Farmworkers pick broccoli in the Salinas Valley.
Farmworkers pick broccoli in the Salinas Valley. Photo by Chris Stone

The water scarcity California has been experiencing over the last two decades is the result of the worst drought to hit the American Southwest in the past 1,200 years. While climate change plays a significant role in reducing precipitations, the unsustainable use of groundwater aquifers further diminishes the state’s limited water supplies. 

This ongoing issue has been a significant concern garnering Federal-level attention, with the Senate passing the Infrastructure Investments and Jobs Act in August 2021 to improve California’s critical water infrastructure. Concurrently, issues regarding water quality arise due to the state’s high use of pesticides in agriculture, with several Environmental Protection Agency-reapproved toxic herbicides not being regulated by state legislation.

Unsustainable Agriculture Threatens Water Quality

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From 2004 to 2015, over 2 billion pounds of pesticides have been used in California, with the most recent numbers indicating an annual use of 209 million pounds. Though it represents only 2-3% of total U.S. cropland, the Golden State uses up to 20% of all pesticides employed in the U.S. 

Even if it is a water-starved state, approximately 80% of California’s water supplies are used for intensive agricultural practices, primarily in the San Joaquin/Central Valley. The remaining 20% of the state’s water intended for the population is at risk of contamination from pesticides used for demanding high-value crops like almonds, cotton, and pistachios. 

Concerns over water safety are not misplaced. The EPA noted in 2002 that 635 miles of waterways crossing the Central Valley were compromised by agricultural pesticides, rendering the water unsafe for fishing, swimming, or drinking. Moreover, runoff from cultivated land that reaches the Sacramento and San Joaquin rivers can contaminate drinking water sources serving millions of Californians, including urban areas like San Francisco, Los Angeles, and San Diego.

Over the years, environmental advocacy groups have supported policies and programs to promote water safety by reducing excessive discharge from agricultural waste. Though progress is being made to address the issue, most regulations are flawed with deficient monitoring and a lack of enforceable standards.

Toxic Herbicides Remain Unregulated by Proposition 65

Since 1986, California’s Proposition 65 has ensured water safety by imposing limits and regulations for dangerous substances. While it regulates a list of almost 900 chemicals, several toxic pesticides remain unregulated by the California Environmental Protection Agency (CalEPA). 

For example, a toxic herbicide still available on the market, paraquat, has been extensively used for weeds that have become resistant to other dangerous pesticides like glyphosate. Its elevated toxicity led to the substance being banned in 32 countries, including the EU and China. 

California’s Office of Environmental Health Hazard Assessment (OEHHA), which updates the list of substances regulated by Proposition 65, doesn’t include paraquat in the few-provided and specific qualifying criteria for causing cancer, congenital disabilities, or reproductive harm. 

With 1,3 million pounds being applied in California in 2018, paraquat has been documented to produce reproductive issues in laboratory mice models, impacting human kidney and lung function and increasing the risk of Parkinson’s disease. Its widespread application in the agriculture-intensive San Joaquin Valley represents a genuine contamination threat to one of the state’s most important drinking water sources.

EPA Reapproves Paraquat Until 2035

Despite evidence indicating that it represents a severe threat to human health, in August 2021, the EPA approved paraquat’s registration renewal for another 15 years. Furthermore, it also allows its aerial application with a 50-75 foot buffer zone in residential communities.  

The agency’s decision was met with legal action from environmental, health, and farmworker groups. They cite the EPA’s disregard for workers’ and communities’ safety given paraquat’s adverse neurological effects. While the case is pending, California could use its extensive regulatory authority to ensure water quality and reduce the risk of toxic pollutants. 

This can be accomplished by OEHHA expanding Proposition 65’s limited qualifying criteria to include multiple types of harm, including respiratory, renal, and neurologic. This would allow setting definitive safety standards for paraquat and other unregulated herbicides that can end up in drinking water.

Even though the EPA may dispute paraquat’s neurotoxic potential, the agency needs to address the overall risk that pesticide contamination of water sources represents for humans and the environment. The agency could help states reduce pesticide pollution by developing comprehensive monitoring and rapid detection capabilities. 

In 2021 the EPA launched the Water Toxicity Sensor Challenge aiming to source innovative ideas for cost-efficient electrochemical biosensors to rapidly identify toxic pesticides in water sources. While the viability of electrochemical sensors has increased over the past decade, with certain models able to detect specific contaminants like paraquat at low concentrations, the EPA has yet to release any updates regarding its progress.

Ensuring the quality of California’s water supply requires updated regulation of substances used in the state’s vital agricultural sector and water management reforms. CalEPA should reconsider its evaluation criteria for legal toxic pesticides.

In the meantime, as long as the federal EPA will reapprove harmful herbicides, it could at least try to offset their impact by providing states with better abilities to detect and rapidly address contamination before it poses an even greater public health risk.

Stan Gottfredson serves as CEO of Atraxia Law, a San Diego-based firm that helps agricultural workers and their families affected by paraquat exposure compile the necessary information to support their Parkinson’s disease injury claims against liable manufacturers.