Stockton's Water Pollution: Sources And Causes

Stockton, California, has a long history as a regional transportation hub, and in recent years, the city has experienced high levels of air pollution. While air quality readings in July 2021 were rated 'good', the water supply in Stockton has been found to contain low levels of arsenic, Chromium 6, and nitrate. Water sources in the city are vulnerable to contamination from various activities, and water pollution prevention is a priority for local authorities.

Groundwater sources contain arsenic

Arsenic is a toxic metal that is known to cause cancer and other health issues in humans. Arsenic contamination of groundwater is a problem in many areas of the world, including California. In Stockton, California, the drinking water has detectable levels of arsenic, with an average of 3.6 parts per billion according to recent data. This is because Stockton, like other municipalities in the region, pulls water from groundwater sources, which are more vulnerable to arsenic contamination.

Groundwater sources can become contaminated with arsenic through human activities or natural processes. In the case of Stockton, California, the contamination likely originates from the source water itself, as arsenic is more prominent in areas that rely on groundwater sources. Natural processes, such as the recent increase in groundwater pumping, have also been found to contribute to higher arsenic concentrations in California aquifers. This is particularly true in the San Joaquin Valley, where historic groundwater pumping shows no link to current arsenic concentrations, indicating that recent pumping has played a significant role in the release of arsenic from clay strata within aquifers.

The problem of arsenic in groundwater is not unique to Stockton, California, or even the United States. Globally, groundwater provides almost half of all drinking water, and many communities face the challenge of arsenic-contaminated water. For example, in Arizona, communities like the Navajo Nation struggle with arsenic issues due to the area's history of mining operations. Similarly, in Bangladesh, high levels of arsenic have been found in both shallow and deep wells, impacting the water supply for millions of people.

The World Health Organization (WHO) estimates that over 200 million people worldwide have water sources that contain arsenic concentrations exceeding the recommended drinking water limit. This issue is particularly severe in southeastern Asia, but it also affects other regions, including the Rocky Mountains and the Interior Plains in the western United States. Despite meeting federal and state standards, the presence of arsenic in Stockton's water supply is a concern, and the EPA continues to research the health effects of low-level arsenic exposure.

To address the issue of arsenic in groundwater, new and more efficient treatment options have been explored. However, the costs of implementing the required physical infrastructure and equipment are often prohibitive. Technological innovations, such as combining membrane distillation with solar panels, offer low-cost solutions that have been adopted by small communities in the United States, including the Navajo Nation.

Chromium 6 from industrial discharge

Chromium 6, also known as hexavalent chromium or chromium (VI), is a toxic metal that is not regulated by the EPA. It is, however, produced and discharged in large quantities by certain industries. Chromium 6 is commonly released into the environment as a result of industrial activities such as steel processing, tanning, and metal plating. These processes can result in chromium 6 being discharged into water sources, leading to pollution. Chromium 6 is also formed during "hot work" such as welding on stainless steel or melting chromium metal, where high temperatures cause chromium to convert to a hexavalent state.

In Stockton, California, the tap and drinking water have been found to contain Chromium 6 at levels averaging 790 parts per trillion. This is significantly higher than the concentration determined by the state of California to have a negligible impact on cancer risk. The presence of Chromium 6 in Stockton's water supply is likely due to industrial activities in the region.

The impact of Chromium 6 on human health is a significant concern. It has been identified as a carcinogen, particularly if inhaled, where it can cause lung cancer. Exposure to Chromium 6 has also been positively associated with cancer of the nose and nasal sinuses. The high levels of Chromium 6 in Stockton's water supply may pose a health risk to residents, especially those with children.

To address the issue of Chromium 6 pollution in Stockton, it is important to implement measures to prevent industrial discharge of this toxic metal into water sources. This may include stricter regulations and enforcement of existing regulations by the EPA and local governments. Additionally, efforts to clean up and remediate contaminated sites can help reduce the impact of Chromium 6 on the environment and human health.

Water suppliers in Stockton, such as Cal Water, play a crucial role in ensuring water quality and safety. Cal Water conducts regular testing and monitoring of the water supply and has implemented a water quality assurance program. They also maintain and upgrade their infrastructure to ensure a reliable and high-quality water supply. However, it is important for residents to also take steps to remove Chromium 6 from their water, especially considering the potential health risks associated with this contaminant.

Nitrate levels in drinking water

Nitrates are a common contaminant in drinking water, and they can have harmful effects on human health. Nitrates are a type of fertilizer chemical that often contaminates drinking water through agricultural and urban runoff and discharges from municipal wastewater treatment plants and septic tanks. While nitrate levels vary across California, they are a significant concern in Stockton's water supply.

According to the Environmental Working Group (EWG), the safe nitrate level in drinking water is 0.14 parts per million (ppm) or 0.06 parts per billion (ppb) for the group of nine haloacetic acids (HAA9). However, Stockton's water system, which includes a mix of local groundwater and water purchased from the Stockton East Water District, often contains detectable levels of arsenic and other contaminants. The presence of arsenic in Stockton's water supply is a particular cause for concern, as it is a known carcinogen and can lead to other health issues such as skin damage and circulatory problems.

The City of Stockton has acknowledged the presence of low levels of arsenic in its drinking water, stating that the standards for arsenic balance the understanding of its potential health effects against the costs of removal. While the city's water meets federal and state standards, residents are advised to take steps to remove arsenic from their water, especially if they have children. This can be achieved through the use of specialized water filters designed for this purpose.

In addition to arsenic, Stockton's drinking water has been found to contain Chromium 6, another toxic metal that is not regulated by the EPA. The levels of Chromium 6 in Stockton's water supply are significantly higher than the concentration considered safe by the state of California. Disinfection byproducts (DBPs) are also a concern, as they can form when chlorine-based disinfectants react with naturally occurring organic matter. These byproducts have been linked to an increased risk of bladder cancer and other health issues.

To address water pollution and ensure safe drinking water, the Division of Drinking Water (DDW) in California requires public water systems to analyze for nitrates and report the results. The DDW also encourages customers to join efforts to prevent water pollution and protect natural resources. Water companies in Stockton, such as Cal Water, conduct thousands of tests on water samples annually and work to maintain and upgrade their infrastructure to provide reliable, high-quality water to their customers.

Air pollution from vehicles and industry

Stockton, California, has seen high levels of air pollution in recent years. The city has a long history as a regional transportation hub, and its air quality is affected by vehicle emissions. Cars, motorbikes, trucks, lorries, and buses release large amounts of chemical compounds and fine particles into the atmosphere, contributing to the city's air pollution. Larger freight vehicles, in particular, often use diesel as a fuel source, which results in higher pollution levels than smaller vehicles.

The maritime industry is also a source of air pollution in Stockton. While docked at the Port of Stockton, vessels are required to switch off their main engines and use auxiliary diesel and steam engines to power refrigeration, lights, pumps, and other functions. It is estimated that around one-third of vessel emissions occur while they are at berth. To mitigate this, the Port assists ship operators by providing visible emissions monitoring and information on air quality standards. The Port also works with the San Joaquin Valley Air Pollution Control District to enforce regulations and reduce air impacts.

In addition to vehicle and maritime emissions, industrial sites such as power plants and factories contribute to air pollution in Stockton. The combustion of fossil fuels at these facilities releases particle pollution and other harmful substances into the atmosphere. While efforts have been made to reduce fossil fuel usage, the use of fossil fuels in industry persists and contributes to poor air quality.

The high levels of air pollution in Stockton have potential health risks for its residents. Breathing polluted air can lead to respiratory issues and increase the risk of developing chronic obstructive pulmonary disease (COPD), which includes ailments such as bronchitis, emphysema, pneumonia, and asthma. Prolonged exposure to air pollution has also been linked to an increased risk of skin and lung cancer, as well as other skin conditions such as atopic dermatitis, acne, eczema, and psoriasis.

Chlorination of drinking water systems

There are several methods for chlorinating drinking water systems, including chlorine injection systems and dry pellet chlorinators. Chlorine injection systems utilize a retention tank to store clean water and employ sophisticated technology to seamlessly integrate chlorine into the water flow, ensuring uniform distribution and consistent disinfection. These systems are designed to be precise and accurate, mitigating the risk of under or over-chlorination. They are also NSF/ANSI 61 and 372 certified, which means they have been evaluated for lead content in drinking water system components.

Dry pellet chlorinators, on the other hand, are devices that are mounted on wells. They release compressed chlorine tablets into the well water, with the amount of chlorine metered in proportion to water usage. As the pellet dissolves, it releases chlorine that reacts with and helps to eliminate contaminants in the well water. This option is often chosen by do-it-yourself homeowners as it can be easily installed and maintained.

In Stockton, California, the water supply is vulnerable to various contaminants, including arsenic and Chromium 6. While the city's water meets federal and state standards, the presence of these contaminants can have negative health effects, especially over the long term. To address this, the city has implemented various measures, including the use of water filtration and the Urban Water Management Plan, which aims to ensure adequate and reliable water supplies for current and future demands.

It is important for communities to prioritize safe drinking water and take proactive measures to prevent water pollution. By investing in infrastructure, reducing water loss, and promoting sustainable water use, cities like Stockton can work towards ensuring a reliable supply of clean and safe drinking water for their residents.

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