1.1 MB pdf - Bolsa Chica Lowlands Restoration Project

Executive Summary
The Bolsa Chica Lowlands are located in Orange County, California and comprise
approximately 1,200 acres of estuarine, marine and upland habitat. Since the 1920s, much of
the area has been used for oil and gas exploration, production, and processing. The site and
adjacent areas have also been used for agriculture, cattle grazing, as a wildlife refuge, and
for recreational hunting and fishing. The historical site activity as well as urban runoff
draining into the Lowlands has resulted in contamination or physical disturbance of the
plants, wildlife or their habitat on the site.
This Ecological Risk Assessment was conducted in anticipation of proposed clean-up and
restoration of the Lowlands to a functioning estuarine system and to improve wildlife
habitat. It is anticipated that once clean-up and restoration activities are complete, the site
will become a state or federal wildlife refuge, as well as serving as mitigation for habitat
losses elsewhere. The anticipated future use of the Lowlands served as the focus for the
development of the ecological management goals for the site, which are as follows:
• 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
• Sediment, surface water quality, and food source conditions supportive of individuals
of special-status biota and migratory birds protected under the Migratory Bird Treaty
Act likely to be found in Full Tidal and Managed Tidal coastal wetland habitats, and
non-tidal Seasonal Ponds
As part of this restoration effort, the nature and extent of contamination on the site is being
investigated and evaluated. Two important elements of the investigation include an:
• Ecological Risk Assessment (ERA) (this document) to evaluate contaminants present at
the site at concentrations that present a risk to fish, wildlife or their habitat. The ERA
identifies exposure pathways and associated site-specific assessment endpoints. The
ERA also characterizes the ecological effects of the contaminants of concern. This and
other information and analysis in the ERA has been or will be used to (among other
things): (a) assess the nature of the contamination at the site and identify the general
areas of the site that contain contamination (b) assess the nature, characteristics, and
sensitivities of the natural resources at the site (c) determine the extent to which the
contamination threatens to impact natural resources at the site and (d) identify the types
or routes of exposure to the contamination that pose an unacceptable risk; and
• Confirmatory Sampling Program (CSP) to delineate the extent of on-site contamination
and the bounds of needed clean-up efforts. (The CSP was not completed at the time of
publication of this report.)
SAC/143368(ES.DOC) ES-1 ERA REPORT
7/31/02