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Dear Editor
The March 7 edition of the LA Times had a front page article about sewage plants failing
to kill lethal superbugs discharged to the sewer from local hospitals. The article strongly
implied that the discharge of treated wastewater from sewage treatment plants in Southern
California constitutes a public health threat.As the operators of the major public wastewater
treatment systems in Southern California,which serve over 12 million people and who are
fully committed to protection of public health and the environment,we would like to respond
to a few misconceptions in the article.
First, the title of the article states that sewage treatment plants are failing to kill lethal
superbugs discharged to sewers from hospitals. Superbugs, also known as CRE, are a type of
Antibiotic Resistant Bacteria(ARB) that have been linked to difficult-to-treat infections in
hospitals. While the title states that the treatment facilities fail to kill the superbugs,the
article only cites unpublished EPA data that indicates that superbugs are present in raw
sewage before treatment. The article indicates EPA did not analyze for CRE in treated
wastewater effluent in Southern California. The implication that CRE may also be present in
Southern California effluent is made by including a quote from Professor Pedro Alvarez,
indicating"a growing number of studies show sewage treatment plants can't kill the
superbugs". We are not familiar with exactly which studies are being cited but we are not
aware of studies that show the presence of viable(living) CRE bacteria in effluent from
treatment plants using treatment processes widely utilized in Southern California to produce
tertiary or advanced treated recycled water for reuse. With regard to the effluents from the
ocean discharging secondary treatment plants in Southern California,if viable CRE are
indeed present, their concentration would be limited by the fact that wastewater from
hospitals is an extremely small fraction of the total wastewater influent, only one-half per-
cent of the total influent at the City of Los Angeles' Hyperion Plant, for example. The
effluent from the ocean-discharging plants is discharged far off the coast,away from
recreational activities,highly diluted by seawater,and,based on decades of extensive
trucking and monitoring, does not flow back to beaches.
Identification of ARB in treated wastewater is a very new field of study. The Los
Angeles County Sanitation Districts have conducted research on the fate and transport of
non-CRE ARB through the treatment processes of its water reclamation plants and
demonstrated at least a 99.99%removal rate. Wastewater treatment plants test for indicator
bacteria to monitor the effectiveness of treatment and ensure protection of public health.
California's water quality standards were determined based on epidemiological studies
conducted in Santa Monica Bay that correlated indicator bacteria levels with incidence of
illness. If indicator bacteria levels are below applicable regulatory limits,the likelihood of
any pathogenic bacteria or viruses, including ARB,being in the water at an infective level is
essentially zero. Regular monitoring occurs at all Southern California wastewater facilities
and we are not aware of any data suggesting that viable CRE are more resistant than indicator
bacteria to removal by the treatment processes used by our agencies.
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Last,the article cites examples of surfers contracting illnesses after a rainstorm,implying
this public health issue is somehow tied to superbugs discharged to the sewer with hospital
wastewater. Stormwater systems and wastewater systems are completely separate in
Southern California. The discharge of treated effluent to inland surface waters and the ocean
does not pose a threat to recreation in wet or dry weather. Local public health officials
routinely post rain advisories after a rain storm due to high levels of indicator bacteria. These
closures are the result of discharge of stormwater(not wastewater).
To summarize,there is no evidence to suggest discharge of treated effluent from any of
our facilities poses a risk to public health as a result of bacterial infection. We will continue
to monitor and lead development of sound science to ensure our facilities continue to protect
public health.
Enrique Zaldivar,Director,City of Los Angeles Bureau of Sanitation
Grace Hyde, Chief Engineer&General Manager,Los Angeles County Sanitation Districts
Jim Herberg,General Manager,Orange County Sanitation District
WC 4 3644667