Maria Herrera grew up in a farm worker family, moving from Michoacán to Orange Cove when she was three. Like many migrants, the family made a living picking fruit grown in the area’s orchards and fields, be they lemons, tomatoes, oranges or stone fruit.

As she grew older the family moved on to other tiny towns like Cutler, Orosi and Sultana along the foothills in Fresno and Tulare counties, and she joined in the picking on weekends and during summers, plucking olives to collect in buckets and helping in the grape harvest.

But while the Central Valley’s produce grows hearty under the hot sun, the laborers who get the product from orchard to processing plant face an unpleasant runoff from their very livelihood: The local groundwater that provides well water for drinking is heavily contaminated with nitrates, a poisonous byproduct of fertilizers and other agricultural sources.

“When we moved to the area, my parents were forced to buy bottled water,” Herrera said. “Communities that only have access to one or two wells are more impacted than those that can blend water from different wells. These towns are pretty small. You may be driving through and not even realize it.”

Today Herrera is the community outreach coordinator for the Visalia advocacy group Community Water Center. She said Orange Cove eventually turned to the Friant-Kern Canal for drinking water drawn from the Sierra foothills, but many similar towns don’t have access to surface sources and depend wholly on nitrate-fouled wells for what flows from their taps.

In the hope of securing healthy drinking water for all valley residents, the nonprofit educates those in at-risk areas about the health risks of toxic drinking water. Nitrates at 10 mg per liter, or 10 parts per million, can cause blue baby syndrome, where the blood loses some of its capacity to carry oxygen, and appear linked to thyroid illnesses and an increased risk of some cancers.

Unfortunately, typical store-bought filters do not remove nitrates, which are tasteless, odorless and colorless, although reverse-osmosis, distillation and ion-exchange filters get the job done. Homes can install point-of-entry systems. Cities can dilute the contaminants with their range of wells; Fresno has 250.

The Community Water Center also supports legislation that seeks to establish a “human right to water.” Currently, three bills pending by Assemblymember Henry T. Perea (D-Fresno) would move California toward that goal.

AB 2208 would enable the state to combine clean water projects for small communities that can’t individually fund the improvements. AB 2238 champions a similar initiative to consolidate or extend infrastructure to unincorporated areas, which are predominately Latino and African American and include both remote agricultural labor settlements and islands within cities that lack municipal services.

“We have many of those types of communities all throughout the valley,” said Perea, recalling a tour he took of such locales conducted by Community Water Center that opened his eyes to the problem in places like Seville, Allensworth and Riverdale.

“Talking with the people with their inability to drink their water and cook with their water … there is a segment of our population that does not have that luxury,” he said. “They’re very poor. Spanish is usually their first language. We are not only the richest nation in the world but the richest nation in the history of the world. There’s no reason why in our state, in our nation, that people should be going without access to clean water.”

Meantime, he said such towns have separate elected water boards, which in some places are controlled by long-term members who operate with little transparency. The public often finds it hard to influence thse boards.

“The issue is really political,” Perea said. “In East Orosi, they have a very small trailer that serves as their water district office. They rarely post agendas, and they don’t even have a quorum much of the time. That I think is a poster child for what we’re trying to get at.”

One of Perea’s bills, AB 1669, would create a state “nitrate at risk area fund” that would use existing money for groundwater cleanup efforts. The idea complements a landmark report done by UC Davis called “Addressing Nitrate in California’s Drinking Water,” with findings released in March and more results to come.

The study used data from the 1940s through 2010 in the San Joaquin and Salinas valley areas collected by a host of agencies. Researchers determined that 254,000 people out of a 2.6 million total population are at risk for nitrate contamination of drinking water in those areas. Although toxic sources include waste water treatment plants and septic systems, 96 percent of the contamination comes from cropland.

Of that amount, more than half derives from chemical fertilizers that are rich in nitrogen, while about a third comes from dairy operations that recycle cow manure for nearby crops.

About 85 percent of California’s dairies are in the San Joaquin Valley, whose geography includes the Tulare Lake Basin. That ancient drainage zone stretches from Fresno County’s northern border at the San Joaquin River, to the southern end of Kern County at the Grapevine

Thomas Harter, a faculty member with UC Davis’ department of land air and water resources and a principal investigator for the report, said the San Joaquin and Salinas valley areas have an accrual of nitrates and salts that will lurk for decades, even were earnest remediation efforts to begin today. Ultimately, it is fiscally not feasible to “clean up” the entire groundwater supply, so drilling new wells and enhancing treatment measures are critical.

“That issue is not going to go away in two years or five years or 10 years. Putting measures in place to provide safe drinking water has to be a primary objective,” Harter said.

From a business angle, dairy farmers are keen to stay within regulations for well testing, and they are looking to apply fertilizer more precisely to prevent excess nitrates from seeping into the soil, said Jean-Pierre Cativiela, program coordinator for Dairy Cares, a coalition of industry groups in California.

“It’s not possible with current technology to farm without any fertilizer,” he said. “But you use fertilizer as efficiently as possible, apply it at the right time in the plant’s life cycle. We want to make sure we’re not overusing it.”

The workers who fuel the state’s industrial-scale agriculture tend to live in tiny settlements. “What’s really striking is how small some of these communities are,” Cativiela said. “They wouldn’t even meet most people’s definition of a town.”

The settlements are dependent on shallow wells drilled perhaps 50 years ago. The wells don’t reach aquifers. Fixing the problem will require a strategic, regional plan to remediate or replace them. Wells are even contaminated with arsenic and uranium in some places, Cativiela said.

“The average dairy farmer is spending $20,000 per year on compliance. The industry as a whole is spending $20 million per year. Nobody gets off free on this,” he said, echoing the scientific concerns over the San Joaquin Valley’s catchall problem. “It’s an enclosed basin. There’s no outlets. Any salts that accumulate there will be there for the foreseeable future. It must be managed carefully.”

Both Cativiela and Herrera said there has been tension between industry and advocacy groups, with the former pointing to the decades-long “legacy” of the dilemma, and the latter pushing for greater business help in monitoring wells. But both agreed that clean water for everyone is a common goal, as is a robust farming enterprise.

“My father, he’s worked in the farm industry for 20-something years. We understand that agriculture is important,” Herrera said. “We’re fundamental believers that the community should have access to a job and clean water.”