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 57

Table 2 DDT concentrations in the water column in Newport Bay and Watershed
Date Water body Sample location Fresh water fl ows Total DDT (ng/L) a

4/23/2001 Lower Bay Turning Basin Unspecifi ed 1.29

4/23/2001 Lower Bay PCH Bridge Unspecifi ed 1.04

3/12/2002 Rhine Channel NB3 Unspecifi ed ND

3/13/2002 Upper Bay NB10 Unspecifi ed ND

3/7/2002 San Diego Creek Campus Drive Dry weather ND

3/7/2002 San Diego Creek Campus Drive Storm ND

5/2/2002 San Diego Creek Campus Drive Dry weather ND

5/2/2002 San Diego Creek Campus Drive Dry weather ND

8/12/2002 San Diego Creek Campus Drive Dry weather ND

8/12/2002 San Diego Creek Campus Drive Dry weather ND

11/8/2002 San Diego Creek Campus Drive Storm 3

11/8/2002 San Diego Creek Campus Drive Storm ND

a Detection limit = 1.0 ng/L
ND is not detected
Bay et al. ( 2004 ) and Bay and Greenstein ( 2003 )

3.1.3 Water Column

Twelve water samples have been collected that characterize DDT concentrations
in the waters of the Newport Bay and Watershed, as shown in Table 2 . Accurate
measurement of the very low levels at which DDT is present in water in the Bay is
diffi cult, and only 3 of 12 data points, which were all collected in 2001 and 2002,
were above detection limits. For these reasons, no meaningful trend analysis could
be performed on concentrations of DDT in water. The California Toxic Rule (CTR)
human health regulatory threshold for DDT in water is 0.00059 ʼ g/L, or 0.59 ng/L

(US EPA Region IX 2000 ).

3.1.4 Fish and Mussels

A rigorous statistical analysis of DDT concentration data was conducted for three
different media: fi sh tissue, mussel tissue, and sediment. This analysis demonstrated
that DDT concentrations in red shiners and in mussels collected from San Diego
Creek, Upper Newport Bay, and Lower Newport Bay are declining in the watershed,
and that these trends are statistically signifi cant. DDT concentrations in seven other
fi sh species (for which too few data are available to conduct a robust statistical analysis)
are consistent with the trends observed in red shiners and mussels. The likelihood of
11 independent data sets showing a declining trend if a downward trend did not in
fact exist is 1 in 2 9 —i.e., vanishingly small.
Trends in DDT concentrations are evident in data collected for approximately
20 years in Newport Bay and Watershed. In the case of the fresh water fi sh species red
shiner, tissue DDT concentration data are available from 1983 through 2002 (n = 54);