Environmental Engineering Reference
In-Depth Information
6 PCBs .................................................................................................................................. 150
6.1 Levels in Sport Fish................................................................................................... 150
6.2 California Sport Fish Guidance to Protect Human Health ........................................ 152
7 Summary ............................................................................................................................ 153
References ................................................................................................................................. 155
1
Introduction
DDT (dichlorodiphenyltrichloroethane), chlordane, toxaphene and PCBs (polychlori-
nated biphenyls) are persistent organochlorine chemicals that can still be widely found
in soils and aquatic environments decades after use has been discontinued. Under the
Clean Water Act, these chemicals are regulated by a total maximum daily load
(TMDL) for each watershed to achieve levels that are not toxic to wildlife or humans.
In Newport Bay and Watershed (Orange County, California), the development of
TMDLs for these legacy organochlorines has been underway for more than a decade.
In 2002, the United States Environmental Protection Agency, Region IX (US EPA
Region IX) promulgated TMDLs for DDT, chlordane, toxaphene and PCBs in
Newport Bay and Watershed. The fi nding of impairment, and therefore the necessity
for the TMDLs, was based on certain target concentrations for water, sediment and
fi sh. The Santa Ana Regional Water Quality Control Board (SARWQCB or Regional
Board) revised and approved these TMDLs in 2007, with the condition that an inde-
pendent advisory panel (IAP) of experts review the science underlying the TMDL
targets. The IAP was formed by Orange County. They met and considered the TMDLs
and the underlying science. They pointed out fl aws in the science supporting the
TMDLs and recommended developing TMDLs based on site specifi c food chain bio-
accumulation of the legacy organochlorines (IAP
2009
). The California State Water
Resources Control Board (CSWRCB or State Board) and Region IX of the USEPA
have recently approved the 2007 TMDLs; implementation of the TMDLs and recon-
sideration of their targets based on the IAP recommendations was begun in 2013.
The regulated community has pointed out throughout the TMDL proceedings that
these organochlorines are no longer in use, that residue levels are declining, and that
there are no apparent effects on wildlife or human health. They have also pointed out that
many of the targets to be implemented are not based on sound
science. The important question for all concerned is whether the chosen targets are sci-
entifi cally sound and whether current levels meet or exceed scientifi cally sound targets.
Technical reports that address different aspects of the TMDL process or the
targets have been written by US EPA Region IX (
2002
), SARWQCB (
2006
) and
scientists working for the regulated community (Flow Science et al.
2006
; Byard
2011
,
2012a
,
b
). Scientists representing the regulated community and regulatory
agencies have met on numerous occasions and have exchanged comment letters,
including comment letters from outside scientists (Daniel Anderson, Donald
MacDonald and ten others), in addition to the report from the IAP. In this review, we
provide an analysis of the science underlying the organochlorine TMDLs for
Newport Bay and Watershed. Since organochlorines are regulated by the TMDL
process in many other locations, the analysis herein represents a case study that may
have application to other watersheds.
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