Report: Shorter Winters Could Impact Snowpack and Water Supply

/in , /by by Water News Network

New research shows shorter periods of winter weather are altering snowpack melt times, with potentially significant implications for water management and wildfires.

Associate Professor Amato Evan at UC San Diego’s Scripps Institution of Oceanography analyzed snowpack data from 1982 through 2017, publishing his analysis in the December Journal of Applied Meteorology and Climatology, and presenting his findings at the American Geophysical Union Fall Meeting in Washington, D.C.

Evan found no decline in snowfall totals overall, but he discovered snow in mountainous regions is disappearing earlier in the year – in line with earlier projections and modeling. California and other western states rely heavily on snowfall and snowpack for water. When the snowpack melts, it fills reservoirs, a vital resource for cities and farms.

If snowmelt occurs more quickly than normal, it could result in reservoirs filling earlier in the winter or spring. If that dynamic isn’t managed correctly, it could result in losing water supply when the reservoirs overflow. Evan noted California would be among the most-affected states.

Investments buffer San Diego region

Three decades of investments to diversify the San Diego region’s water supply sources with seawater desalination, recycled water and other supplies have lessened the local impact of snowpack variations, said Dana Friehauf, water resources manager for the San Diego County Water Authority. The San Diego region relies on snowmelt in the Rockies and the Sierra Nevada, along with a variety of local water resources. In addition, the Water Authority has expanded local water storage by raising San Vicente Dam and more than doubling the reservoir’s capacity. That allows the region to hold more imported supplies during wet years to prepare for dry ones.

“By increasing water-use efficiency and investing in drought-resilient supplies and local storage, the San Diego region is less susceptible to changes in snowmelt,” said Friehauf. “But climatic shifts likely will be an important factor in water management across the West for years to come.”

Researcher observes winter weather declines

Evan used data for his research collected from a network of over 400 snow telemetry sensors across the western U.S. The sensors compress and expand as snow falls and melts, measuring the weight of the snowpack throughout the season. Evan developed a mathematical expression he could apply to the observations which can identify trends in snowpack variations over the course of the winter season.

Evan found two key changes in mountain snowpack consistent across the western U.S. First, warmer fall and spring seasons are “squeezing” winters, making them shorter from a weather perspective.

Second, higher elevations are showing snowpack characteristics normally found at lower altitudes, with a gradual build up and gradual decline. This translates into less snow and earlier melts. While this has been shown in climate model simulations, the Scripps study is the first time it has been observed. Evan’s findings are consistent with numerous other methods of measuring changes in the seasons.

“The power of this work was the ability to examine how and why snowpack is changing throughout the year,” Evan said in a Scripps news release. “In terms of freshwater in the West, the total amount of snow we receive during the year is important, but how long into the spring that snow stays frozen up in the mountains is also critical.”

The Scripps research was supported by funding from the Climate Program Office at the National Oceanic and Atmospheric Administration.

The California Department of Water Resources conducted the second snow survey of the 2019 season at Phillips Station in the Sierra Nevada Mountains. The survey site is approximately 90 miles east of Sacramento in El Dorado County. Photo: Florence Low / California Department of Water Resources.

Mid-Winter Storms Drench California, Boost Sierra Snowpack

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A remarkable series of winter storms in January and early February has doubled the Sierra Nevada snowpack and recharged reservoirs across the state of California. With more rain and snow in the forecast, California’s water supply picture is far better than it was a year ago, when San Diego received the second-lowest amount of rainfall on record since 1850.

In San Diego County, Lindbergh Field has recorded more than nine inches of rain since October 1, which is nearly the average annual rainfall of 10.33 inches, according to the National Weather Service. More storms are on the way: NWS has forecast more showers in the next few weeks.

Some of the wettest local spots include Mt. Woodson, which received 4.34 inches of rain in the past five days, Lower Oat Flats with 4.08 inches, Rainbow Camp with 3.6 inches, and Fallbrook and Bonsall each with 3.41 inches.

Local rainfall is important, because it allows residents and farmers to reduce or eliminate irrigation for weeks or months at time while Mother Nature does the work. In addition, local surface water meets about 10 percent of San Diego’s annual water needs. From a supply perspective, it is much more important snowpacks continue to grow in the Rocky Mountains and the Sierra Nevada.

Water conditions far better than 2018

Surveyors with the California Department of Water Resources recorded 50 inches of snow and a “snow water equivalent” of 18 inches on January 31 at Phillips Station, where DWR has conducted manual snow surveys for decades.

This was the second of five snow surveys planned for this winter. More than 50 agencies at the local, state and federal levels collaborate on the Cooperative Snow Surveys Program to collect snow data from more than 300 locations statewide each year. Results from these surveys are crucial to water management in California.

The most recent survey at Phillips Station showed the snowpack as 98 percent of average to date – just shy of the statewide average. By comparison, on February 1, 2018, measurements at Phillips Station showed a snow water equivalent of 2.6 inches – just 14 percent of the early-February average. Snow water equivalent is a standard metric of how much water is held in snow.

In the Upper Colorado River Basin, conditions are slightly better than they are in California – a good sign for a region that has suffered nearly two decades of drought. Precipitation and snow water equivalent were both at 105 percent of average at the end of January.

No shortages are expected on the Colorado River system in 2019, though long-term drought conditions continue to be a concern across the Southwest.

San Diego well-positioned to meet regional water demands

The National Weather Service reports that between Oct. 1, 2018, and Feb. 6, 2019, San Diego County received more than nine inches of rain at Lindbergh Field, which was 165 percent of normal, and more than 11 inches of rain at Ramona Airport, which was 142 percent of normal.

“This winter is shaping up nicely,” said Jeff Stephenson, a principal water resources specialist at the San Diego County Water Authority. “A well-timed string of storms and cooler temperatures is allowing us to leave water in storage for use during the dry summer months – and it’s important that everyone continue to leave off their irrigation systems while there’s plenty of water in the soil.”

No matter how the winter plays out, the Water Authority and its 24 member agencies have enough water to meet regional water demands for the foreseeable future. This is made possible by a combination of investments in drought-resilient resources, including the Claude “Bud” Lewis Carlsbad Desalination Plant, conserved agricultural water transfers and continued water-use efficiency measures.