Chapters 1 - U.S. Fish and Wildlife Service

Chapter 5
Hydrology – An adverse hydrologic effect is considered significant if an action would result
in increased storm and/or tidal flooding on- or off-site, a net deficit in the aquifer volume, a
drop in the local groundwater table, or changes in tidal circulation that would trigger or
accelerate slope/bank instability or erosion affecting facilities located both on and off the
Refuge.
Water Quality – Adverse impacts to water quality would be considered significant if the
action would violate any water quality standards or waste discharge requirements,
substantially increase sedimentation or turbidity in adjacent tidal waters, introduce
contaminants (non-point source pollution) into the watershed, or otherwise substantially
degrade water quality.
Climate Change/Sea Level Rise – Although the proposals described in this document
would have no influence over climate change or sea level rise, changing conditions
associated with climate change and sea level rise could adversely affect Refuge resources
or influence future Refuge management. The predicted effects of climate change and/or
sea level rise could be significant if these effects would substantially alter or degrade
sensitive habitats that support listed species, migratory birds, or other species of concern.
In addition, effects of climate change and/or sea level rise would be considered significant if
Refuge property, such as structures, trails, roads, signage, and other facilities, could be
damaged or destroyed as a result of changing site conditions, including increasingly severe
weather conditions.
Air Quality – Direct adverse effects related to air quality would be considered significant if
the action would result in emissions equal to or in excess of the NAAQS; sensitive
receptors are exposed to substantial pollutant concentrations, including air toxics such as
diesel particulates; or air contaminants are released beyond the boundaries of the Refuge.
Significant indirect effects to air quality would occur if a proposed Refuge action results in
the degradation of the existing level of service on adjacent roadways. Significant
cumulative effects would occur if the “de minimis” (minimum) thresholds developed by the
EPA for proposed Federal actions in a non-attainment area are exceeded.
Greenhouse Gas Emissions – The Service has not developed a quantitative threshold for
determining whether a project’s greenhouse gas (GHG) emissions will have a significant
effect on the environment and no statewide threshold has been adopted by the State of
California. The California Air Pollution Officers Association (CAPCOA) in its publication
“CEQA & Climate Change: Evaluating and Addressing Greenhouse Gas Emissions from
Projects Subject to the California Environmental Quality Act” (2008) does explore various
options for establishing significance thresholds for GHG emissions. These options include
setting the threshold at zero and setting a non-zero level for GHG emissions. Another
option involves addressing project effects without establishing a threshold. This could be
accomplished through a quantitative or qualitative evaluation of individual projects.
Because significance thresholds for GHG emissions have yet to be established, our
significance determination is currently based on the specific context of an individual action.
To the extent possible, our determination is based on a quantitative evaluation of the
effects of the action’s GHG emissions on the environment, including an estimate of the
expected GHG emissions, and the extent to which efforts are made to reduce expected
emissions.
5-2 Seal Beach National Wildlife Refuge