1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

SECTION 1
Introduction
This report presents the baseline Ecological Risk Assessment (ERA) for the Bolsa Chica
Lowlands. It provides a qualitative and quantitative evaluation of the actual or potential
effects of chemical stressors related to historical activities on aquatic, semi-aquatic, and
terrestrial biota (plants and animals) that inhabit or may use the Lowlands. The results of
the ERA will provide the information necessary for the state and federal resource agencies
to recommend no further action or remedial action at the project site. The objectives and
approach used to complete this report are described in greater detail in Sections 1.2 and 1.3.
The Bolsa Chica Lowlands are located in Orange County, California, (Figure 1-1) and
comprise about 1,200 acres of estuarine/marine and upland habitat. The Lowlands lie east of
the Pacific Coast Highway, between the higher elevation Bolsa Chica Mesa to the northwest
and Huntington Mesa to the east-southeast. Historically, the site and adjacent areas have been
used for agriculture, cattle grazing, as a wildlife refuge, and for recreational hunting and
fishing. However, since the 1920s, much of the area has been used for oil and gas exploration,
production, and processing. The earliest exploration occurred in the Edwards Thumb area
beyond the eastern tip of the Lowlands; oil operations in the Lowlands did not start until the
1940s (Klancher, 1999). The historical site activity as well as urban runoff draining into the
Lowlands has resulted in contaminating the plants and wildlife or their habitat.
The main focus of this project is to perform a baseline ERA for the Bolsa Chica Lowlands
(completed in this report) and to conduct a Confirmatory Sampling Program (CSP) (the final
phase of which will be completed after this ERA report in final). This work is being
conducted to characterize contamination within the Lowlands adequately and to help
establish clean-up criteria for portions of the property affected by previous activities,
primarily oil and gas production and urban runoff. It builds on previously available
information, including ecological and chemical characterization as well as the proposed
cleanup and restoration of the Lowlands.
The proposed restoration plan includes a mix of Full Tidal and Managed Tidal coastal
wetland habitats and non-tidal Seasonal Ponds (Figure 1-2). Once these habitats and ponds
are provided, more of the project site can eventually become a state or federal wildlife
refuge in addition to serving as mitigation for habitat losses elsewhere. Portions of the
Lowlands are currently managed as an Ecological Reserve by the California Department of
Fish and Game (including portions of Inner and Outer Bolsa Bay and the area delineated on
Figure 1-2 as “Non-tidal Portion of Ecological Reserve”). The rest of the project area is not
now managed as a wildlife refuge, but will be following site restoration.
The proposed restoration and anticipated future use of the Lowlands served as the focus of
the development of the ecological management goals for the site, which are:
• Sediment, surface water quality, and food source conditions capable of supporting
terrestrial, aquatic, and semi-aquatic plant and wildlife populations that would typically
be found in Full Tidal and Managed Tidal coastal wetland habitats, and non-tidal
Seasonal Ponds.
SAC/143368(001.DOC) 1-1 ERA REPORT
7/31/02