As an onslaught of storms soaked California with record-breaking rain last winter, Christine Gemperle found herself crisscrossing her almond orchards in knee-high muck boots and a slicker. She was out in the driving rain doing exactly what many farmers were trying to prevent: opening her irrigation gates and letting the flood rush into her orchards. …
For generations, during dry periods, California farmers have pumped water from deep underground to keep their crops hydrated when surface water supplies are scarce. Gemperle is no exception. Like many of her fellow farmers in California’s agricultural Central Valley, in dry years she turns to underground aquifers to irrigate the 135-acre almond farm she runs with her brother in Turlock.
But if farmers are the biggest takers of California’s dwindling groundwater supply, they are also becoming critical players in filling those aquifers back up. This year, Gemperle Orchards joined a growing number of farms helping to replenish overdrawn aquifers by flooding their orchards and fields with excess stormwater during wet seasons and letting it soak into the ground.
Drawing out too much groundwater, or overdrafting, is a serious problem in California. As a result, groundwater sustainability agencies are considering using recycled municipal wastewater to recharge aquifers. In our study, we employ suitability mapping and the models C2VSimFG and Ichnos to identify appropriate areas for managing aquifer recharge with recycled water in California’s Central Valley.
The factors that influence suitability include soil properties, proximity to recycled water sources, and the residence time, or amount of time that recharged water spends underground. There are many suitable areas in the Central Valley that are immediately adjacent to water recycling facilities.
However, adequate supply is an issue in most locations. Roughly half of the groundwater sustainability agencies in critically overdrafted basins of the Central Valley have enough potentially suitable locations to meet their recharge goals, but not all of them have access to enough recycled water.
The methods demonstrated here can serve as tools for agencies considering using recycled water for aquifer recharge.
A ribbon cutting is held by the Fresno Irrigation District for the Savory Pond Expansion project in Fresno, California. The project will capture surface water to recharge the underground aquifer which will improve the drinking water supply for domestic well owners and for residents of Shady Lake Mobile Home Park, a local disadvantage community. Kelly M. Grow / DWR
It was exactly the sort of deluge California groundwater agencies have been counting on to replenish their overworked aquifers.
The start of 2023 brought a parade of torrential Pacific storms to bone dry California. Snow piled up across the Sierra Nevada at a near-record pace while runoff from the foothills gushed into the Central Valley, swelling rivers over their banks and filling seasonal creeks for the first time in half a decade.
Suddenly, water managers and farmers toiling in one of the state’s most groundwater-depleted regions had an opportunity to capture stormwater and bank it underground. Enterprising agencies diverted water from rushing rivers and creeks into manmade recharge basins or intentionally flooded orchards and farmland. Others snagged temporary permits from the state to pull from streams they ordinarily couldn’t touch.
Yet not everyone was able to fully capitalize on Mother Nature’s gift.
At this groundwater recharge FloodMAR site, the pump, left, that drives water through underground pipes connected to one of several outlets, seen beyond the base of the pole on th eleft, in this agricultural field is seen in the Dunnigan area of Yolo Couny, a region that has seen a dramatic amount of rainfall and rising water for the past several days. Photo taken January 18, 2023. Andrew Innerarity / DWR
Winter storms have filled California’s reservoirs and built up a colossal Sierra snowpack that’s nearly twice its normal size for this time of year. But years of dry conditions have created problems far beneath Earth’s surface that aren’t as easily addressed.
Groundwater — found in underground layers containing sand, soil and rock — is crucial for drinking water and sustaining farms. During drought years, 60% of California’s annual water supply comes from groundwater. This water is not easily replenished, especially as many groundwater basins across the state are critically overdrafted.
“Even if we have a substantial wet year, it’ll take many years for basins to fully recover, if at all,” said Paul Gosselin, deputy director of sustainable groundwater management for the California Department of Water Resources.
As the impacts of California’s ongoing drought collide with new groundwater requirements, growers and cities in the San Joaquin Valley are scrambling to find sustainable water supply solutions.
But before the current crisis, Tulare Irrigation District (TID) and the City of Visalia (City) developed a model exchange program that brings as much as 11,000 acre feet a year of highly treated recycled water to growers while providing the City with surface water used for groundwater replenishment.
“The partnership has value beyond the water. We enjoy working with the City of Visalia. We consider them our neighbors, our partners, our friends. And we are lock step in developing sustainability for groundwater,” said Aaron Fukuda, General Manager of TID.
On a small scale, aquifers — subsurface natural basins — have benefitted from man-made recharge for decades. Now, a new Department of Water Resources (DWR) assessment shows how Flood Managed Aquifer Recharge, or Flood-MAR, can help reduce flood risk and boost groundwater supplies across large areas of land.
A climate change problem solver, Flood-MAR collects high flow flood waters from heavy precipitation or snow melt and conveys it downstream. There, the flood waters are spread across the land, creating wetland habitat or irrigating fields while also percolating to aquifers underground. The capturing of flood waters during times of peak flows lessens the risk of major flooding during heavy storms. Some of the water later makes its way back to waterways where it can also support ecosystems and riverine habitat. In partnership with the Merced Irrigation District, Sustainable Conservation, and others, DWR experts analyzed how this would work in the Merced River —a 145-mile-long tributary of the San Joaquin River. The Merced River, which flows from the Sierra Nevada to the San Joaquin Valley, could be much more vulnerable to heavy flooding as storms intensify.
Over 600,000 Californians rely on nitrate-contaminated public supply wells for their household water needs. However, those numbers are even greater as they don’t include the many others who struggle with contaminated groundwater from domestic wells. Balancing long-term groundwater sustainability and water quality will help California weather future droughts, ensure safe drinking water, and support our thriving agricultural community that feeds the nation.
One tool for groundwater sustainability is groundwater recharge, where water is intentionally spread on the ground and allowed to infiltrate into the underlying aquifer. However, there is much concern that groundwater recharge can increase water quality issues, especially when the recharge water is spread upon agricultural lands.
In November of 2021, Sustainable Conservation held a webinar featuring a panel of experts who discussed how California can work to replenish our aquifers while protecting water quality for the health of our communities.
“From afar, the rows of knobby grapevines blend into the landscape of pink-blossomed almond trees and fragrant citrus. But get up close and you’ll see something strange: The trunks of the vines are standing in several inches of glistening, precious water.
These grapes, at the Kearney Agricultural Research Center in California’s San Joaquin Valley, are part of a grand experiment that many hope will help solve the state’s deepening water crisis. Here, in the state that provides some 40 percent of all the fresh produce grown in the United States, a 20-year-long drought has left growers and communities desperately short of water. To make up the persistent shortfall from rain and snow, they are pumping groundwater—and doing so far faster than water can trickle down from the surface to replenish underground aquifers. … ”
Land and waterway managers labored hard over the course of a century to control California’s unruly rivers by building dams and levees to slow and contain their water. Now, farmers, environmentalists and agencies are undoing some of that work as part of an accelerating campaign to restore the state’s major floodplains.
Bringing the San Joaquin Valley’s groundwater basins into balance by the early 2040s is going to be challenging, but two neighboring groundwater sustainability agencies (GSAs) in Madera County are collaborating to move the process forward.
As an onslaught of storms soaked California with record-breaking rain last winter, Christine Gemperle found herself crisscrossing her almond orchards in knee-high muck boots and a slicker. She was out in the driving rain doing exactly what many farmers were trying to prevent: opening her irrigation gates and letting the flood rush into her orchards. …
