Surface water pollution from urban pesticide use is a known, widespread
problem in the U.S. This has been documented not only by USGS, but
also by numerous scientific studies by academic researchers, data from
municipal urban runoff programs, and surface water impairment
designations under section 303(d) of the Clean Water Act (often these
listings are for "toxicity" rather than a specific pesticide). U.S.
EPA's pesticides office is keenly aware of this problem.
Pesticide-related Toxicity in Surface Waters
In
California, pesticide-related toxicity in surface waters receiving
urban runoff is has been severe and widespread since the mid-1990s.
Addressing this toxicity is a priority for Calfornia's water and
pesticide regulators. With the phase-out of most urban uses of diazinon
and chlorpyrifos, the toxicity has shifted--it is now occurring in both
the water column (during storm events) and sediments (all the time) in
urban creeks across California.
The current
toxicity is associated with the use of the currently most common class
of urban insecticides--the pyrethroids (i.e. bifenthrin, cypermethrin,
cyfluthrin, etc.). Similar toxicity has also been documented in Texas
urban areas.
Substituting Pesticides Also Causes Biodiversity ProblemsSince
some in this thread mentioned pesticide phase outs, it is important to
recognize that the likely substitute for pyrethroids is fipronil, which
is already seeing growing use in California--and is beginning to appear
in surface water at levels close to those known to be toxic to
sensitive aquatic organisms. It is becoming clear that simply changing
pesticides isn't going to solve these water quality problems.
Professional Insecticide Applicators Are the LinkSubstantial
effort is underway in California to identify the sources of
pesticide-related urban surface water toxicity. Available data show a
direct link to outdoor, above-ground insecticide applications by
professional applicators.
Ants Are the Most Common Insect Problem in CaliforniaIn
California, ants are the most common insect problem and it is a common
practice (particularly among commercial property owners and
multi-family residential property managers) to retain a professional
applicator to spray a band of insecticides around structures every 1-2
months. Much of the treated area around structures is impervious
surface, some of which is directly connected to storm drains (DCIA).
Pre-construction termiticide and Post-construction PyrethroidsOther
possible sources include pre-construction termiticide ground surface
treatments (if a rain event occurs before building foundations are
poured), and both professional and non-professional applications in
other outdoor locations (applications to lawns/landscaping have not
been ruled out as potentially meaningful contributors to toxicity).
Underground
injection of pyrethroids (i.e., for post-construction termite control)
is unlikely to contribute to surface water toxicity. Most California
municipalities are served by separate storm drain systems comprised
completely of hard surfaces (i.e., no vegetated channels)--thus
pesticides in runoff are efficiently delivered to urban creeks.
Greatest Water Pollution Problem: Insecticides vs Herbicides There
is a long-time myth that homeowner lawn/garden applications of
pesticides (particularly herbicides) are a big problem. Maybe they are
in some locations, but available scientific data strongly suggest that
insecticides--not herbicides--are of greatest concern in urban areas
and that (at least in California) professional pesticide
applications--and intentional applications of pesticides to impervious
surfaces--should be the priorities for stormwater quality management.
Urban Pesticides Pollution Prevention Project (UP3 Project)With
grant funding from the California State Water Resources Control Board,
the Urban Pesticides Pollution Prevention Project (UP3 Project) is
working with U.S. EPA, California EPA, municipalities, and other
stakeholders to understand and prevent pesticide-related surface water
pollution. Pesticide regulators and pesticide manufacturers are aware
of these problems and are working to change their systems to address
them. For more information (and reports that document the statements
above), please see
www.up3project.org.
Kelly Moran, Ph.D.
TDC Environmental
UP3 Project
P.S.
Wastewater treatment plants are not immune to pesticide-related
problems. Discharges of certain pesticides (including biocides) to
municipal wastewater treatment plants have been problematic, in some
instances, for compliance with NPDES permit effluent limitations and
operation of biological treatment processes.
