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 50

2 Newport Bay and Watershed

2.1 Location

The Newport Bay Watershed is centrally located in Orange County, California.
The 154-square mile Watershed includes portions of the cities of Newport Beach,
Irvine, Laguna Hills, Lake Forest, Tustin, Orange, Santa Ana, and Costa Mesa.
Runoff from the mountains that surround three sides of the watershed drains across
the Tustin Plain and enters Upper Newport Bay via San Diego Creek, one of two
major tributaries. Peters Canyon Wash, the other tributary, joins San Diego Creek in the
City of Irvine. These combined waterways drain 75,520 acres and are major con-
tributors of freshwater and sediment, and associated pollutants to Newport Bay,
which includes both Upper and Lower Newport Bay, as shown in Fig. 1 .

2.2 Climate/Hydrology

The area has a Mediterranean climate, with short, mild winters and warm dry summers.
Ninety percent of the precipitation occurs during November to April with an average
rainfall of approximately 13 in. per year. San Diego Creek has a wide range of water

Fig. 1 Newport Bay and Watershed. Figure 1-1 reproduced from U.S. EPA Region IX ( 2002 )