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 City of Solana Beach
Section 3
Shoreline and Coastal Bluff Management Strategies Draft MEIR
Environmental Impact Analyses
a potential long-term degradation of recreational opportunities;
a substantial decrease in lateral beach access due to sand loss or reduction of the beach;
and
restricting existing public access or access structures (stairways).
3.4.2.2 Impact Assessment
Alternative 1 No Project - Continuation of Existing Policy
In general, impacts of shoreline protection structures to recreation and public access on
beaches are assessed by their potential to induce sand loss, or reduction of beach width in front
of a structure. Sand loss directly impacts public recreational opportunities by reducing the
amount of open space on the beach for recreational activities. Lateral access along the beach
is decreased as the amount of sand decreases and the beach becomes narrower. Public
access also includes stairways and ramps, which allow for beach access from inland areas and
the upper bluff. Some shoreline structures can be designed to help stabilize a stairway into the
bluff. Shoreline structures allowed under the No Project Alternative generally have no
significant impacts on stairways or ramps.
Impacts of protective shoreline structures on the beach have been a controversial issue
because different studies have opposing conclusions. Some studies, such as one conducted in
Monterey Bay (Griggs and others, 1994), conclude that no significant loss of beach occurs in
front of protective structures, such as a seawall, compared to the amount of sand loss in front of
unprotected areas. On the contrary, however, some studies, such as the SANDAG Preliminary
Technical Report, conclude the opposite, describing the potential for sand loss or beach width to
decrease as a result of shoreline structures (SANDAG, 1992). Although controversy remains
over the impacts of seawalls, it is important to assess the potential effects recognized in current
and ongoing studies. Based on the findings of these studies, shoreline structures, such as
those allowed under the existing Shoreline and Coastal Bluff Protection Ordinance, have the
potential to impact long-term recreational opportunities and lateral beach access, by reducing
the amount of sand on the beach in the following ways:
1.
Fixing the landward boundary of the beach. As the shoreline naturally retreats landward,
and the natural bluff face retreats at the same time, seawalls and other hard shoreline structures
built along an eroding bluff will not retreat. This impact is a gradual loss of beach in front of the
structure as the tide or shoreline continues to migrate landward, and sea levels continue to rise.
Passive erosion is also a consequence, which involves an increased rate of erosion to the
natural bluff adjacent to a seawall. An average long-term erosion rate of approximately 0.4 feet
per year, or 40 feet per 100 years has occurred at Solana Beach. Unlike seawalls or
revetments, seacave plugs and fills are designed to erode at the same rate as the bluff and are
required under the Shoreline and Coastal Bluff Protection Ordinance to prevent this process.
However, seacave plugs and fills are not always effective and may not erode as rapidly as the
adjacent bluff. Therefore, fixation of the landward beach boundary results in potential long-term
loss of beach width and recreational opportunities and is considered a significant impact to
recreation.
Project No. 323530000
Page 3-52
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