«DRAFT ENVIRONMENTAL ASSESSMENT ENVIRONMENTAL ASSESSMENT FOR THE COLUMBIA STOCK RANCH SECTION 536 ECOSYSTEM RESTORATION PROJECT The environmental ...»
These changes would not be spatially homogeneous across the Columbia River. Rather, areas with elevations high enough to maintain temperatures well below freezing for most of the winter and early spring would be less affected than low-lying areas historically receiving little precipitation and contributing less to total stream flow. Overall, about one-third of the current cold-water fish habitat in the Pacific Northwest is likely to exceed key water temperature thresholds by the end of this century (USGCRP 2009). Precipitation trends during the next century are less certain than for temperature, but more precipitation is likely to occur during October through March and less during summer months and more winter precipitation is expected to fall as rain rather than snow (ISAB 2007, USGCRP 2009). Where stream flows are unregulated, the Columbia River freshet is expected to occur three to four weeks sooner (Snover et. al, 2013).
April 22, 2016 Page 47 The earth’s oceans are also warming, with considerable annual and decadal variability superimposed on the longer-term trend. Historically, warm periods in the Pacific Ocean have coincided with relatively low abundances of salmon and steelhead, while cooler ocean periods have coincided with relatively high abundances (USGCRP 2009). Evaluation of future sea level rise is outlined in Corps guidance (Engineering Circular 1165‐2‐212 [USACE 2011]).
The regulations prescribe a method for defining three future projections of sea levels (lowest, expected, and highest) that are used to bound the estimate for sea level rise over time. The sea level projections (curves) are site specific and are derived based on the historical sea level trend (the local sea level change) blended with the eustatic change (the change in sea level due to changes in either the volume of water in the world oceans or net changes in the volume of the ocean basins). Curve #1 defines the lowest expected bound for sea level rise; Curve #2 defines a prudent expected trend; and Curve #3 defines the highest expected bound.
The sea level projections shown in Figure 9 are based on sea level data from the National Ocean Service Station at Astoria, Oregon. Based on the Corps analysis of potential climate change, the degree of sea level change that may affect the CSR project site (RM 76.5) over the planning horizon (50 years, 2018 to 2068) could increase tidal water level elevations by 0 feet, 0.26 feet, or 1.32 feet, depending upon which of the three curves is applied.
Environmental Consequences No Action Alternative Climate change is widely recognized as a critical issue with potentially wide-ranging effects on water resources, fish and wildlife species and their habitats, and other natural resources. It has April 22, 2016 Page 48 also been suggested that the effects of climate change will exacerbate temperatures, the timing and magnitude of stream flow, habitat loss, isolation and degradation, invasive species, and drought. According to the USGCRP, the average regional air temperatures have increased by an average of 1.5°F over the last century (up to 4°F in some areas), with warming trends expected to continue into the next century (2009).
The effects of climate change under the No Action Alternative may result in changes in temperature, precipitation, and sea levels at the CSR project site. As described, the annual mean temperatures in the lower Columbia River are likely to rise through the end of century (an increase of anywhere from 3 to 10° F). Seasonal variations are likely to result in summertime warming to be greater than the current mean annual temperatures. Furthermore, precipitation patterns are likely to change in the Columbia River watershed (from the source to the mouth and all contributing watersheds). Annual precipitation amounts would likely be about the same; however, winter and fall would likely be wetter and summer times would be drier. The Columbia River flow regime would also likely change, wherein forecasts predict unregulated freshets could arrive on average four weeks earlier. Intense hydro-regulation of the Columbia River makes anticipating the exact form and duration of future freshets difficult to estimate.
In general, conditions within the study area are not anticipated to appreciably degrade during the period of analysis, nor are they expected to markedly improve. However, the indirect effects of these actions on resources in the CSR project vary and include higher winter stream flows, impacting sensitive watersheds and fish and wildlife. Earlier peak stream flows could alter the duration and frequency of seasonal inundation and incidental flooding from the Columbia River. Invasive species would persist throughout the site. Lower stream flows and warmer water temperatures during summer would further degrade conditions for aquatic wildlife during the summer months when water is scarce. Poor water quality conditions could increase the prevalence and virulence of fish diseases and parasites (USGCRP 2009). Other adverse effects are likely to include altered migration patterns, accelerated embryo development, premature emergence of fry, variation in quality and quantity of aquatic habitats, and increased competition and predation risk from warm-water, non-native species (ISAB 2007).
Proposed Action The Corps’ guidance indicates that projects should incorporate the direct and indirect physical effects of future sea level change across the life cycle of the project. The Corps conducted an analysis of climate change impacts under the Proposed Action and comparisons between the No Action Alternative and the Proposed Action indicate that climate change impacts would be very similar; however, implementation of restoration features provide an overall net benefit and increases the resilience of fish and wildlife habitat experiencing changing climatic conditions. Overall, potential sea level rise would increase the spatial extent of inundation on the CSR project site, increasing opportunities for rearing and foraging habitat, damping adverse impacts to water quality, and increase water storage capacity of wetland features.
Due to their dependence on groundwater exchange and surface water connection, wetlands in the CSR project site are sensitive to changing water levels in the Columbia River. A rise as minimal as a 0.5 foot in elevation has the potential to impart rapid successional changes to fringe and shoreline habitat. However, due to the complexity of the interactions, it is difficult to quantify the future effects. Potential effects from increased water depth (which increases the potential area of inundation throughout the CSR project site) include changes in velocities April 22, 2016 Page 49 during the tidal cycle, the duration of inundation, water circulation across the site, water temperatures in tidal channels during low flow conditions and sediment loads.
Physical changes in water surface elevations could indirectly affect fridge habitat, altering the quantity of wetland and shoreline habitats, indirectly affecting nutrient availability, foraging opportunities, refugia from increased temperatures and predators. Despite these potential impacts, it is assumed that any adverse effects that climate change might have across the project area during the planning horizon would be negligible and effects to any aquatic or terrestrial habitat would less than when compared to the No Action Alterantive described above.
5. CUMULATIVE EFFECTS This section analyzes the potential cumulative impacts that may occur following implementation of the Proposed Action when considered with other past, present, and reasonably foreseeable future actions. Cumulative effects are defined as, “the impact on the environment which results from the incremental impact of an action when added to other past, present, and reasonably foreseeable future actions regardless of what agency (federal or nonfederal) or person undertakes such other actions” (40 C.F.R. § 1508.7). Cumulative impacts can result from individually minor actions, but which can collectively have a measurable impact over a period of time in a specific geographic area.
Noting that environmental impacts may result from many diverse sources and processes, CEQ guidance observes that “no universally accepted framework for cumulative effects analysis exists,” while noting that certain principles have gained acceptance and “the list of environmental effects must focus on those that are truly meaningful.” Considering Cumulative Effects Under the National Environmental Policy Act (CEQ 1997). Assessing cumulative impacts may involve assumptions and uncertainties because data on the environmental effects of other past, present, and reasonably foreseeable actions are often incomplete or unavailable. As a result, impacts on resources often must be expressed in qualitative terms or as a relative change. For this analysis, potential cumulative impacts were assessed using guidance from CEQ.
The proposed temporal boundary for analyses of cumulative impacts is the early 1900s, when authorization and construction of the Columbia River Levee occurred and to the extent that it has had lasting effects contributing to cumulative impacts of the CSR project site. The reasonably foreseeable nature of potential future actions helps define the forward-looking temporal boundary. While ongoing restoration activities in the Columbia River could continue for many more years and could contribute to cumulative impacts during that timeframe, it would be speculative to consider actions beyond what is reasonably foreseeable. Given this limitation, the forward-looking temporal boundary has been established at 2 years, which is a reasonable timeframe by which the future actions could be anticipated and completed relative to the Proposed Action.
The geographic boundaries and cumulative effects vary for each resource, but the boundary for this analysis has been limited to the Columbia River adjacent to the project area between Kalama, WA and St. Helens, OR. Analogous to the resources evaluated in Chapter 4, only those resources which could reflect a measurable, cumulative impact in the Columbia River watershed were evaluated in this analysis. Resources excluded from analysis include: geology, topography, soils, air quality, and noise. Furthermore, this analysis uses the same measurable threshold(s) to assess the social and environmental impacts for both the No Action Alternative April 22, 2016 Page 50 and the Proposed Action. In general, effects of a particular action or group of actions would be
considered to have a measurable cumulative impact if one of the following conditions are met:
Effects of several actions occur in a common location;
Effects are not localized and contribute to effects of an action in a different location;
Effects on a particular resource are similar in nature or affect the same specific resource element; and Effects are long-term or permanent.9 It should be noted that this EA used a framework for assessing cumulative effects, and relied upon assumptions and uncertainties because specific data on the environmental effects of other past, present, and reasonably foreseeable future actions is often incomplete or unavailable. As a result, the potential impacts on resources are expressed in qualitative terms or as a relative change from current conditions.
5.1. Past Actions The CEQ issued a memorandum on June 24, 2005 regarding analysis of past actions. This memorandum states, “agencies can conduct an adequate cumulative effects analysis by focusing on the current aggregate effects of past actions without delving into the historical details of individual past actions” (CEQ 2005). Past actions relevant to the cumulative analysis in this document are those that have previously taken place and are largely complete, but that have lasting effects on one or more resources that would also be affected by implementing the Proposed Action. For these past actions, CEQ guidance states that consideration of past actions is only necessary to better inform agency decision-making. Typically, the only types of past actions considered are those that continue to have present effects on affected resources.
Past actions are summarized below and their effects, which have resulted in the existing conditions, as described in Section 5.4.
Construction, maintenance and periodic reconstruction of pile dikes, levees, and bridges in, over, or adjacent to the Columbia River between RM 70 and 80;
Construction and on-going maintenance dredging of the Kalama Turning Basin for the Port of Kalama Continued use, maintenance, and operation of the FCRPS multi-purpose dams in the Columbia River and Willamette River basins;
Continued human use and modification of the Columbia River estuary, the surrounding area, and tributaries feeding into the river up until the passing of the CWA. This included clearing for timber harvest and agricultural development, urban development of towns and cities near the shoreline, highways and railroads, and power and utility lines; and, The Corps’ annual maintenance dredging and placement activities associated with the Columbia River Federal Navigation Channel.
By definition, short-term impacts tend to dissipate over time and cease to contribute to the cumulative effects as the effects subside or become inconsequential.
April 22, 2016 Page 51 The existing conditions in the Columbia River watershed include the past construction and current operation and maintenance of dams and reservoirs along the entire river. This construction fundamentally changed the character of the watershed, moderating flood flows during the winter by strategically storing and releasing water to minimize flooding. In addition to flood control, the dams and reservoirs function maintain downstream flows throughout the summer via the strategic release of water to supplement downstream inflows. Specific to the CSR project site, construction of flood protection levees and drainage channels altered interaction of river flows with the project site and anthropogenic site use (agriculture and cattle grazing) introduced non-native species which have become widely established and dominate the vegetation communities.