California Water Pollution: Understanding The Root Causes

California's water quality is threatened by a variety of human and natural factors. While the Clean Water Act has helped reduce pollution from industrial outfalls, most water pollution in California is now caused by runoff from farms and cities, which has led to toxicity, respiratory diseases, and gastrointestinal illness. In addition, PFAS contamination has been detected in the tap water of millions of Californians, with more recent data suggesting that the number of people affected will continue to grow. Arsenic, nitrate, and 1,2,3-trichloropropane are among the most common contaminants in California's water systems, with about three-quarters of the failing systems violating state or federal standards for contaminants linked to serious health issues.

Nitrogen fertilizers and manure polluting groundwater basins

Nitrogen fertilizers and manure are significant contributors to California's water pollution problem, particularly in the form of nitrate pollution of groundwater basins. Nitrogen fertilizers and animal manure contain high levels of nitrate, which can leach into groundwater and contaminate it. This process is influenced by various factors, including the amount of fertilizer nitrogen leaching as nitrate, the stability of nitrate in the unsaturated zone and aquifers, and the amount and distribution of rainfall and irrigation.

The use of nitrogen fertilizers in agriculture has intensified in California, and this has contributed to the state's groundwater contamination. Investigations have revealed that nitrate is accumulating in the shallow groundwater of irrigated areas with intensive agriculture. The dairy cow population has doubled, and the broiler population has tripled, concentrating N-rich feed in California and further amplifying concerns about manure nitrogen handling.

Improper management of manure and fertilizers can have detrimental effects on water quality. When these substances enter surface water, they release nutrients that stimulate the growth and reproduction of microorganisms, reducing the dissolved oxygen content. This depletion of oxygen can suffocate fish and other aquatic species, degrading water quality and causing unpleasant odors. Additionally, runoff from fields with high levels of nitrogen and phosphorus can contaminate streams, wetlands, and lakes, further contributing to water pollution.

To address the issue of nitrogen fertilizers and manure polluting groundwater basins, several practices can be implemented. These include manure management to reduce ammonia emissions, soil management to decrease nitrate levels in groundwater, and fertilizer management to minimize nitrous oxide emissions. By improving irrigation management practices and increasing the efficiency of fertilizer nitrogen use, the risk of nitrate pollution from fertilizers can be reduced.

Effective wastewater management is also crucial in mitigating the impact of nitrogen fertilizers and manure on groundwater basins. Small communities in California face chronic water quality problems, and the treatment of contaminated water can be costly for these smaller systems. Therefore, it is essential to have durable funding for system operations and provide administrative support to encourage consolidation with larger systems.

Ineffective wastewater management

California's water quality is affected by both human actions and natural processes. Ineffective wastewater management is a significant challenge in the state, particularly in small communities. Here are some key factors contributing to this issue:

Aging Infrastructure

California's wastewater treatment plants face challenges due to aging infrastructure that requires upgrades, replacement, or expansion. The facilities, though technologically advanced, struggle with the increasing demands of a growing population and the reduced flows caused by drought and water conservation efforts.

Contaminants and Pollutants

Wastewater treatment in California must address a range of contaminants and pollutants, including pharmaceuticals, pesticides, herbicides, insecticides, and other chemicals. These substances can have detrimental effects on the environment and human health if not properly treated or disposed of.

Financial Constraints

Effective wastewater management is hindered by financial constraints, particularly in small communities. Treatment processes to remove contaminants can be costly, and small systems may lack the economies of scale to implement them effectively. Additionally, the consolidation of smaller systems with larger ones may be necessary but requires flexibility and administrative support.

Climate Change and Extreme Weather

The impacts of climate change and extreme weather events further complicate wastewater management in California. Drought conditions lead to reduced flows and affect water temperatures and oxygen levels in rivers and streams, threatening aquatic life and contributing to harmful algal blooms.

Regulatory Challenges

While California has implemented water quality regulations, such as the Porter-Cologne Water Quality Control Act and federal Clean Water and Safe Drinking Water Acts, there are ongoing discussions and concerns about the feasibility and impact of new conservation rules. Balancing the need for water conservation with the potential public trust and pushback from the public and the feasibility for smaller water agencies is a delicate task.

Industrial and urban runoff

California faces significant water quality challenges due to industrial and urban runoff. Urban runoff refers to any water flowing on urban surfaces, including storm flows and dry weather flows from activities such as over-irrigation and car washing. As this water flows over paved areas, it collects and carries a range of pollutants, creating a "toxic soup" known as urban runoff pollution or stormwater pollution. This pollution contains various contaminants, such as litter, pet waste, pesticides, fertilizers, and motor oil.

The diffuse nature of urban runoff makes it challenging to manage and control. When left unchecked, this pollution flows into creeks, rivers, and storm drainage systems, eventually reaching coastal oceans. This contamination can have detrimental effects on sensitive plant and animal communities, as well as posing risks to humans who come into contact with the water through activities such as swimming and surfing.

To address these issues, organizations like the Southern California Coastal Water Research Project (SCCWRP) have dedicated themselves to studying and mitigating runoff contamination. They have developed tools to estimate contamination levels and types based on land use and are working on strategies to optimize the effectiveness of stormwater Best Management Practices (BMPs) in reducing contamination. Additionally, regulatory programs have been established to set increasingly stringent requirements for protecting runoff water quality.

The City of Glendale, California, provides an example of local efforts to combat urban runoff pollution. They implement various stormwater pollution prevention programs, including street sweeping, storm drain cleaning, and litter pick-up. Glendale also leads and partners in projects that capture and treat polluted stormwater, aiming to protect their local waterways, such as the Los Angeles River and its tributaries.

While progress is being made, the complexity of urban runoff pollution requires continuous efforts and collaboration between different organizations and regulatory bodies to effectively manage and reduce the impact of industrial and urban runoff on California's water quality.

Groundwater over-pumping

Groundwater pumping in California has exceeded replenishment for decades, causing groundwater depletion or "overdraft". This is particularly true in the southern Central Valley, California's largest farming region, where overdraft is more than 10% of net water use.

The Central Valley accounts for 20% of groundwater withdrawals in the United States, with approximately 1 million people in the San Joaquin Valley relying on groundwater as their main source of drinking water. This high dependence on groundwater has resulted in overpumping, causing subsidence or massive compression of the ground, and arsenic contamination of the water. Arsenic is a naturally occurring element in the environment, but it is deadly to human health.

To address these issues, California passed the 2014 Sustainable Groundwater Management Act (SGMA). This law requires local agencies to address the undesirable impacts of overpumping and to bring their basins into balance by ending long-term overdraft.

Pesticides, metals, pathogens, trash, and sediment

California's water quality faces multiple and diverse challenges. These challenges are caused by both human actions and natural processes. Some contaminants are remnants of past activities, such as mercury from mining, while many other sources of pollution are ongoing.

Pesticides

Urban and agricultural stormwater and irrigation runoff carry pesticides into surface waters, creating toxic pulses that are lethal to small aquatic organisms. The Central Valley Regional Board has, since 1982, allowed farmers to discharge wastes into the state's waters without monitoring or implementing pollution control measures. Pesticides, especially diazinon and chlorpyrifos, have been found at toxic levels in the Sacramento and San Joaquin Rivers, contaminating the drinking water supplies for millions of Californians.

Metals

Nitrogen fertilizers and manure produce nitrates that pollute local groundwater basins. Other chemical contaminants include arsenic and chromium-6. Treatment to remove these contaminants can be costly, and small systems that do not benefit from economies of scale may struggle to implement them.

Pathogens

Pathogen contamination is the leading cause of stream water pollution in the US. About 53% of assessed rivers are impaired, and most of them are contaminated by pathogens. Pathogen influxes from agricultural lands are the main cause of stream impairments. However, there is a weak understanding of pathogen transport from these lands to rivers, which makes it challenging to implement effective land management practices to improve water quality.

Trash

Trash in California's coastal areas primarily originates from a diffuse storm drain network rather than beachgoers, boaters, or anglers. Storm drain systems efficiently move water off the land to prevent flooding, but they also transport trash from urban landscapes to the coastal zone. To combat this issue, California's stormwater management community has been installing mesh screens at storm drain entry points to deflect trash particles. More aggressive street sweeping and multi-benefit stormwater management projects are also part of the trash-reduction strategy.

Sediment

Sediment, along with other pollutants like trash, can enter water bodies through stormwater runoff. California's trash reduction program, implemented in phases over a 10- to 15-year span, includes capturing trash and implementing improved source control measures to slow and stop trash from entering storm drains.

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