Corps of Engineers Centralia Flood Damage Reduction Project Chapter 5 September 2002

5. Cumulative Impacts

5. Cumulative Impacts

5.1 Introduction

The combined, incremental effects of human activity, referred to as cumulative impacts, pose a serious threat to the environment. While they may be insignificant by themselves, cumulative impacts accumulate over time, from one or more sources, and can result in the degradation of important resources. Because Federal projects cause or are affected by cumulative impacts, this type of impact must be assessed in documents prepared under NEPA.

Cumulative impacts result when the effects of an action are added to or interact with other effects in a particular place and within a particular time. It is the combination of these effects, and any resulting environmental degradation, that should be the focus of cumulative impact analysis.

While impacts can be differentiated by direct, indirect, and cumulative, the concept of cumulative impacts takes into account all disturbances since cumulative impacts result in the compounding of the effects of all actions over time. Thus the cumulative impacts of an action can be viewed as the total effects on a resource, ecosystem, or human community of that action and all other activities affecting that resource no matter what entity (Federal, non-Federal, or private) is taking the actions.

Cumulative impact analyses typically review historic impact, current conditions and reasonably foreseeable future impacts. In the following sections, historic, current, and reasonably foreseeable conditions are summarized for the study area and then examined in relationship to the preferred alternative and its potential to result in cumulative impacts to each subject area (biological resources, cultural resources, etc.)

5.1.1 Historic Impacts to the Study Area

The study area experienced various forms of development since the mid-19th century.

Development activities included extensive logging, diking, road and highway construction, navigational improvements, damming, grazing, agriculture, and residential and commercial development.

The most dramatic changes to the Chehalis River occurred during aggressive efforts by the Federal Government to improve the navigability of the river in the late 1800s and early 1900s (for example, see Secretary of War 1890). This included the removal of snags, overhanging trees, log jams, drift heaps, shoals, and other obstructions to navigability. In 1 year (1887), 293 large snags were removed from the main channel, beginning at Claquato and ending near Oakville (approximately 16 miles), and masses of log drifts and log jams were loosened or burned (Secretary of War 1887). The practice of removing woody obstructions continued for decades through this reach for purposes of floating logs generated by timber operations (Secretary of War 1892, Wendler and Deschamps 1955).

Logging development also made dramatic changes to the study area. The earliest logging dams were built in the 1880s and continued through the 1920s. Splash dams were built on Elk Creek, Hope Creek, Chehalis River, South Fork Chehalis, Deep Creek, and the Skookumchuck River.

The length of time that the dams remained in the streams ranged from less than 1 to more than 50 years, with an average of about 20 years. All splash dams were removed, washed out, or burned prior to 1944 except for one splash dam that may remain intact on Elk Creek (as of 1955) (Wendler and Deschamps 1955).

Splash dams were intentionally destroyed to carry logs downstream, a process termed "splashing." This process significantly affected channel dynamics. The floods of logs and water scoured or moved the gravel bars, leaving only barren bedrock or heavy boulders (Wendler and Deschamps 1955). New channels were created in some areas and/or changed the geometry (width, depth, cross-section shape) of existing channels. Splashing occurred on the average of once each week, but in some cases once a day. If the sudden influx of logs into a stream below the dam caused a log jam, dynamite or black powder was used to clear the obstruction (Wendler and Deschamps 1955). Natural logjams were removed in the process as well. The lack of logjams and the scour from splash dams has resulted in a simplified stream system in which water and sediment is routed much faster than prior to basin settlement.

Logging and agricultural development resulted in clearing of vast areas of native vegetation, including wetlands and riparian areas as well as upland forests. Much of the historic wetland area in the Chehalis Valley had drainage tiles and/or ditches or both constructed to facilitate agricultural use. Many of the riparian areas were either logged or cleared to open more area for agricultural or residential and commercial development.

Most of the residential and commercial development has occurred around the Cities of Centralia and Chehalis. These two cities occupy portions of the floodplain, while their associated infrastructure crosses the river, its tributaries, and their floodplains.

As the population of the area increased over time, the surrounding floodplain experienced a relative increase in the amount of development pressure. Residential and agricultural developments occurred within flood-prone areas to accommodate the increased population.

These newly developed areas required transportation corridors and other infrastructure, as well as commercial businesses to support them. As a result, damage to buildings and infrastructure from flooding increased as development of the floodplain proceeded.

The road system in the study area developed in response to population increases and the establishment of farms, residential areas, industries, and commercial businesses in the mid to late 1800s. Land uses and the transportation system built to serve these uses were influenced by the opportunities and constraints presented by natural land features, including steep slopes, rivers and streams, and floodways. Rail lines were constructed to transport the agricultural commodities, timber, and lumber produced in the area, and subsequent patterns of industrial and commercial growth were largely determined by the locations of the rail lines and depots.

Interstate 5 was later constructed along the general corridor established by the rail lines. The construction of Interstate 5 included the relocation of the lower portion of the Skookumchuck River.

Flooding of roadways and rail lines was historically a problem in large portions of the study area; for example, photographs of downtown Centralia taken in the early 1900s show vehicles axledeep in floodwaters. Flood damages the area increased as more development occurred in the floodplain.

The changes brought about by navigation work, logging, agriculture and residential and commercial development had a significant impact on the biological resources of the study area.

The major impacts included:

Loss of wildlife habitat. Clearing of native vegetation and the construction of major transportation corridors virtually eliminated large mammal populations from the area.
Remaining wildlife habitat is scattered in a scattered areas around the floodplain and no longer provides pathways for animal migration.
Loss of fishery habitat. The Chehalis River once supported a complex aquatic community, including anadromous and resident fish species. Back channels, braided channels, shallow gravel beds, and pool and riffle complexes allowed for highly productive habitats. Navigation work and land use practices resulted in altered hydrology and sediment transport into streams and rivers and a reduction in biodiversity to the detriment of fish spawning and rearing habitat. The clearing of wood jams and snags from the Chehalis River (including the tributaries) and changed the fish habitat creation and nutrient retention patterns within the floodplain. The influence of woody debris jams on the creation of off-channel and other rearing habitat had been similarly reduced.
Loss of wetlands and riparian areas. Clearing of wood jams and snags from the Chehalis River system (including the tributaries) also changed the flooding and ponding patterns within the floodplain, which reduced the extent of wetlands and riparian areas. Wetlands were also drained throughout the study for agriculture and filled for development.

Riparian areas were logged and cleared for both agricultural and development purposes.

This resulted in losses of fish and wildlife habitat, decreases in water quality, loss of floodwater retention and detention, and loss of low flow augmentation to the Chehalis River and its tributaries.

Loss of native vegetation. Grazing and clearing of the native prairies (as well as clearing in other habitat types) resulted in a loss of biodiversity and habitat.

Loss of migration corridors for plant and animal species. Construction of major features such as Interstate 5 and development of the floodplain resulted in the fragmentation and isolation of habitat. This essentially created islands of habitat and plant populations. The result of this is the outright loss of plant and animal species or much smaller populations of both. This has reduced both the biodiversity and the ecological health of the entire basin ecosystem.

The principle pathways of the impacts identified above are: (1) modification of the waterways; (2) modification of the floodplain; (3) agricultural and sivicultural practices; and (4) the development of urban centers and major transportation corridors.

5.1.2 Current Condition in the Study Area

Current conditions in the study are largely a result of the historic changes to the Chehalis River system. Although the majority of the Chehalis River floodplain remains in agricultural use, the severity of floods in the area appears to be increasing, and flood damages have risen significantly. As recorded at the Grand Mound gage, the February 1996 and January 1990 floods represent the first and second highest floods, respectively, observed in the Chehalis basin since 1929. Six other major floods occurred in the past decade. These include the third and sixth highest floods of record, which occurred in November 1986 and November 1990, respectively.

Because the Skookumchuck confluence was relocated to its present location, the additional water raises the water surface within the Chehalis River downstream of the confluence and creates a backwater effect upstream of the confluence.

The floodplain currently shows numerous oxbows and other features formed by cutoff of meander bends. Aerial photographic analysis indicates that these features formed sometime before 1949 (earliest available aerial photographs of the study area) and have changed little in the past 50 years. These features are not ancient, and are likely no more than a few hundred years old. Given the extremely low gradient of the channel and floodplain through the study area, the oxbows present on the floodplain can be interpreted as features that were formed during a period when large woody debris (LWD) was abundant within the Chehalis River. LWD probably caused the formation of side channels and oxbows. This is supported by the observation that no new oxbows or channel features have formed in the past 50 years even though the basin experienced several large flood events.

The study area still plays an important ecological role because it continues to be support remnant forest, prairie, riparian and wetland ecosystems as well as providing support for fisheries and wildlife. Current practices of development and land use include modification of the floodplain through development and on going agricultural and silvicultural practices. These would likely continue to diminish beneficial functions associated with the remnant ecosystems.

Current land uses in the study area are composed primarily of residential, agricultural, and silvicultural uses, although commercial and light industrial uses have been increasing in recent years. Commercial development has been focused primarily along the Interstate 5 corridor in Centralia and Chehalis. Improvements to transportation corridors in the area are ongoing. The area is expected to continue to undergo development in accordance with locally adopted comprehensive plans.

Portions of I-5 are subject to inundation during large flood events, which has resulted in the multi-day closure of the freeway between Chehalis and Centralia. Primary arterials, including all north-south roads between Chehalis and Centralia, are also inundated with floodwaters during larger floods. Flooding has accelerated the deterioration of the substructure of some arterial routes in the area, causing damage to the roadway sub-base and pavement (City of Chehalis, 1999). Larger floods also cause portions of the rail lines to become temporarily unusable when the subgrade becomes saturated or the rail lines are overtopped by floodwaters.

5.2 Reasonably Foreseeable Impacts to the Study Area

Residential, commercial, and industrial development within flood-protected areas would continue, primarily within designated urban growth boundaries in and around Chehalis and Centralia. This development would increase the extent of impervious surfaces, resulting in additional runoff and decreasing groundwater recharge in these areas. Management of stormwater runoff from developed areas would be subject to local and State guidelines and requirements. The effects of a decrease in groundwater recharge from these areas are expected to be minor, as they represent a relatively small portion of the overall basin, and are generally located on fine-grained soils with low infiltration rates.

The Washington State Department of Transportation (DOT) is currently evaluating traffic improvements to I-5, which may include widening of the freeway and the reconstruction of existing freeway exit and entering ramps. There is no timetable for these actions but are likely to be proposed within the next 5 to 10 years. These improvements would potentially impact the land use adjacent to the freeway and the interchange areas. Lewis County is also sponsoring a proposal for new interchanges and connections to the local road system in the vicinity of the existing LaBree Road overcrossing and in north Lewis County. The local jurisdictions would continue to develop maintenance, safety and capacity improvements, and street extensions as part of their comprehensive and capital improvement planning activities.

Relocation of the municipal sewage treatment plant is foreseeable in the next 5 years and changes in operation at the PacifiCorp Steam plant may alter needs for Skookumchuck River withdrawals.

The Corps of Engineers in partnership with Grays Harbor County has begun study of the entire Chehalis basin (Chehalis Basin Ecosystem Restoration Project). The purpose of this study is to select a myriad of project alternatives, which both recover the degraded ecosystem, primarily for salmonid recovery, and provide ancillary flood damage reduction benefits to the basin. This is in addition to and inclusive of watershed management planning and analysis currently underway by State and local agencies within the basin.

The study includes intensive public and agency involvement with the purpose of selecting projects that will benefit to goals of ecosystem restoration with ancillary flood damage reduction.

The current understanding is that the selected projects would be implemented over a 10 to 15 year period.

5.2.1 Cumulative Impacts Associated with the Preferred Alternative

5.2.1.1 Hydrology and Hydraulics

The preferred alternative would result in little change to flooding within the active portions of the Chehalis River floodplain and its tributaries. Significant changes to the extent of flooding in the Chehalis River valley would occur only during large floods. Areas that would be prevented from flooding are generally not within the active floodway, but instead are backwater or temporary storage areas where short-duration flooding occurs. Modifications to the Skookumchuck Dam and reservoir operations would eliminate large overtopping floods on the Skookumchuck River and replace them with smaller events of greater frequency and duration.

Substantial increases in flood stage or flow velocities within and upstream or downstream from the study area are not expected. The preferred alternative would have no significant effect on

recharge of groundwater resources. The long-term changes associated with development of the basin would continue to dominate the hydrology and hydraulics of the Chehalis River system, and would be little affected by project implementation. Mitigation actions associated with the preferred alternative would reconnect portions of the Chehalis River to the adjacent floodplain.

These actions would be expected to enhance local groundwater recharge associated with minor (1 to 2-year) floods.

The preferred alternative would alter flood stages and timing of flows in the study area and potentially could contribute to the cumulative effects of past hydrologic and hydraulic modifications. Future development in areas that would be protected from flooding would result in changes in runoff and infiltration. However, design considerations incorporated into the preferred alternative would avoid unnecessary impacts, minimize unavoidable impacts, and provide mitigation to offset potential impacts and restore some historic functions of the Chehalis river floodplain. No specific information is available on likely future development, including improvements to Interstate-5, however, these projects would also be rigorously analyzed for impact avoidance and minimization. No significant cumulative impacts to hydrology and hydraulics are expected.

5.2.1.2 River Geomorphology

The anticipated effects on river geomorphology in response to predicted changes in hydrology and hydraulics are negligible. The long-term channel changes associated with the historical removal of LWD and the relocation of the Skookumchuck River confluence would likely continue unaffected by the preferred alternative. While there is currently a very limited source of LWD along the Chehalis River within the study area, the preferred alternative allows for the future establishment of a restored riparian zone that could supply LWD to the channel through bank erosion and channel migration in the future. No specific information is available on likely future development, including improvements to Interstate-5, however, these projects would also be rigorously analyzed for impact avoidance and minimization. No significant cumulative impacts to river geomorphology are expected.

5.2.1.3 Cumulative Impacts on Water Quality

Construction of the project in the Chehalis River watershed have the potential to cause temporary and intermittent increases in suspended solids or concentrations of biostimulatory nutrients (nitrogen and phosphorus) in the Chehalis River (and tributaries) for those portions of the project that are located in close proximity to the river and tributaries; the major portion of the levee and floodwall alignment is setback away from the river and tributaries. Any soil-disturbing activities during construction would be conducted in compliance with State approved construction stormwater management plans. Past impacts have resulted in the majority of the concurrent water quality concerns (specifically, seasonal high temperatures and low dissolved oxygen).

This project is not expected to degrade the current condition. Impacts from the preferred alternative is not likely to result in significant cumulative impacts to water quality as a result of construction.

After construction, the preferred alternative would have limited potential for impacts to water quality because of its setback location. The preferred alternative would not change normal flows or velocities of the river and tributaries, would not degrade existing conditions by being a source of contaminants, and/or would not result in changes to temperature, turbidity, and dissolved oxygen conditions. There would be some changes in the duration of larger magnitude floods within the Chehalis Valley study area, which may result in increased sedimentation, scour, and bank erosion. However, it would be difficult to differentiate specific impacts associated with the preferred alternative because of the catastrophic nature of the flood itself. The preferred alternative may result in cumulative impacts to water quality during the flood events, but this would be episodic in occurrence and likely of short duration. As stated above, past impacts have resulted in the majority of impacts to water quality and the preferred alternative will not degrade the existing condition. As such, no significant cumulative impacts to water quality as a result levees and floodwalls in the Chehalis Valley and lower Skookumchuck River are expected.

Changes to the operation of the Skookumchuck Dam, which would result in changes to frequency and duration of floods on the Skookumchuck River may result in cumulative impacts to water quality. Specifically, changes in the frequency of lower magnitude floods (5- and 10- year events) may change beneficial uses associated with riparian and wetland habitats. The major impacts associated with the Skookumchuck River have occurred from past actions, however, changes in operations may affect the current condition. This potential impact would be further evaluated during design.

No specific information is available on likely future development, including improvements to Interstate-5. However, water quality on the Chehalis River is of concern to both State and local agencies and these projects would also be rigorously analyzed for impact avoidance and minimization.

Proposed mitigation plans for the preferred alternative, which include increased canopy cover and wetland creation and restoration should decrease summer water temperatures and improve dissolved oxygen conditions during low flow periods in the Chehalis River. These actions are intended to improve baseline conditions of the river. This action may help restore some of the historic functions of the Chehalis.

5.2.1.4 Biological Resources - Vegetation, Wetlands, and Riparian Areas

The preferred alternative would result in modification Skookumchuck Dam and the modification of the floodplain through the construction of the levees and floodwalls. The floodplain modifications have been focused on avoiding unnecessary impacts to critical habitats (wetlands and riparian areas). The major impacts to wetlands and riparian areas occurred as a result of past actions. No information is available to evaluate the extent of future actions, although future projects, including Interstate 5, are likely to result in wetland losses. Compensatory mitigation for the preferred alternative would increase the function and extent of wetlands and riparian areas as well as increasing the overall vegetation biodiversity in the project area and may serve to offset cumulative impacts as well as restore some historic functions. Future development that includes impacts to biological resources would likely require avoidance, minimization, and compensation measures. What remains unknown is the potential impacts to the wetland and riparian areas of the Skookumchuck River from the change in operation of the Skookumchuck Dam. However, the potential for cumulative impacts would be associated with the first reach between the dam and the first tributary. This reach is the only reach that a modified dam would have direct and cumulative impacts.

5.2.1.5 Biological Resources - Wildlife

The preferred alternative would result in the loss of land that could be potentially modified into habitat for wildlife, both within the alignment footprint and on the levees. In order for the levees to maintain their structural integrity, woody vegetation would be regularly removed thus reducing the potential use as wildlife habitat.

The proposed mitigation would increase the habitat for wildlife by creating additional riparian habitat, connecting oxbows, creating and restoring wetlands. This would restore some of the historic habitat for smaller wildlife species, although it would not restore habitat for larger species such as elk and deer. The major impacts from connectivity issues associated with the transportation corridors and development of the floodplain use are too large to be overcome by the preferred alternative, however, the project will not result in any degradation of existing conditions. No information is available on the extent of potential future actions, but these actions would be subject to avoidance, minimization, and mitigation requirements. No significant cumulative impacts to wildlife are expected.

5.2.1.6 Biological Resources - Fish

The preferred alternative would result in modification Skookumchuck Dam and the modification of the floodplain through the construction of the levees and floodwalls. The floodplain modifications have been focused on avoiding unnecessary impacts to critical habitats (wetlands and riparian areas). The majority of impacts to fisheries are associated with past actions (floodplain modification and development, removal of LWD, habitat modification, etc). The preferred alternative would not result in any degradation of existing conditions within the Chehalis River floodplain. Compensatory mitigation would increase biodiversity, improve fish habitat, increase primary and secondary productivity, and increase flood storage opportunities, which would restore some of the historic function. No information is available on the extent of potential future actions, but these actions would be subject to avoidance, minimization, and mitigation requirements.

What is remains unknown is the potential impacts to the fishery support functions of the Skookumchuck River from the change in operation of the Skookumchuck Dam. No conclusions can be made regarding potential cumulative impacts to fish as this time, but this resource would be the subject of further evaluation during the design phase of the preferred alternative.

5.2.1.7 Land Use and Planning

Several design features of the preferred alternative are intended to minimize the impacts on land uses. The levees and floodwalls would be set back away from the Chehalis River and its tributaries to the greatest extent practicable, while offering protection to significant tracts of developed land. Existing roads, levees, and other structures would be incorporated into the design wherever possible to reduce impacts to these existing features. Additionally, floodwalls would be used in certain areas to minimize the footprint of the structure and to avoid impacts on existing buildings and infrastructure.

Under the current design, large areas of undeveloped land within the floodplain would not be protected from flooding. These unprotected areas would not be expected to undergo urban-type development. Undeveloped lands that would be protected as a result of the preferred alternative would undergo urban development in accordance with the local jurisdictions' comprehensive plans. These comprehensive plans would be periodically reviewed and amended in accordance with the Growth Management Act.

The preferred alternative also incorporates modifications to the Skookumchuck Dam to aid in the reduction of peak flows during flood events. These modifications would provide additional flood control storage that would significantly reduce peak flood stages in communities downstream, thereby reducing flood damage to structures located in the floodplain. However, areas within the floodplain that are protected would only undergo development under the purview of comprehensive plans adopted under the Growth Management Act.

The dominant land uses in the study area are expected to remain agricultural and residential with a gradual increase in commercial and industrial land uses as the population in the area increases, which is consistent with expectations of existing conditions. The design considerations incorporated into the preferred alternative would minimize the potential for impact to surrounding land uses. No information is available on the extent of potential future actions, but these actions would be subject to current and future land use requirements. No significant cumulative impacts are expected.

5.2.1.8 Recreation, Public Access, and Visual Resources

Cumulative impacts for recreation would involve dispersal of recreation activities to other areas, as opportunities under the preferred alternative would become limited during construction.

However, recreational opportunities could return to areas immediately impacted as construction progressed to other areas within the study area. The preferred alternative will result in no changes to existing conditions. No information is available on the extent of potential future actions, but these actions would be subject to avoidance, minimization, and mitigation requirements. No significant cumulative impacts to recreation, public access and visual resources are expected to result from the preferred alternative.

5.2.1.9 Transportation and Traffic

The preferred alternative would result in the permanent modification of some roadways, including raising a portion of SR6 and raising or relocating portions of arterial and secondary routes on top of the levees. However, the modifications would have a beneficial effect on transportation systems, since the preferred alternative would provide flood protection for the portion of I-5 that is currently subject to flooding, as well as protection for local roadways, the airport, and rail lines. This is a change from past conditions, but is consider a beneficial change.

No information is available on the extent of potential future actions, but these actions would be subject to transportation and traffic analysis. No significant cumulative impacts to transportation and traffic are expected to result from the preferred alternative.

Although there would be temporary impacts on transportation during construction, the preferred alternative is designed to avoid unnecessary impacts and minimize unavoidable impacts to existing roadways and rail lines. Overall, the preferred alternative is expected to provide a significant benefit to transportation systems in the area. It would reduce flooding of local roadways, rail lines, and airport facilities, and provide the flood clearance that is needed in order to implement improvements to I-5 in the Centralia-Chehalis area. No significant cumulative adverse impacts to transportation are expected as a result of the preferred alternative.

5.2.1.10 Air Quality

The preferred alternative consists of passive flood control features. These features are not anticipated to generate air pollutants. There would be no change to existing conditions. No information is available on the extent of potential future actions, but these actions would be subject to avoidance, minimization, and mitigation requirements. No cumulative effects to air quality in the study area are expected.

5.2.1.11 Noise

Noise associated with the construction of the preferred alternative is temporary and does not contribute to cumulative effects to the study area. Long-term noise created by the operation and maintenance would be limited to periodic mowing. These structural features of the preferred alternative would not generate operational noise. No change to existing conditions is expected.

No information is available on the extent of potential future actions, but these actions would be subject to avoidance, minimization, and mitigation requirements. No significant cumulative effects to the study area are expected.

5.2.1.12 Hazards and Hazardous Materials

Accidental spills of construction materials harmful to the environment, such as concrete, sealants, oil and other fuels, during construction of the preferred alternative could contribute to cumulative impacts on water quality. Although they would be infrequent and not intentional, accidental spills could occur during construction near stream channels or on the banks of stream channels.

The cumulative impacts of toxic contaminants would be less than significant because toxic material control and spill-response plans would be implemented for major construction projects in the watershed to avoid or control potential accidents. Hazardous waste mitigation measures would ensure that construction activities associated with the proposed action would not contribute to effects from hazardous materials on people or the environment. No changes to existing conditions are expected. No information is available on the extent of potential future actions, but these actions would be subjected to the rigorous generation and handling controls if hazardous substances are associated with any proposed project.

The preferred alternative would not directly contribute to cumulative effects involving hazardous materials because this alternative would not include the long-term use, generation, storage, or disposal of hazardous materials. No significant cumulative effects to the study area are expected.

5.2.1.13 Cumulative Impacts on Cultural Resources

The preferred alternative has the potential to adversely affect historic properties or culturally important resources if they are present within the area proposed for project implementation.

Historic properties are a finite resource; only some have survived the damages caused by time, natural degradation, and continuing land uses. The goal of Federal resource protection is to preserve the best available examples of resource types. The preferred alternative is likely to affect prehistoric archeological sites, traditional cultural properties, or early settlement or industrial sites. There is potential to affect locations of cultural importance to Tribes that are not encompassed by Federal historic preservation law. The degree to which cultural resources would be affected is based on the actual footprint of the preferred alternative. The alignment of the preferred alternative is confined to the boundaries of urban development and set back from the river and major features of the floodplain (oxbow lakes and meanders). This may reduce the extent of the potential impacts.

The major factor of right of entry makes assessing the cumulative impact of the preferred alternative on cultural resources quite difficult and subjective. The data on cultural resources is uneven due mainly to the right of entry problems encountered during review of the known sites.

Without testing, the actual subsurface character of most of the archaeological sites in the study area is unknown. Plus lacking such information that can usually be obtained in settings like this by archaeological testing, the status of most of the sites in terms of eligibility for the National Registry is unknown. Potential cumulative impacts cannot be concluded at this time, but would be the subject of investigations during the design phase.

No information is available on the extent of potential future actions, but these actions would be subject to avoidance, minimization, and mitigation requirements.

5.2.1.14 Irreversible and Irretrievable Commitment or Resources

Construction of the proposed alternative will include many features considered permanent, or modifications to existing features. Project features which may be considered irreversible would be construction of the levee's and the dam modifications. Resources that could be considered irreversible and irre4trievable would be the commitment of resources such as state and federal funding to purchase lands and labor and to operate and maintain the alternative. At this time there are no commitments of resources that are irreversible and irretrievable except for the cost of producing this DEIS.

5 .2.1.15 Relationship Between Short Term Uses and Long Term Productivity

While regional conditions may improve, short-term or localized conditions should improve after the initial impact of construction. Overtime the entire area should improve dramatically for existing wildlife resources. Further studies and monitoring will be critical to the over all recovery and maintenance of habitat for wildlife and fisheries in this area.

5.3 Findings of Significance

No significant cumulative impacts are expected to occur due to the preferred alternative for hydrology and hydraulics, river geomorphology, wildlife, land use and planning, recreation, public access and visual resources, transportation and traffic, air quality, noise, and hazards and hazardous materials. In consideration of past, on going and reasonably foreseeable impacts, the project has the potential to cumulatively impact water quality, fisheries, and wetlands and riparian areas; additional study during design would be focused on potential cumulative impacts associated with the Skookumchuck Dam. Cumulative impacts to cultural resources cannot be concluded without additional study. This would be done during the design of the preferred alternative.

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