Chapters 1 - U.S. Fish and Wildlife Service

Environmental Consequences
are identified that could reduce potential water quality impacts and they are also feasible,
practicable, and cost-effective, the discharger is required to implement the identified alternative
measures. One effective BMP identified in the General Permit is the use non-toxic and less toxic
controls. These include larvicides with very low toxicity that pose very little or no threat to the
environment. USEPA has concluded that microbial larvicides (e.g., Bacillus thuringiensis
israelensis, Bacillus sphaericus) do not pose risks to the environment; and methoprene, as used in
vector control programs, does not pose unreasonable risks to the environment (California State
Water Resources Board 2004). Therefore, the current vector control practices being conducted on
the Refuge are not expected to result in any adverse effects to water quality.
Public Use
The pathway that provides access for the public from the Refuge office/visitor contact station to
the observation deck consists of decomposed granite installed along a relatively flat surface. No
signs of erosion along the pathway are evident and the pathway continues to provide a firm and
stable surface, therefore, the continuation of the public use program currently conducted on the
Refuge would have little, if any, effect to water quality in the adjacent wetlands.
5.2.1.7 Effects from Climate Change/Sea Level Rise
Overview
Climate change, especially sea level rise, will significantly alter the existing conditions on the coast,
making coastal intertidal habitats, including the salt marsh habitat protected within the Seal Beach
NWR, some of the most at risk habitats in the world. As sea level rises, intertidal mudflats and
salt marsh habitat will be converted to subtidal habitat. In addition, decreases in precipitation
could adversely affect the health of the remaining cordgrass and other salt marsh vegetation that
depends on some seasonal freshwater input to promote plant vigor.
Although global sea level rise is well-documented, as described in Section 4.2.5.2, there are
currently no clear answers regarding how fast and to what extent sea level rise will impact these
existing habitats. This makes it difficult to establish specific long-term management strategies for
protecting this important habitat. We must instead rely on adaptive management to help us
identify measures to insure that coastal intertidal habitat and the wildlife it supports can persist at
some level as conditions change.
In an effort to better understand the potential effects of sea level rise on the habitat at the Seal
Beach NWR, the Service contracted the application of the Sea Level Affecting Marshes Model
(SLAMM) for the refuge. SLAMM 5.0.1, which accounts for the dominant processes involved in
wetland conversion and shoreline modifications during long-term sea level rise, predicts the
changes in tidal marsh area and habitat type as a result of sea level rise (Park et al. 1989;
www.warrenpinnacle.com/prof/SLAMM). The primary set of global sea level rise scenarios used
within SLAMM was derived from the work of the IPCC (IPCC 2001) and was run using the IPCC
and fixed-rate scenarios presented in Table 5-1. These scenarios, which include new information
related to assumptions of one meter and 1.5 meters of global sea level rise by the year 2100 (Chen
et al. 2006, Monaghan et al. 2006), indicate that global sea level may be rising progressing more
rapidly than was previously assumed. The A1B maximum (A1B Max) scenario incorporates the
suggestion by Rahmstorf (2007) that a feasible range by 2100 might be 50 cm (19.7 inches) to 140
cm (55.1 inches).
The SLAMM analysis for the Seal Beach NWR also incorporated a number of other factors
including: digital elevation mapping derived from LIDAR and ifSAR data from 2003 and 1998,
respectively; 2005 wetland boundary data from the National Wetlands Inventory; historic trends in
Draft Comprehensive Conservation Plan 5-7