1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 2:PROBLEM FORMULATION
The entire interconnected marine/estuarine complex of Seal Beach NWR, Huntington
Harbour, and Bolsa Chica Lowlands (1,400 to 1,900 acres) receives stormwater runoff and
urban drainage from a total watershed area of approximately 48,000 to 50,000 acres
(Figure 1-1). Almost 18,000 acres of this watershed drain directly to the Garden Grove-
Wintersburg Flood Control Channel. The Lowlands also receive nonpoint runoff from
another 2,230 acres (CDFG/USFWS, 1976; CH2M HILL, 1994). Photos from the late 1940s
show drainage pathways bisecting the Lowlands from the east and southeast, draining into
Inner Bolsa Bay. The volume of urban runoff draining into the Lowlands has increased in
the last 5 years from several new residential developments in the uplands. Nutrients and
various contaminants—heavy metals, organophosphate pesticides, and organochlorine
herbicides—reaching the Lowlands from several of these sources are documented by Tetra
Tech (1996), and some of their probable impacts are described in Macdonald, et al. (1992).
Title to the Lowlands was transferred to the California State Lands Commission in February
1997. Funding by the Port of Los Angeles and Port of Long Beach will be used to construct a
new ocean inlet channel and subtidal basin that will be used to restore part of the existing
non-tidal wetlands ecosystem to Full Tidal condition (shown conceptually on Figure 1-2).
Development of these proposed restoration features will be overseen by the eight federal
and state agencies that have worked together to make the Bolsa Chica acquisition possible.
Full restoration of the Lowlands is planned to take place over 15 to 20 years. According to a
recent conceptual proposed restoration plan (Figure 1-2), while the Full Tidal, Managed
Tidal, and Seasonal Ponds habitats will be restored relatively soon, it may be 15 years or
more before the Future Full Tidal and Whipstock areas are restored. Construction phasing
for the proposed habitat restoration will, of course, involve the orderly consolidation and
ultimate removal of active oil field operations.
2.1.4 Previous Investigations
The Bolsa Chica Lowlands have a long history of potential contamination, hazardous waste
investigations, and site clean-up actions. Historical contaminant sources include lead shot
from Bolsa Chica Gun Club activities (1890-1964), but most contamination has come from
early operation and expansion of the Huntington Beach Oil Field (1920 to the present) and
from urban runoff and stormwater flows (i.e., Garden Grove-Wintersburg Flood Control
Channel, Springdale Pump Station, and Seacliff runoff) that have been diverted onto the site
(1940s to the present).
Several hazardous waste site contamination investigations have been conducted across
portions of the Lowlands and adjacent mesas (Figure 2-1), including the following:
• Woodward Clyde (1987)
• Groundwater Technology (1989)
• Earth Technology (1987, 1988, 1990)
• Schaefer Dixon Associates (1991)
• Tetra Tech (1996)
Key areas of concern in the Lowlands from the Schaefer Dixon Phase I Environmental
Assessment (1991) are shown on Figure 2-1. The principal non-aquatic areas of concern
more recently sampled during the Tetra Tech (1996) Phase II investigation are shown on
Figure 2-2, and Figure 2-3 shows sites with confirmed contamination.
ERA REPORT 2-4 SAC/143368(002.DOC)
7/31/02