“We’ve known for a long time that after a lot of pumping, you start running out of groundwater,” said Ryan Smith, a doctoral candidate in geophysics at Stanford and lead author of the study. “We hadn’t really thought that pumping too much water would cause water quality issues.
While arsenic is a naturally occurring element often present at low levels in groundwater, at high doses it can be toxic. Consuming too much of it, through tainted water supplies or agricultural products, has been linked to cancer, heart disease, skin lesions, and liver and kidney damage.,," -- Kurtis Alexander, SF Chronicle, June 5, 2018
In the rapidly moving environmental disaster called the San Joaquin Valley, constantly spurred on to new depths of eco-atrocity by the government-farming, mega-growers of Westlands Water District and the Friant Water Users Authority, a new poison joins the ranks of the heavy metals that have caused such death and deformity to birds, cattle and human babies in the Kesterson National Wildlife Refuge and surrounding areas that is was front-page news throughout the state and nation and the government was forced by the public to appear to be saying No to west side agribusiness for once.
Of course, who can blame these corporate yeomen of the earth now that restrictions on their previous overuse of surface water from the Sacramento-San Joaquin Delta and the San Joaquin River caused them (they could do nothing else but maximize their profits!) to plant permanent crops, which required water not guaranteed by Nature or the federal Bureau of Reclamation? So, you see, they just had to pump, and with the largest pumps they could find, in the deepest wells they could dig, while the government passed little laws creating organizations called integrated regional water management groups to create "plans," called, appropriately IRWMPs, pronounced "ear-wimps."
And so the government and the university scientists it funds will do research, following the most exact, pure scientific methodologies, to prove that the farmers are pumping up more and more poisonous water, which, in the field-draining process, will be concentrated and added to the mix of toxins already in farm sumps, the San Joaquin River and its tributary rivers. Peer-reviewed scientific papers will be published; hearings will be held; the odd editorial will be written.
And then California agribusiness will lavish upon the pathetically corrupt state legislature and Congress the necessary funds to keep up the momentum of environmental destruction of the San Joaquin Valley.-- blj
San Francisco Chronicle
Overpumping of Central Valley groundwater has side effect: too much arsenic
By Kurtis Alexander
The many wells that nourish the farms of the Central Valley are not only pumping so much water from the ground that the land is sinking, they’re creating a dangerous vacuum where arsenic can slip in, new research shows.
Scientists at Stanford University are warning if heavy groundwater pumping continues, water supplies for dozens of communities as well as billions of dollars of irrigated crops are at risk of contamination.
The findings, published Tuesday in the journal Nature Communications, heighten concern about water quality as California’s agricultural belt faces a lingering water shortage even while much of the state has recovered from the recent drought. Both of the problems are greatest in rural parts of the southern San Joaquin Valley, often where poor, farmworker towns can least afford them.
“We’ve known for a long time that after a lot of pumping, you start running out of groundwater,” said Ryan Smith, a doctoral candidate in geophysics at Stanford and lead author of the study. “We hadn’t really thought that pumping too much water would cause water quality issues.”
While arsenic is a naturally occurring element often present at low levels in groundwater, at high doses it can be toxic. Consuming too much of it, through tainted water supplies or agricultural products, has been linked to cancer, heart disease, skin lesions, and liver and kidney damage.
The Stanford researchers found a direct correlation between aquifer contamination and how much the land had sunk due to overpumping. In spots where the ground had dropped more than half an inch, the risk of water being at unsafe arsenic levels doubled or even tripled.
“It’s definitely a big deal,” Smith said. “This is a resource that a lot of people are relying on for their drinking water as well as their livelihoods through the economic value of the crops.”
The researchers drew their conclusions by looking at arsenic concentrations at hundreds of wells over several dry years and comparing the records to satellite measurements of aquifer levels and land subsidence.
Most of the analysis was done in Fresno and Tulare counties, home to nearly 1.5 million people and two of the state’s most productive agricultural regions, where the bulk of California’s almonds, grapes and tomatoes are produced. But contamination because of groundwater overdraft, the researchers said, could happen almost anywhere in the Central Valley.
According to the study, the arsenic is coming from clay deposits beneath the valley floor, which have been carried there in rivers from the High Sierra over millions of years. While the element is normally locked up in the clay, excessive groundwater pumping has reduced the water pressure in the sandy aquifers around the clay, allowing the substance to escape into the groundwater.
“The little clay zones, you can think of as a sponge,” said Scott Fendorf, a professor of earth science at Stanford and a co-author of the study. “Those sponges are dirty water sponges, and the water inside those clay sponges is being held in there from pressure from the outside. When you de-pressure the water outside of the sponge, the sponge lets its water out.”
The result, Fendorf said, is often arsenic levels above the federal standard of 10 parts per billion. Levels in Madera County have been recorded as high as 12 times the limit.
Several communities in the San Joaquin Valley are in similar straits. Some suppliers have faced ongoing fines for arsenic levels in excess of the safety threshold, but in many cases, that’s only made it harder to afford pricey fixes.
The town of Lanare (Fresno County), after years of dealing with contaminated water, went as far as raising money needed to build a treatment plant to remove arsenic. The facility, however, proved too expensive for the mostly farmworker population to pay to operate, and the plant shut down.
“There are many communities in California that are taking a risk every time they take water from the faucet,” said Jenny Rempel, director of education and engagement for the Community Water Center, a Tulare County-based advocacy for clean drinking water. “Communities are unable to get the financing they need to implement solutions.”
Short of getting money necessary for new infrastructure, the Stanford researchers found that aquifer contamination tends to lessen when groundwater overdraft ceases.
However, pressure to pump persists as water demands often outpace what’s available from rivers and reservoirs.
“If we can get our pumping down to more reasonable levels, over time the arsenic levels go back down,” Smith said. “But if we continue with an unsustainable level of pumping, we’re contaminating the aquifer so that we might not be able to use it at some point.”