Polluted Shores, Unequal Risk: Water Quality at 40th Street Extension, Manhattan Beach, CA (Santiago Avelar, Andre De Anda, Keven Cortez)

Recurring bacterial warnings and elevated contamination at the 40th street extension reveal patterns like stormwater runoff, aging coastal architecture, and better community center response controls. Manhattan’s beach shoreline, including the 40th street extension, is always a hot spot for water-quality monitoring. Recently, the LA County Public Health Department has given ocean water use warnings regarding the 40th street extension after tests demonstrated an increase in bacteria levels. Independent papers like the Heal the Bay’s Beach Report Card have put this extension in a mixed grade range that can go down after storms. Issues like these have led to an increase in health concerns for common beachgoers like swimmers, surfers, shoreline workers, and nearby residents who are reliant on this area for recreation and employment. The 40th street extension is a heavily used recreational spot in the South Bay that attracts local residents and visitors alike for activities that include: swimming, surfing, and general beach activity. High usage of this area has led to an increase in accurate water-quality monitoring. There are several agencies and organizations which provide information regarding this area.The Los Angeles County Public Health Department has issued official advisories and closures, state monitoring programs provide additional data of regulations, and nongovernmental organizations (NGO) like Heal the Bay provide independent water-quality grades and models that help with predictive contamination. When sampling detects fecal-indicator bacteria (FIB) above fitness measure, county officials issue ocean-warnings that most often extend 100 yards up and down the shoreline from the affected area. The most common short-term contaminants present during advisories are fecal-indictator bacteria such as enterococci and total coliforms, which are used as markers for a possible presence of pathogens. High levels are usually connected to stormwater runoff, deteriorating sewage infrastructure, illegal dumpings, and post-fire runoff events that move pollutants into the coast. An excess of these bacteria trigger county/state warnings that instruct the public to avoid contact with water until levels fall below health standards (Heal the Bay). In the 40th Street Extension’s case, LA County Public Health has issued warnings on multiple occasions in recent years, usually after rain events or late-summer periods when bacterial levels periodically increase. County bulletins and media reports consistently list the 40th Street Extension among the impacted areas. They advise beach users to avoid entering the water within a 100-yard radius of the testing site (GovDelivery FOX 11 Los Angeles). Heal the Bay’s Beach Report Card shows similar trends. The Manhattan State Beach sampling site near 40th street often earns high grades in dry weather, but experiences notable declines during wet-weather sampling, showing how even beaches with strong overall annual performance can quickly become unsafe thanks to storm-driven contamination (Heal the Bay). The public-health consequences of these bacterial spikes are extremely important. Short-term exposure risks include: gastrointestinal illness, eye and ear infections, and skin rashes. For shoreline workers like lifeguards, surf instructors, and vendors (and also residents who use the beach for regular recreational activities), repeated/unpredictable advisories both are big factors to health vulnerabilities and economic/recreational losses. These impacts don’t fall proportionally on people and communities with limited access to alternative safe recreational areas  (Los Angeles County Public Health). Overall, the recurring contamination at the 40th Street Extension shows the urgent need for improved monitoring, infrastructure repair, and community-responsive measures to protect public health. (Santiago A.)

Southern California’s rainy seasons wash bacteria, pet waste, automobile fluids, and other pollutants from streets into storm drains that discharge near popular beach access points. The 40th Street extension is vulnerable to this because of the heavy rain and urban runoff which correlates with rapid drops in wet weather water quality. Also, Heal the Bay’s analyses and local public health notifications repeatedly identify runoff as a key component of transient contamination events. (Heal the Bay)

County advisories have sometimes been triggered by sewage discharges or infrastructure failures in the watershed. While these major sewer system failures don’t happen on a daily basis, even inconsistent spills combined with limited rapid response containment can and will elevate the risk to nearshore waters. County closure notices historically cite sewage discharge or suspicious runoff as triggers for broader closures. (GovDelivery)

Although Manhattan Beach itself is relatively well when it comes to water flow, the broader patterns of coastal contamination don’t fall proportionally; they burden communities of color and low-income neighborhoods in the Los Angeles region areas that may lack political power or resources to demand rapid infrastructure upgrades in their areas of living. Additionally, visitors who rely on public beaches as accessible recreation (including families, youth, and renters) are affected when advisories reduce safe swimming opportunities. While the immediate area of 40th Street serves many nearby residents and visitors, the structural drivers (regional stormwater policy, county infrastructure investment, and enforcement) reflect environmental injustice dynamics across the county. Relevant reporting and advocacy by NGOs emphasize that wet-weather pollution and infrastructure failures are not experienced equally across all Los Angeles communities.(Heal the Bay) (Andre DA)

We can start by improving public health protection at the 40th Street extension by adding real-time monitoring and more responsive public alerts. Using NowCast-style forecasting and taking water quality samples more often around popular shoreline sites would bring down the risk of exposure that residents have to harmful conditions. This communication helps build trust with the community and allows beachgoers to make informed decisions. NGOs like Heal the Bay and county health use these tools, and expanding their audience would provide consistent protection Heal the Bay). Another step is to up the investment in green stormwater architecture throughout the watershed that drains toward 40th Street. Things like Bioswales, permeable pavement, rain gardens, and infiltration systems can reduce runoff intensity and bring down pollutant loads before they reach coastal waters. Nature-based solutions also bring additional benefits like reducing heat, adding green space, and improving quality of life in neighborhoods. Research by Heal the Bay and the state shows that reducing stormwater runoff helps improve better wet-beach grades (Heal the Bay). Infrastructure upgrades should also include rapid response plans and fixes the sewer and storm drain systems in the watershed. Updating old pipelines and increasing the frequency of inspections would reduce the likelihood of sewage-related beach advisories. County notices show that even suspected sewage leaks are enough to trigger larger advisories which is why preventing these incidents is so important. Stronger repair plans and emergency procedures keep the beaches safe (GovDelivery). Good communication with the community is very important for ensuring fair access to timely health information. Signs with multiple languages at beach access points, transit hubs, and nearby neighborhoods would help visitors and residents to understand current conditions. Outreach to local schools, organizations, and businesses could help provide advice on how to adjust events and programs during advisories (Los Angeles County Public Health). Youth engagement and citizen science programs like Heal the Bay can help persuade communities to participate in monitoring efforts and speak on long term solutions. This would strengthen the quality of the data and improve public involvement (Heal the Bay) (Keven C.)

Manhattan Beach’s 40th Street extension usually meets the safety standards, but it is the storms, urban runoff, and random discharges that push the bacterial levels above the health margin, creating irregular but dangerous risks, which also affect the extension's health standards. Still there are some fixes for this: monitoring and sewer upgrades that can be achieved, but what is needed and required as well is political will, targeted funding, and community-centered responses that can both protect public health and provide fair access to beaches where there is no longer such a dangerous risk. This would lead the residents, lifeguards, and visitors at 40th Street to face fewer surprise closures, clearer public guidance, and safer days at the beaches and its shores. Heal the Bay (Andre DA.)

Sources Used: 

Los Angeles County Department of Public Health — Beach Water Quality Advisories & Ocean Water Use Warnings (multiple bulletins referencing 40th Street extension warnings). Los Angeles County Public Health+1

Heal the Bay — Beach Report Card (Manhattan State Beach, at 40th Street site grades and analysis of wet-weather impacts). Heal the Bay+1

Local news coverage (FoxLA / ABC7 / Patch) reporting recent LA County ocean water warnings that included the 40th Street extension among affected beaches. FOX 11 Los Angeles+2ABC7 Los Angeles+2

County historical advisory record and archived notices referencing past sewage-related advisories and closures (content.govdelivery / county bulletins). GovDelivery+1

Heal the Bay Beach Report Card broader analysis on runoff, wet-weather grades, and regional patterns of contamination. Heal the Bay+1