2008 Annual Monitoring Report (pdf 10.9MB) - Bolsa Chica ...

Bolsa Chica Lowlands Restoration Monitoring
2008 Annual Report
INTRODUCTION
BACKGROUND
The Bolsa Chica Lowlands are located in Orange County, California, between Bolsa Chica Mesa on
the northwest and Huntington Beach on the southeast (Figure 0-1). In 1996, eight state and federal
agencies entered into an agreement to conduct wetland acquisition and restoration at the Lowlands.
Following project planning, land purchase, restoration design, permit acquisition, and publication of a
Final Environmental Impact Statement/Final Environmental Impact Report, restoration construction
began on October 6, 2004. The project involved the creation of a Full Tidal Basin (FTB) and
restoration of Muted Tidal Basins (MTB) by constructing an ocean inlet north of Huntington Mesa.
To create the FTB, approximately 1.57 million m 3 of material were excavated from within the Bolsa
Chica Lowlands to create a basin of a general depth of –1m NAVD, bounded by intertidal flats. The
excavated sand was distributed on the adjacent beaches from March to June 2006 (102,500 m 3 , divided
evenly to the north and south of the future inlet) as well as placed offshore from November 2005 to
May 2006 to form an ebb bar (929,326 m 3 ) outside of the future inlet. Approximately 531,354 m 3 of
material was placed to form the berms that bound the basin and three nesting areas. Remaining
material was hauled off-site. Jetties were constructed to form the ocean inlet to the basin from March
through June of 2006.
The FTB was opened to the ocean on August 24, 2006. The basin was designed to support 71.0
hectares (ha) (175.5 acres) of non-wetland waters, 49.6 ha (122.6 acres) of tidal flats, and 7.7 ha (19.1
acres) of pickleweed. In order to keep the inlet open, maintenance dredging is anticipated to be needed
every two to three years, with dredged sand to be placed on down-coast beaches.
Water control structures and culverts through the berm were installed to allow regular but muted tidal
influence from the FTB to each of three MTBs (Figure 0-1), to support 51.1 ha (126.3 acres) of salt
marsh habitat, and create 17.1 ha (42.3 acres) of tidal flats, 12.3 ha (30.5 acres) of cordgrass habitat,
and 0.7 ha (1.4 acres) of non-wetland waters. The west MTB was opened to tidal influence from the
FTB through its water control structure in March 2008, while the central and east basins remained
closed while additional oil spill and flood control protections were put into place. The restoration
project involved no changes to the Future Full Tidal Basin, which is currently an active oil production
field, or the Seasonal Ponds (Figure 0-1).
2008 SITE CONDITIONS
The water control structure at the west MTB was opened to tidal influence from the FTB on March 5,
08. The central and east remained closed, however several heavy rain events, slow seepage through
the control structures, and designed gravitational flow from the west to central MTB filled the low
lying areas of all three of the basins, creating open water in areas that were previously dry salt panne.
The storm events early in the year also raised the water level in Freeman Creek and the Seasonal
Ponds, creating large expanses of open water during many of the bird surveys. Because the water
control structures designed to drain Freeman Creek and Seasonal Ponds to the FTB were closed in
2008 while additional oil spill protections were put in place, water was pumped out of the creek and
some ponds in May 08 to lower the water level in the ponds to make more foraging habitat available
for western snowy plovers.
Merkel & Associates, Inc. 11