Los Angeles' Troubling Impact On Water Pollution

Los Angeles has a long history of water-related issues, from the early 20th-century Water Wars to present-day concerns about water quality and pollution. The city's rapid growth and urbanisation have led to various environmental challenges, with stormwater pollution being a significant contributor to water pollution in the region. Each month, residents of Los Angeles discard their cigarette butts on the ground over 915,000 times, and the county generates enough trash to fill Dodger Stadium every two weeks. This trash, along with other pollutants like household chemicals, bacteria, metals, and pet waste, ends up in the waterways, degrading natural resources and posing risks to public health and safety. The Los Angeles Flood Control District manages an extensive network of pipes and channels, including over 2,800 miles of underground storm drains, to capture and clean stormwater before it enters the waterways. However, recent wildfires and their aftermath have further complicated the issue, with ash, fire suppressants, and other hazardous materials contributing to water pollution.

Stormwater pollution

Each day, approximately 100 million gallons of contaminated water and debris drain through Los Angeles County's storm drain system, with the daily flow increasing to 10 billion gallons during rainy days. This polluted stormwater ends up in local creeks, rivers, and the ocean, posing serious health risks to people who swim or fish in these waters, especially near storm drain outlets. The Los Angeles County Department of Health Services has issued a standing rain advisory, recommending that beachgoers avoid contact with ocean water, particularly near flowing storm drains, creeks, and rivers, for three days after rainfall.

The sources of stormwater pollution in Los Angeles include trash, cigarette butts, animal waste, pesticides, motor oil, and other contaminants left on the ground or washed into storm drains. These pollutants mix with rainwater and flow untreated into waterways, degrading the environment and posing health risks to residents and visitors.

The issue of stormwater pollution in Los Angeles has been long-standing, with little progress made in reducing pollution levels. Local municipalities have been working towards meeting their stormwater pollution reduction goals, but they have been criticized for their slow pace and lack of effective regulatory measures. The separate storm drainage and sewer systems in LA have also been identified as a contributing factor, as stormwater is not treated before being discharged.

To address this issue, collaborative plans and regulatory guidelines have been proposed, along with increased funding for stormwater projects. Efforts to raise awareness and encourage documentation of polluted waterways are also underway, with the goal of holding government officials accountable and expediting progress in improving water quality in Los Angeles.

Wildfire debris

Wildfires are a natural process in many ecosystems, but they are increasing in size, severity, and frequency in many areas of the United States. Wildfires can have a significant impact on water quality, both during the active burning of a wildfire and for years afterward.

After a wildfire, the loss of canopy vegetation and changes to soil properties can result in more water flowing over the land surface during storms, leading to flooding, erosion, and the delivery of sediment, ash, pollutants, and debris to surface water. This can result in decreased water quality, loss of reservoir storage capacity, stream habitat degradation, and increased treatment costs for drinking water providers. The magnitude of the effects of fire on water quality is primarily driven by fire severity (how much of the fuel is consumed) and fire intensity (how hot the fire burned). The more severe the fire, the greater the amount of fuel consumed, and the more nutrients released, making the watershed more susceptible to soil erosion.

Burning vegetation also releases nutrients contained within plants, including nitrate, ammonia, and phosphate. At high concentrations, ammonia can be toxic to fish and other aquatic life. Elevated nutrient concentrations, especially nitrate, can be a concern if downstream uses include a public drinking water supply. Increases in nitrogen and phosphorus concentrations can also lead to algal blooms, resulting in extreme daily fluctuations in oxygen or oxygen depletion as plant photosynthesis, respiration, and decomposition intensify. Anaerobic conditions (a lack of oxygen) stress aquatic organisms and can alter a wide range of chemical equilibria, potentially mobilizing certain toxic pollutants.

In addition to the impacts of wildfire on water quality, interactions between forested and urban landscapes can lead to reciprocal effects on water supply and ecology. Air pollution from urban areas can be deposited on adjacent forests, and wildfires can remobilize these contaminants. Wildfires can also introduce fire retardant chemicals into water bodies, which can reach levels toxic to aquatic organisms. Fire retardants typically contain large amounts of nitrogen in the form of ammonia, and they can cause water quality problems when fire-suppressing drops are made close to streams.

In the case of Los Angeles, wildfires can amplify the existing problem of water pollution in the region. Heal the Bay's staff scientists collected ocean-water samples from 10 shoreline sites along Santa Monica Bay to test for heavy metals, PCBs, asbestos, and other toxins. These harmful pollutants are flowing unchecked into the sea from heavy rains and other runoff from burn zones. The Los Angeles County Department of Health Services has also recognized the increased health danger associated with stormwater pollution, issuing a rain advisory that recommends beach users avoid contact with ocean water, especially near flowing storm drains, creeks, and rivers for three days after rainfall ends.

Industrial chemicals

Industrial activities are a major contributor to water pollution in Los Angeles. The city's industrial sector uses and produces a wide range of chemicals that can find their way into water sources, leading to contamination. This includes toxic chemicals such as coolants, oil, and antifreeze, which can leak from vehicles and machinery, as well as hazardous waste that is improperly disposed of by businesses. These chemicals can contaminate groundwater and surface water sources, posing risks to both the environment and human health.

One of the primary ways in which industrial chemicals contribute to water pollution in Los Angeles is through wastewater discharge. Industrial facilities often release untreated or partially treated wastewater into water bodies, which contains a range of harmful chemicals. This can include chemicals used in manufacturing processes, as well as those used for cleaning and maintenance. These chemicals can have toxic effects on aquatic life and can also accumulate in the tissue of fish and other seafood, eventually making their way up the food chain.

Another way in which industrial chemicals enter water sources is through runoff from industrial sites. When it rains, water can wash over industrial areas, picking up chemicals and contaminants as it flows. This polluted stormwater then drains into nearby water bodies, carrying with it a range of harmful substances. This is a particular issue in Los Angeles, where stormwater pollution has been identified as a leading source of pollution in the county's inland rivers, creeks, ocean, and beaches. The Los Angeles County Department of Health Services has issued a standing rain advisory, recommending that beachgoers avoid contact with ocean water near storm drains, creeks, and rivers for three days after rainfall to minimize health risks.

In addition to these direct sources of contamination, industrial activities can also contribute to water pollution in Los Angeles through air emissions. Certain chemicals released into the air can eventually find their way into water sources. For example, dry cleaning facilities, automotive shops, and metalworking industries can release chemicals such as tetrachloroethylene (perc) and trichloroethylene into the air, which then settle onto soil and groundwater. These chemicals have been linked to cancer and other serious health issues.

To address the issue of industrial chemical pollution in Los Angeles' water sources, local, state, and federal agencies have implemented various rules and regulations. These include guidelines on the types and amounts of chemicals that businesses can use, as well as strict standards for water quality established by the U.S. Environmental Protection Agency. However, the complex and varied nature of industrial chemicals makes it challenging to test for and regulate all potential contaminants. As a result, residents of Los Angeles may need to take additional steps to ensure the safety of their water, such as installing home water filtration systems.

Public health risks

Stormwater pollution is a major environmental and public health issue in Los Angeles, leading to unsanitary living environments and unhealthy water sources. The Los Angeles County Department of Health Services has acknowledged the heightened health risks associated with stormwater pollution, particularly the dangers it poses to beachgoers.

The county's beaches have been deemed hazardous to human health, with high levels of bacteria and other contaminants. During 2002, there were 269 warnings posted, resulting in 1,181 days where the ocean was too polluted for human use. The Santa Monica Bay Restoration Project also found that stormwater pollution increases the risk of viral infections, earaches, sinus problems, fever, flu, skin rashes, and viral diseases such as hepatitis for those swimming in the ocean near storm drain outlets.

Trash, animal waste, and cigarette butts discarded on the ground contribute to the spread of harmful bacteria, endangering the health of children and families in their communities. Cigarette butts, in particular, pose risks of swallowing, choking, or burning, as they are often laced with toxins.

The recent wildfires in Los Angeles have exacerbated the issue, with the first flush carrying higher levels of typical pollutants, as well as wildfire debris and hazardous materials. These contaminants pose significant risks to water quality and public health.

The Los Angeles Department of Water and Power routinely tests its water supply for over 200 contaminants throughout the year, and water quality reports are made available to the public. However, it is impossible to test for all potential contaminants, and the presence of industrial chemicals and impurities is a persistent concern.

Water treatment methods

Stormwater pollution is a significant issue in Los Angeles, with around 100 million gallons of contaminated water and debris draining through the storm drain system each day. This pollution has severe impacts on the region's water quality and poses risks to the health and safety of residents. The Los Angeles County Department of Health Services has issued a rain advisory, recommending that people avoid contact with ocean water near flowing storm drains, creeks, and rivers for three days after rainfall.

To address water pollution, various water treatment methods are employed. Here are some common approaches:

Filtration

Filtration is a technique that removes pollutants based on their particle size. Different types of filters are used depending on the specific contaminants in the water. Particle filtration and membrane filtration are the two primary forms of wastewater filtration. Membrane filtration can remove suspended solids, organic components, and inorganic pollutants such as heavy metals.

Sedimentation

Sedimentation is a critical wastewater treatment procedure. It involves using gravity to separate particles from the fluid. The decrease in water velocity allows particles to settle by gravitational force.

Disinfection

Disinfection is used to kill dangerous bacteria, viruses, and other pathogens. Chlorine, ozone, and ultraviolet light are common methods of disinfection.

Constructed Wetlands

Constructed wetlands mimic natural processes to treat wastewater. Water flows into a lined cell with plants, and the roots filter out contaminants. This method is similar to the Biological Nutrient Removal process.

Rapid Infiltration

In rapid infiltration, a basin is filled with pre-treated wastewater. The ground acts as a natural filter, removing pollutants from the water, similar to a septic system.

Chemical Precipitation

Chemical precipitation reduces heavy metal concentrations in wastewater. Dissolved metal ions are transformed into an insoluble phase through a chemical reaction with a precipitant agent such as lime.

Primary and Secondary Treatment

Primary treatment uses screens and settling tanks to remove solids and large materials from wastewater. The water is then partially treated and moves to the secondary treatment level, where bacteria digest the remaining pollutants with the help of oxygen.

Frequently asked questions