EIR: Section 02 Purpose and Need SECTION 2 - PURPOSE AND NEED
2.1 Study Purpose and Need
The purpose of the feasibility study is to determine the Federal interest in measures to restore the
marine environment of Portuguese Bend Cove and adjacent areas. Due to the landslide movement
at Portuguese Bend, which has moved material 200-400 feet into Portuguese Bend Cove, the
previous marine habitat has been covered over with landslide debris and sediment eroded from the
shoreline by waves and tide, and nearshore and offshore areas have been impacted by siltation and
turbidity. The study's focus is on controlling the sedimentation and turbidity in the nearshore and
offshore zones that result from erosion at the shoreline, which impacts the marine biological
community of the area(see Fig. 2.1). (Also see Coastal Engineering Appendix - Volume II [Section
5.3].) The purpose of the restoration would be to restore natural hard rock reef in the nearshore (-10
to -30 MLLW) areas of the study area that are currently covered with landslide-generated sediment.
The purpose also is to eliminate the adverse impacts to the marine environment of the near constant
turbidity cause by lanslide sediment on existing nearshore kelp beds.
Prior to the 1950's, rocky reef areas and many intertidal pools were present along the shore and in
the nearshore area from Abalone Cove, around Portuguese Point and Inspiration Point, and through
Portuguese Bend to Bunker Point. The Portuguese Bend area is now silted and smothered to a lesser
or greater degree by landslide-generated sediment. Portuguese Bend supported a rich and diverse
marine flora(dominated by giant kelp) and fauna typical of Southern California intertidal and subtidal
• communities. Giant kelp and its associate understory of marine plants support a rich and diverse
assemblege of marine invertebrates and fish. This biological community is typically referred to as
the giant kelp forest community. Literally hundreds of marine invertebrate animals and more than 120
species of marine fish are known to occur in high quality kelp forests. (A detailed discussion of the
marine biological resources of the kelp forest is provided in section 4.2.2.) Unaffected kelp forest
of the Palos Verdes Peninsula serve as a graphic reminder of the diverse marine biological resources
that have been lost as a result of the extensive sediment and turbidity caused by the erosion of the
landslide bluff at Portuguee Bend. (See Wilson et al. 1980:85 & 90; Stephens, personal
observations cited in Pondella and Stephens 1998; Stephens 1990: pg. C-2-1; Pondella et al. 1996:61:
Bond et al. 1999:232& 235). (For information on the historic kelp canopy coverage on the Palos
Verdes Peninsula - see North 1983:150, Wilson et al. 1980:84; and Wilson and Togstad 1983-306).
As the vast majority of shallow marine substrates in southern California are unconsolidated sand or
mud (as much as 95 percent by an MBC 1988 estimate), soft bottom habitat is not a unique habitat-
type in the study area. Natural hard rocky reef, however, is an extremely rare, productive, and
valuable habitat-type. Natural hard rock habitat is so rare and valuable that California Department
of Fish and Game's (CDF&G) Marine Resources Divisions has a program to create and improve
artificial,reef habitat to augment the scarce natural reefs (see Carlisle et al. 1964, Lewis and McKee
1989, and CDF&G 1998). As natural rocky reef habitat is so rare and supports a large, diverse
assemblage of marine plants and animals, any effort to restore damaged or degraded natural reef
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habitat would be extremely beneficial to the marine biological community and is of great interest to •
resource agencies such as CDF&G and National Marine Fisheries Service (NMFS).
2.2 Study Objectives and Constraints
The primary objective of the feasibility study is to identify and recommend measures to control or
eliminate the sedimentation and turbidity caused by erosion of the shoreline berm which will result
in the restoration of the marine biological community associated with the natural hard rocky reef of
southern California. (Note that the objective is to restore natural hard rocky habitat and not to create
artificial reef habitat [also see section 3.4]).
This feasibility study does not attempt to address means to control the existing landslide at
Portuguese Bend No attempt was made to design a structure that would control or, in any way_ alter
the movement of the landslide. For this study it is assumed that the Portuguese Bend landslide will
continue throughout the life of the project and this constraint affected the design, construction,
potential habitat restoration, and cost of the proposed alternatives (see Section 3, below and Section
x'.1.2 of the Main Report). This uncertainty regarding the landslide extent, movement, and potential
for movement at the Portuguese Bend was considered in the design of the proposed concept plans
and limited the number of feasible alternatives that could be considered (see section 3.4)
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