Groundwater pumped from subsided islands back into Delta channels through 200 or more active outfalls can be laden with excess nitrogen transported from island soils, report the authors of a new study.

Groundwater



31
Aug

Groundwater pumped from subsided islands back into Delta channels through 200 or more active outfalls can be laden with excess nitrogen transported from island soils, report the authors of a new study.

The Sacramento-San Joaquin Delta contains more than 50 peat islands. Most have subsided—some as much as three meters — as a result of drainage for farming, and must maintain artificial water tables below the land surface via managed pumping. According to researchers from the University of California at Santa Cruz and the US Geological Survey, these pump stations are an underappreciated source of nutrients in nearby waters, with potentially significant implications for habitat and water quality.   To get a sense of how much nitrogen is leaving the islands and when, the researchers measured monthly discharge along with nutrient and trace element concentrations in drainage from three Delta islands over the course of nearly a year and a half, then...
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25
Oct

Saving Water Under the East Bay

It’s a matter of semantics as to whether the Bay Area ever really left the drought of 2014-2017 before staring down another, more severe one beginning last year. But a huge lesson for our entire state from that “first” water shortage still being learned today is that more attention must be paid to groundwater. That’s true even in the urban East Bay, where the East Bay Municipal Utilities District (EBMUD) and the City of Hayward are developing a plan to ensure continued sustainable use of freshwater sitting beneath the East Bay flats from Richmond to Hayward. In September 2014, Governor Jerry Brown signed into law three bills known as the Sustainable Groundwater Management Act. Among other things, the Act requires...
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17
Jun

Ancient River Channels Could Speed Groundwater Recharge

By the time California finally began regulating groundwater use in 2014, most of the San Joaquin Valley was in critical overdraft. The Public Policy Institute of California estimates that groundwater pumping in the region has exceeded replenishment by an average of 1.8 million acre-feet per year over the last few decades. This imbalance was even worse during our last drought, when overuse shot up to 2.4 million acre-feet per year. Overpumping puts groundwater aquifers at risk of compaction, permanently reducing their water storage capacity and making surface lands sink. Now, however, San Joaquin Valley groundwater managers must find and implement a fix. The state’s Sustainable Groundwater Management Act mandates balancing the region’s pumping with replenishment by 2040. Managed aquifer recharge...
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22
Sep

Small Farmers Shortchanged by SGMA

When governor Jerry Brown signed the Sustainable Groundwater Management Act (SGMA) into law in September 2014, he said that “groundwater management in California is best accomplished locally.” With the first round of plans made available for public comment this year, it appears that, while the state certainly ceded control to local management agencies, those same agencies have prioritized the interests of big agriculture and industry over small farmers and disadvantaged communities. A June 2020 paper from UC Davis published in the international journal Society & Natural Resources, as well as work done by the Fresno nonprofit Leadership Counsel for Justice and Accountability, have shed light on the procedural inequities. During the 2011-16 drought in California, declining rainfall, snowpack, and availability...
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06
Jul

Surface water diversions in California’s Central Valley can be estimated based on readily available climate data, say researchers—a boon to efforts to track groundwater use.

Valley groundwater pumping is calculated as the total water demand minus surface water deliveries. However, today’s water model relies on individually reported diversions across the entire valley, and compiling all these data is a slow process; by the time the numbers are crunched, assessments of groundwater use are already outdated. “It can take years,” says Jordan Goodrich of University of Waikato in New Zealand. “It’s one of the biggest problems we face in tracking the Central Valley water budget.” Overdrafting groundwater can cause subsidence, permanently reducing the storage capacity of aquifers as well as jeopardizing above-ground infrastructure that delivers water and controls flooding. In the March 2020 issue of San Francisco Estuary and Watershed Science, Goodrich and colleagues at Scripps...
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26
Sep

San Joaquin Communities Access Cleaner Water Due to New Legislation

The only water easily available to many low-income inhabitants of the San Joaquin Valley’s smaller, non-incorporated settlements is well water tainted with arsenic and nitrates from surrounding activities. But two state bills ensure that these communities – and everyone else in California – not only have the right to safe, clean, and affordable drinking water, but also get access to public water infrastructure and services as needed. Assembly Bill 2501, approved this fall, “makes sure the state’s consolidation authority can order a city or special district to extend clean drinking water services to people in domestic dwellings,” says Phoebe Seaton of the Leadership Counsel for Justice and Accountability. Advocacy on the part of affected communities, with help from organizations like...
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13
Aug

California’s groundwater faces widespread chromium contamination risk resulting from natural, rather than industrial sources.

Chromium’s toxic form, known as hexavalent chromium, is used in steel manufacturing, leather tanning, and wood treatment; its lethal effects were popularized in the 2000 movie Erin Brockovich. But today transformation of the benign form of chromium naturally found in soils poses the larger risk, according to a recent Stanford University study. Dr. Debra Hausladen and her colleagues used a statewide groundwater database to trace the origin of 90,000 chromium samples, and discovered toxic chromium from natural sources is affecting a much higher population and area in California than exposure from industrial sources. Due to the high occurrence of toxic hexavalent chromium in regions such as Central Valley, the researchers suspect groundwater pumping and other human activities play a role...
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05
Jun

Filling Up on Empty

“We are sucking our aquifers dry,” the headline reads. Could this be a good thing? The bad effects of declining groundwater levels are known: land subsidence, the cost of pumping from deeper wells, the drying up of surface springs and streams. But there is a potential gain as well. Using up one resource, the water stored under the ground, we are creating another: storage space far greater than any conceivable new dam could provide. “Historical overdraft,” writes engineer Jay Lund, “may be an effective means of underground reservoir construction.” If so, we have been building like mad.
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