DDT, Chlordane, Toxaphene and PCB Residues in Newport Bay and Watershed: Assessment of Hazard to Wildlife and Human Health - Reviews of Environmental Contamination and Toxicology - page 149

toxaphene gave the sediment OC concentration. Division by 100 gave the sediment
screening level at 1% OC. The K oc was assumed to be equal to a K ow value of
1,995 L/kg (log K ow = 3.3). Hence, the calculation of the screening level is
0.005

g/kg (ppb).
A specifi c reference for the log K ow of 3.3 could not be found in the New York
State Department of Environmental Conservation ( 1998 ) guidance document. The
K ow used by New York State is 158-fold lower than the K ow cited in the US EPA
Region IX ( 2002 ) and SARWQCB ( 2006 ) reports. Using the EPA and SARWQCB-
approved K ow value in the New York State method gives a sediment screening level
of 15.8 ppb.
The consequences of using the 0.1 ppb sediment target for toxaphene are major.
The SARWQCB ( 2006 ) report estimated a Newport Bay Watershed loading capacity
of 5.67 g of toxaphene per year and an existing load of 536 g of toxaphene per year.
Assuming these loads to be correct, there would have to be a 99% reduction in the
toxaphene load to meet the TMDL. Since almost all of the toxaphene is bound to
sediment, the sediment load reduction in the watershed would also have to be 99%.
A sediment load reduction of this magnitude would be impractical in a major storm
event. However, if one uses the 158-fold higher log K ow of 5.5 published by both the
US EPA Region IX ( 2002 ) and the SARWQCB ( 2006 ), the New York State sediment
screening level would increase 158-fold. The sediment target would then be 15.8 ppb,
resulting in a loading capacity of 896 g per year, a value greater than the estimated
existing load of 536 g per year, thereby obviating the need for a TMDL.

ʼ g/L × 1,995 L/kg × 0.01 = 0.1 ʼ

6 PCBs

The need for a PCB TMDL was stated by the SARWQCB ( 2006 ) in their report on
organochlorine TMDLs for Newport Bay and Watershed to be due to the level of
PCB residues in sport fi sh in Newport Bay exceeding guidance levels of 20 ppb
recommended by California EPA. This section will take a detailed look at the scien-
tifi c basis for the impairment analysis. The starting point is a review of the PCB resi-
due data in sport fi sh.

6.1 Levels in Sport Fish

The SARWQCB organochlorine TMDL report ( 2006 ) contains the PCB data
(Appendix A-1, Table 1) for sport fi sh that were relied upon by the SARWQCB in
their impairment analysis. The underlying data from the State Board is listed below
in Table 33 .
Of the 63 fi sh composites from 16 species of sport fi sh that were analyzed, 18
had measureable residues of PCBs. Two of these were at or below the reporting
limit of 5 ppb, leaving 16 composites above the reporting limit. Nine of the fi sh