A recent report by the Arizona State Auditor General has found that the Arizona Department of Environmental Quality (ADEQ) has failed to monitor groundwater for agricultural pesticides as well as other harmful contaminants for more than six years. Furthermore, ADEQ did not conduct key groundwater monitoring procedures over a four year period, despite being legally required to do so. The lack of monitoring waterway quality led to an increase in the number of polluted surface freshwater systems across Arizona.

According to Beyond Pesticides, pesticide contamination of freshwater systems is historically ubiquitous throughout the United States, with at least five (very often more) different pesticides typically found in 90% of all water samples tested. Pesticides enter freshwater systems from agricultural as well as non-agricultural sources around the country, contaminating important sources of drinking water, such as groundwater and surface water systems that fulfill this vital role.

The Arizona State Auditor General conducted the report in order to establish whether the Arizona Department of Environmental Quality's Water Quality Division, who is responsible for protecting and improving waterways and groundwater systems under their jurisdiction, upheld their responsibility to develop water quality standards for aquifers. To develop aquifer water quality standards, ADEQ is required to conduct regular groundwater monitoring, including routine monitoring of agricultural pesticides in both groundwater and in surrounding soils, and to reduce the number of impaired surface water systems in the state. The report also investigates whether the agency monitored waterways for contamination by PFAS chemicals — a group of long-lasting chemicals that are known to have severe health impacts.

The report found that ADEQ failed to develop aquifer water quality standards for eight toxic contaminants (arsenic, bromate, chlorobenzene, chlorite, coliform bacteria, haloacetic acid, trihalomethane and uranium), which have been linked to serious health issues, including kidney problems and a greater risk of various forms of cancer. Consequently, aquifers that supply water to groundwater systems that serve as sources of drinking water are not protected from these pollutants, reducing drinking water safety, particularly for those that depend on private wells for their drinking water. Furthermore, the report found that the agency failed to meet aquifer water quality standard development objectives for the above pollutants for the past 7-29 years and did not monitor ambient groundwater that plays a crucial role in detecting and assessing the impact of contamination by chemicals. The agency also failed to monitor groundwater and surrounding soil for contamination by agricultural pesticides.

While the Arizona Department of Environmental Quality aimed to reduce the number of impaired surface waters to comply with federal surface water quality standards, the report found that between 2014-2020 the number of contaminated surface waters in the state increased by 19 (from 136 to 155), with PFAS contamination continuing to pose a significant health risk.

Another grave cause for concern is that pesticide contamination in surface and groundwater sources that are inadequately monitored could lead to these toxic chemicals accumulating in aquatic systems, and ultimately in drinking water. The EPA has regulations such as the Clean Water Act and the Safe Drinking Water Act in place that were designed to protect both human and environmental health, however, these regulations were rolled back by the previous administration and currently do not adequately protect the health of aquatic systems that freshwater, marine and terrestrial animals (including humans) depend on for their survival.

This report highlights an all too common problem of government and state agencies failing to fulfill their duty to protect both the environment and the public from exposure to harmful toxic contaminants. Aquatic systems receive a continual stream of environmental contaminants, and this report highlights that when toxic pollutants go unmonitored they can exist in water sources at levels that exceed those stipulated by federal drinking water standards.

Pesticides are widely used across the US and therefore are continually flowing into surface waters and groundwater systems that serve as important sources of drinking water for half the country's population. As the health impact of many pesticides can be amplified when they combine with other pesticides, the environmental and human health impact of exposure to multiple pesticides is likely to be far more significant than exposure to just one pesticide alone. Besides being extremely toxic to aquatic organisms, pesticides can cause a wide range of adverse health effects in humans and animals, including reproductive defects, neurotoxicity, endocrine disruption, and an increased risk of cancer.

According to advocacy group Beyond Pesticides, current levels of pesticides in US waterways are very concerning, but could get much worse due to climate change impacts such as melting glaciers, which could release pesticides and other persistent contaminants trapped within the ice. Beyond Pesticides is lobbying for the phasing out and ultimately the complete elimination of pesticides to protect waterways and ensure drinking water safety. In the meantime, you can take precautions to ensure you are not exposed to pesticides and other toxic drinking water contaminants that can endanger your health by investing in a good berkey water filter that is capable of removing pesticides and other common drinking water contaminants.

To find out more about the problem of pesticides in drinking water read the informative article by Beyond Pesticides: Pesticides in My Drinking Water? Individual Precautionary Measures and Community Action.