This page and related documents are a work in progress. These are not final documents. Written comments made be made on these topics.

-

Back to top or back to home page or back to Whats New

-

1.0 Introduction

Back to top or back to home page or back to Whats New

-

1.1 Project Background

The Seattle District, U.S. Army Corps of Engineers (Corps) and Lewis County (County) have partnered to develop a General Reevaluation Report/ Environmental Impact Statement for a previously authorized flood reduction project in the Chehalis River Basin (CRB). The Corps and County have developed seven major alternatives to reduce flood hazards to the cities of Centralia and Chehalis and the adjacent urban areas.

Ecosystem restoration opportunities will be identified in conjunction with this flood control reevaluation in order to ensure that restoration measures and project alternatives are compatible and provide the most appropriate type and scale of environmental benefits. Fish and wildlife habitat restoration plans will be focused within the study area in the following general locations: flood plain limits along the mainstem Chehalis River roughly between Doty and Grand Mound, along the Skookumchuck River downstream of Skookumchuck Dam, and along the Newaukum River, but may also include tributaries in each of these areas.

The alternatives are still being developed and do not yet specify area that may be impacted or the expected level or extent of impact. Habitat surveys and alternatives modeling are ongoing and those data will aid with final determinations for restoration/ mitigation locations and actions. In this report, we will assess the potential impacts of alternatives at a general level and identify possible restoration/mitigation opportunities that address these types of impacts. Identification of some potential restoration projects and locations was conducted during visits to the CRB in August and September 2000.

Back to top or back to home page or back to Whats New

-

1.2 Overview of Chehalis River Basin

The Chehalis River Basin (CRB) encompasses approximately 2,114 square miles and includes portions of the Western Cascades, Willapa Hills, Black Hills and Olympic Mountains. The Chehalis River and its tributaries flow through seven Washington counties including Cowlitz, Grays Harbor, Lewis, Mason, Pacific, Thurston and Wahkiakum. The basin is predominantly rural, but has centers of population in the twin cities of Centralia and Chehalis in the middle part of the basin and Aberdeen, Hoquiam and Cosmopolis at the mouth of the river near GrayÆs Harbor. Several smaller towns including Napavine, Pe Ell, Doty, Dryad, Adna, Rochester, and Oakville are within the study area. The primary area of concern for flooding problems lies within Lewis, Grays Harbor and Thurston Counties and includes the mainstem Chehalis downstream of the South Fork confluence, and the Skookumchuk and Newaukum Rivers. Some smaller tributaries also cause localized flooding in the study area. The cities of Centralia and Chehalis experience the most significant flooding and Interstate 5 has also been closed at times due to flooding.

Coupled with the serious flooding problems in the basin, the natural ecosystem has been degraded and populations of many species of fish and wildlife are in decline. Anadromous salmon species including spring and fall chinook, coho, and chum salmon and winter and summer steelhead and sea-run cutthroat trout occur in the basin. Runs of all of these species have declined significantly (Hess & Knudsen, 1993) and sea-run cutthroat trout is proposed for listing under the Endangered Species Act (Federal Register, April 5, 1999).

As a result of both of these problems, the Corps and the County are seeking to develop a joint flood hazard reduction plan and habitat restoration plan. This report will primarily address habitat restoration elements of the project.

Back to top or back to home page or back to Whats New

-

1.3 Purpose of Restoration Plan

The goal of this restoration plan is to improve ecosystem functions and processes that maintain and create habitat for fish and wildlife species in the Chehalis River Basin (CRB). Site-specific restoration projects will also restore or create more localized habitat features that are limited in the system. Restoration alternatives will be developed in conjunction with the flood control alternatives for the purpose of minimizing and mitigating adverse impacts associated with the implementation of flood control alternatives as well as to provide appropriate habitat restoration above and beyond mitigation needs. Potential restoration measures include the reconnection of floodplains and wetlands, creation of off-channel and instream habitat, riparian revegetation, fish passage barrier removal, and direct and indirect benefits to water quality.

Back to top or back to home page or back to Whats New

-

2.0 Basin Limiting Factors to Fish and Wildlife Production

Watershed scale processes fundamentally affect the health of fish and wildlife populations within a basin. Six components of watersheds in the Pacific Northwest include the geomorphic setting of the basin, hydrologic patterns, water quailty, riparian and floodplain characteristics and habitat characteristics (Naiman, et al. 1992). Conditions that limit the ability of a large scale process/component to operate, can cause a limiting factor for fish and wildlife survival and production within a watershed, regardless of how well other processes or components may be operating. Unfortunately, many watersheds affected by human development have had several processes disturbed or limited.

The primary literature sources of habitat conditions in the basin, used in this report, were the Limiting Factors Report (Smith & Wenger, in preparation), which compiled data from the Skookumchuck, Upper Chehalis, and South Fork Chehalis Sub-Basins and Hess & KnudsenÆs (1993) summary of fishery resources in the basin. The mainstem Chehalis downstream of the South Fork confluence was not addressed by the limiting factors analysis and data for this area is currently being collected via habitat surveys. The Limiting Factors Report is in draft form and may change before it is officially finalized. Several site visits were conducted to the CRB with Corps, PIE and tribal staff. Visual observations from these visits are also included.

Back to top or back to home page or back to Whats New

-

2.1 Fish Passage Barriers

Fish passage barriers consist of human caused conditions or structures that hinder or prevent fish passage and can include dams, culverts, or other artificially constructed partial or complete structures. These barriers can limit passage for one or more fish life stages such as for adult spawning or migration, and/or juvenile migration and winter rearing/refuge. Barriers reduce fish production because they reduce the overall area available for fish to utilize. Downstream transport of spawning gravel and large woody debris (LWD) are also hindered by barriers. The Skookumchuck Dam is the largest barrier in the CRB. It currently blocks passage to all anadromous fish, although steelhead trout are trucked upstream of the dam and pass downstream via a passage facility. Culverts make up the majority of the remaining barriers. Fish passage barriers could also include velocity impediments or poor water quality such as high temperature or low dissolved oxygen barriers.

Back to top or back to home page or back to Whats New

-

2.2 Floodplain Connectivity

The lack of off-channel and wetland habitats throughout the Chehalis Basin are limiting factors associated with a reduction of floodplain connectivity. The conversion of active channels to inaccessible ponds has occurred in several areas as a result of agricultural ditching and pond construction for settlement of mine tailings. Other conditions that prevent meandering and side-channel development include bank hardening through the use of rip-rap or dikes, channel realignments, and the existence of a high number of roads or levees. Rip-rap and channelization prevent the development of off-channel habitats, which are important rearing and refuge areas for salmonids. Channelization also contributes to increased bed scour, which destroys spawning areas and reduces other habitat features and may further reduce floodplain interactions by channel incision.

Back to top or back to home page or back to Whats New

-

2.3 Streambed/Sediment Conditions

Changes in sediment load and transport within a system can have negative impacts. A lack of cobble/gravel sediment leads to decreased salmon spawning, while an increase in fine sediments can cover over spawning areas and reduce egg survival. Sediment quality is an indicator of erosion and deposition processes in the watershed. The causes of poor sediment conditions in the CRB include the Skookumchuck Dam, a lack of LWD to maintain coarse sediment, bank and surface erosion, channelization of the river, and landslides. Low occurrence of LWD in a stream can lead to greater sediment transport, which removes gravel from spawning habitat, greater channel instability, less pool habitat and cover available for migrating and rearing salmonids, and higher energy flows that can increase scour. Bank erosion is also a source of fine sediments into streams, which can suffocate salmonid eggs and decrease size and availability of interstitial spaces used by small juveniles for rearing. Landslides are also a major problem in the upper portions of the CRB. Although sediment delivery through landslides does not occur at high levels in the CRB, debris torrents and dam-break floods have scoured channels and contributed to a decrease in LWD in the past. Most non-natural surface erosion comes from dirt and gravel roads and forestry/agricultural lands.

Back to top or back to home page or back to Whats New

-

2.4 Riparian Conditions

Poor riparian conditions are caused in the CRB by riparian harvest, dam break floods, fires, agriculture, and development. Areas with no vegetation, little vegetation, or vegetation that is composed primarily of young deciduous trees characterize poor riparian conditions. Areas with little or no vegetation do not provide adequate shade and those areas may experience increased water temperatures, which limit fish survival and reproduction. They also do not provide LWD recruitment, or cover to the streams and do not provide a buffer for stormwater runoff or other human activities. Riparian zones composed of deciduous forest are typically unable to provide adequate LWD recruitment (especially since most of these forests are also young), which leads to increased sediment transport, decreased pool habitat, and increased scour, as described above. Narrow or otherwise poor riparian zones also do not provide adequate cover for wildlife movements along stream corridors.

Back to top or back to home page or back to Whats New

-

2.5 Water Quality

The primary water quality problem in the CRB is high water temperatures, although pH and fecal coliform are also an issue in some areas of the watershed. High water temperatures and their associated impacts are frequently due to loss of tree canopy and lack of groundwater and wetland discharge during low flows. Although enhanced water quality is not usually the primary goal in restoration actions, it may be improved indirectly in areas where poor riparian and floodplain conditions are addressed. Fecal coliform contaminated can be directly addressed by the use of livestock fencing and riparian buffers.

Back to top or back to home page or back to Whats New

-

3.0 Geomorphic Constraints/ Opportunities

The discussion presented in this section is based primarily on field observations during a reconnaissance trip conducted September 7, 2000 through September 9, 2000. This effort provided a good overview of the conditions and various processes occurring within the project area and the basis to develop initial opinions concerning geomorphic constraints and opportunities associated with potential mitigation measures. Additional field work and analysis will need to be conducted to further verify, evaluate and develop the geomorphic basis for identifying, selecting and designing mitigation and restoration measures. A discussion of the information and effort needed to complete the geomorphic assessment is included at the end of this section.

Back to top or back to home page or back to Whats New

-

3. 1 Mainstem Chehalis

The Chehalis River in the primary study area, RM 57 to RM 79, has several geomorphic characteristics of considerable importance in identifying restoration and mitigation measures. The system is relatively low gradient and of low to moderate energy. The low gradient is most pronounced upstream of the Skookumchuck confluence where the gradient is less than 1 foot per mile (Reichmuth, et. al., 1998). In other areas of this reach, the gradient is steeper at 3 feet per mile, but still relatively low. Much of the bed was observed to be comprised of sands and finer materials. Near the lower end of the reach, gravels become evident in the channel with several significant bars observed upstream of the Independence Road bridge near Rochester.

Throughout much of the reach, the channel banks are quite high with erosion observed in some areas. Erosion of many of the higher banks may possibly be a result of geotechnical instabilities created by the high, steep banks rather than hydraulic forces. In such cases, the flow serves to remove material that has failed due to gravitational forces and thus prevents accumulation of material at the toe of the bank that would stabilize the bank. However, the initial bank failure mechanism is gravitational forces. The lack of vegetation and land use practices that do not leave a buffer zone between the channel and agricultural lands are contributing to accelerated bank erosion in areas. Although, there are areas of observed bank erosion, it does not appear that there are areas of significant lateral migration. The channel appears to have not experienced significant changes in alignment for many decades. The issues of lateral migration, changes in channel alignment and changes in channel width over time need to be investigated based on comparison of historic aerial photos and maps from different periods.

Of great importance is the observation that the channel may have incised. This observation is based on the high banks, low width to depth ratio and behavior of several of the major tributaries near the confluence with the Chehalis River. In the latter case, both the Newaukum and Skookumchuck Rivers appear to exhibit steepened profiles just upstream of the confluence with the Chehalis. The extent of channel incision needs to be investigated further through determination of the return period that the channel spills out of the banks and into the floodplain and comparison of indicators of past bed elevations such as specific age analysis at long term gaging stations, historic cross section surveys and historic photographs.

The above geomorphic observations have implications as to potential restoration and mitigation efforts associated with implementation of the flood control project. These are listed below.

Two localized, upstream sites were visited on the Chehalis River, RM 87 and RM 101. The RM 87 site is located just downstream of the confluence of with the South Fork. The RM 101 site is located several miles upstream of Rainbow Falls State Park near Doty. In the RM 87 area, significant bank erosion is occurring and several large gravel bars are present. Toe protection and upper bank shaping combined with revegetation would be beneficial at RM 87. Much of the gravel creating the accentuated point bars in this reach may be locally derived from bank erosion. Thus controlling the bank erosion could greatly reduce the apparent overloading of gravels in this area. At RM 101, the banks appear more stable and soft bedrock outcrops exist along the toe of both banks. Opportunities for enhancement or restoration at the RM 101 site appear to be limited.

Back to top or back to home page or back to Whats New

-

3.2 South Fork Chehalis

Only two localized sites were observed on the South Fork Chehalis, at RM 0.3 and RM 5. The RM 5 site designation is only approximate. The RM 0.3 site is in the area of the Highway 6 crossing. At this location, the channel banks are relatively low and the stream does not appear incised. There is a low-lying floodplain that is several thousand feet wide. At the assumed RM 5 location (a bridge crossing), the South Fork has a much deeper channel than at RM 0.3. The channel has incised to a soft bedrock layer and there are several feet of fall over the exposed outcropping. The riparian corridor is narrow at the RM 5 crossing with only a thin row of trees along the bank. Downstream at the RM 0.3 site, the corridor occupies the low-lying floodplain. At this lower site, there may be opportunities for wetland creation and greater floodplain interaction. At both sites, the potential for LWD to enhance in-stream habitat should be investigated further.

Back to top or back to home page or back to Whats New

-

3.3 Skookumchuck River

The study reach of the Skookumchuck River extends from the confluence with the Chehalis at RM 0 to the Skookumchuck Dam at RM 22. This 22 mile reach covers a wide range of conditions. At the base of the dam, for about 1 mile downstream , the high gradient channel is confined to a narrow canyon. The bed is comprised of gravel, cobble and boulders with some bedrock outcrops. The Skookumchuck then meanders through a mile wide valley until about RM 12. The bed material through this reach is primarily gravel with some cobbles. The gradient is moderately steep and riffle /pool sequences exist, although there are stretches observed with long rather uniform riffles or steep runs. At RM 12, the channel takes an abrupt 90 degree turn and follows another valley that is only about 1,000 to 2,000 feet wide. The channel follows this valley through Bucoda. Within this reach, the channel is lower sinuosity and has some very straight reaches which may indicate past channelization activities. The bed material is predominately sand or fine gravels. The gradient has decreased noticeably in this reach. There are areas where large cobbles are scattered on the bed. Considering the hydraulics and the appearance of the cobbles as scattered material rather than as a bar or integrated matrix of graded material, this large material is likely remnants of material that was left by paleo channels or eroded from the material in which the channel is formed. At RM 5, the channel abruptly leaves the confinement of the valley and flows across an alluvial fan to the confluence with the Chehalis River (Reichmuth, et al, 1998). The gradient of the Skookumchuck becomes much steeper for several 100 feet upstream of the Chehalis confluence. As previously mentioned, this may be evidence of channel incision on the Chehalis.

Areas of bank erosion were noted throughout the 22 mile reach, although, like the main stem of the Chehalis, it appears that the rates of lateral migration are low and the channel has remained in its current alignment for decades. As is typical of most of the other streams in the study area, the riparian vegetation has been limited to a narrow strip (one tree wide) adjacent to the banks. In some areas, pastures or fields extend to the top of the stream bank without woody vegetation separating these agricultural lands from the stream banks. The exception to this is the one-mile reach below the dam (game management area) that has woody vegetation across most of the valley floor.

Opportunities for mitigation and restoration measures exist throughout the Skookumchuck study reach. These opportunities vary dependent on the stream characteristics. A summary of the most significant opportunities is listed below.

Back to top or back to home page or back to Whats New

-

3.4 Newaukum River

A reconnaissance of the Newaukum River was conducted from the confluence with the Chehalis to the Interstate 5 crossing near RM 7.3. Bank erosion was noted at several locations in this reach and soft bedrock or clay pan was exposed at Rush Road bridge crossing. In the area of the Chehalis railroad bridge and Devereese Road bridge, it appears that some realignment of the channel has taken place as part of bridge construction activities. Throughout the reach the banks are moderately high and the width to depth ratio relatively low. The banks appear to get higher in the downstream direction. These observations indicate the possibility that the Newaukum has experienced incision similar to the Chehalis. Opportunities for enhancement and restoration on the Newaukum are similar to those on the lower reaches of the Skookumchuck.

Back to top or back to home page or back to Whats New

-

3.5 Smaller Tributaries

Observations on the smaller tributaries, Salzer Creek, Bunker Creek and Elk Creek are limited. The evaluation areas assigned were specific RM locations or reaches of 0.5 miles in length or less. At each of these sites there were opportunities to increase flood plain storage increasing restriction by existing road crossings or increasing the flow resistance in the flood plain. Because these sites control a very small portion of the Chehalis watershed, even with significant reductions in peak flows from the individual streams, the impact on the flood peaks in the Chehalis River may be minimal. This is an issue that needs to be addressed by the UNET model developed by PIE. It may take many similar projects to have a noticeable influence on discharges in the mainstem Chehalis. However, these types of efforts might be considered as part of a long-term watershed flood reduction program. These initial sites could also be part of a demonstration project to verify flood storage benefits and assess habitat benefits from floodplain connectivity.

At each of the sites, the potential for downstream impacts due to reduction in sediment loads would need to be investigated. Ponding of water above the flow restrictions would reduce the sediment load downstream and the possibility for channel degradation would exist. The most significant potential exists at the Salzer Creek RM 2.75 site since this is where the finest bed material was observed.

Salzer Creek Both locations visited, RM 2.75 and RM 4.0 were culvert crossings. At the RM 2.75 crossing, only a very small channel on the order of a foot or two deep and several feet wide was defined. At any appreciable discharge, the flow will spread out across the relatively flat valley floor. There appears to be a high potential for enhancement and establishment of wetlands at this location that would also assist in increasing floodplain storage and retarding of peak flows.

Elk Creek In the area of RM 2.8, Elk Creek is confined in a canyon, although the degree of confinement is less than the reach immediately downstream. The downstream reach flows through a very narrow canyon for over a mile. The potential for channel bed degradation below this site does not exist, since the profile is controlled by large cobbles, boulders and bedrock through the canyon. Flow restrictions at this location would need provisions for fish passage since the stream is large enough to still provide moderate quality habitat.

Bunker Creek Only the RM 2.5 site was visited. This site consists of a culvert crossing. The channel has significant overhanging vegetation both upstream and downstream of the culvert, nearly obscuring the view of the channel. Bank erosion is occurring downstream of the culvert as the concentrated flows impinge on the outside of a sharp bend immediately downstream.

Back to top or back to home page or back to Whats New

-

3.6 Data and Analysis Needs to Complete Geomorphic Analysis

Additional field reconnaissance, data collection and analysis need to be performed to verify existing geomorphic observations and to provide a thorough understanding of conditions in the study area.

Obtain and analyze cross section locations and cross section data from the 240 cross sections from the hydraulic model study (PIE)

Determine channel geometry parameters such as top width, depth, and width to depth ratios

Develop longitudinal profiles of the main stem and tributaries

Determine bank heights

Obtain hydrology at various locations on main stem and tributaries in the study area 1.5-, 2- up to 100- year for existing and with project conditions

Perform continuous reconnaissance of the reaches (boat or foot and possibly aerial) of main stem and tributaries

ID geologic controls

Sample bed material

Identify erosion sites

Characterize bank material and bank vegetation

Determine representative reaches to obtain more detailed field information

Obtain and review results of UNET in terms of hydraulic conditions for a range of flows including:

Bankfull discharge at various locations

Channel velocities

Distribution of flow between the floodplain and main channel

Channel depths

Shear stress

Survey limited cross sections in representative reaches of each reach within a study area if existing cross sections are not adequate to determine geomorphic characteristics

Perform incipient motion analysis to determine the sizes of bed material in transport at various flow levels

Perform historic aerial photo analysis to determine changes in channel alignment, channel width and to define existing plan from parameters

Obtain and review soils and geologic maps

Obtain available information from working group on mitigation ideas

Obtain available information from working group on geomorphology and sediment transport

Back to top or back to home page or back to Whats New

-

4.0 WATERSHED Restoration Needs and Opportunities

The alternatives currently proposed will impact the CRB in a number of ways. Any flood control measures could result in any combination of the following impacts; 1) changes in riparian and floodplain habitat, 2) an increase in erosion and turbidity, 3) decrease in LWD recruitment, 4) reduced access to or existence of off-channel habitat, 5) substrate modifications, and 6) recharge of wetlands or floodplain areas. In an attempt to address these impacts through restoration and/or mitigation, the following list of potential restoration actions have been identified.

Back to top or back to home page or back to Whats New

-

4.1 Channel Diversity (Off-Channel and Instream Habitat)

Off-channel habitat provides overwinter rearing and refuge habitat for juvenile salmonids. These habitats, and their associated riparian zones, are also valuable for many species of waterfowl, migratory birds and mammals. More natural river meanders, increased sinuosity, and natural creation of off-channel habitat could be possible if bank hardening structures were removed (rip-rap) and connections made to existing isolated off-channel habitats. Placement of large woody debris would introduce in-stream cover and in-channel structure, increase channel complexity, and increase sediment storage, particularly spawning gravel retention.

Back to top or back to home page or back to Whats New


4.2 Riparian Zone

Revegetation of riparian areas that have been cleared would increase shading and potentially lower temperatures that do not currently meet Class A standards, particularly in the tributary streams. Riparian zones also provide cover, and nutrient and detrital input into the aquatic ecosystem. Underplanting of riparian areas that are dominated by deciduous forest with more conifer species would increase LWD recruitment. Riparian revegetation would also result in reduced surface and bank erosion and improved filtration of runoff from the floodplain and uplands. Riparian zones are important corridors for wildlife movements and are also extensively utilized by many species as primary foraging and nesting sites.

Back to top or back to home page or back to Whats New


4.3 Floodplains and Wetlands

Setting levees back or removing unnecessary or non-functioning levees would reconnect the stream to its floodplain in specific locations. Currently, the mainstem Chehalis River is highly incised and channelized and does not flood over its banks except in infrequent events, greatly diminishing groundwater recharge in the floodplain. Sloping back non-leveed banks and creating excavated floodplains or wetlands would allow more frequent inundation of the floodplain in selected locations and also improve bank stability. Floodplains provide habitat for a variety of fish and wildlife species and are especially effective at reducing water velocities, trapping sediment, and providing winter rearing habitat for juvenile salmon. Road re-routing would also be conducive to increased floodplain connectivity. Revegetation of floodplain areas would further improve the sediment trapping and groundwater recharge functions. Wetlands can be restored or created in floodplain areas to further allow groundwater recharge and provide seasonal fish habitat during high flows.

Back to top or back to home page or back to Whats New


4.4 Fish Passage

Removal or upgrade of culverts would allow fish passage for all species during all flow conditions. This would result in access to many miles of tributaries that may be inaccessible due to culverts, generally improving production of fish by increasing total area available for spawning, rearing or refuge. Improving culvert passages will also reduce localized flooding associated with insufficiently sized culverts during high flows.

Back to top or back to home page or back to Whats New


5.0 Sub-Basin restoration Needs and opportunities

A comprehensive and thorough evaluation of the existing conditions in the CRB is unavailable. The Limiting Factors Analysis addresses conditions within the Skookumchuck, South Fork Chehalis, and Upper Chehalis Sub-Basins. While portions of these sub-basins are included within the action area for restoration/mitigation actions, the remaining sub-basins have not been evaluated for limiting factors. Recommendations for restoration actions have been limited in this report to the areas specified within the scope of work, including the flood plain limits along the Chehalis River, along the Skookumchuck River downstream from Skookumchuck Dam, and along the Newaukum River. In addition, there are at least 4 tributaries that would be appropriate restoration locations, including China Creek, Salzer Creek, Hanaford Creek, and Elk Creek, all mainstem Chehalis tributaries.

Back to top or back to home page or back to Whats New


5.1 Mainstem Chehalis River

Erosion noted in LFA for the Upper Chehalis Basin mainstem, no locations given

Erosion observed during field visits along mainstem, adjacent to agriculture and development, downstream of the South Fork confluence

Low numbers of LWD throughout the mainstem, especially key pieces >12ö diameter

Poor riparian zone observed on mainstem above and below South Fork confluence (typically one tree wide). Riparian revegetation is an important need.

High water temps noted on mainstem in numerous locations in 303(d) listing; also listed for fecal coliform and PCBs. Livestock fencing and groundwater recharge could reduce these problems.

Off-channel habitat near SR-6 can be created through oxbow reconnection to mainstem

Off-channel habitat can be created through reconnection to existing oxbows near Salzer Creek mouth, and along Scheuber Ditch.

Back to top or back to home page or back to Whats New


5.2 South Fork Chehalis River

Culverts of unknown fish use and passability (64)

Numerous sites of rip-rap bank hardening

In-channel LWD reported ôbelow targetö in 140 of 143 sites sampled for LFA

Loss of riparian vegetation throughout the lower and middle reaches of the mainstem South Fork

High water temperatures on South Fork mainstem, one 303(d) listing for high temperatures. Riparian revegetation can help reduce this problem.

Back to top or back to home page or back to Whats New


5.3 Skookumchuck Sub-Basin

Culverts of unknown fish use and passability on several Skookumchuck tributaries (9)

Bank hardening in the form of rip-rap primarily between RM 3-6

Bank erosion was noted in 180 locations by Wampler et al. (1993)

Fine sediments high downstream of the dam

Riparian vegetation loss, no specific locations given in LFA, but observed during field reconnaissance to be prevalent along most of the river. Riparian revegetation is an important need.

303(d) listings for fecal coliform, pH and high temperatures. Livestock fencing and riparian revegetation can reduce these problems.

Back to top or back to home page or back to Whats New


5.4 Newaukum River

Riparian vegetation loss prevalent

303(d) listing for fecal coliform and high temperatures. Livestock fencing and riparian revegetation can reduce these problems.

Back to top or back to home page or back to Whats New


5.5 Smaller Tributaries

Back to top or back to home page or back to Whats New


5.5.1 China Creek

Culverts of unknown fish use or passability (13)

Contained in long culverts and rock and concrete lined channels between RM 0-2

Back to top or back to home page or back to Whats New


5.5.2 Salzer Creek

Riparian vegetation loss prevalent

303(d) listing for fecal coliform and high temperatures. Livestock fencing and riparian revegetation can reduce these problems.

Back to top or back to home page or back to Whats New


5.5.3 Hanaford Creek

Culverts of unknown fish use or passability (5)

Conversion of active channel to inaccessible ponds on 8.25 miles of lower Hanaford watershed

Rip-rap hardening in many unspecified locations

Riparian vegetation loss in most of watershed. Riparian revegetation is an important need.

Back to top or back to home page or back to Whats New


5.5.4 Elk Creek

Culverts of unknown fish use or passability (3)

Several unspecified cases of rip-rap hardening noted

High road densities (4.4 miles of road/ square mile) leading to high erosion and sedimentation

Limited LWD presence and potential for recruitment

Riparian vegetation loss, most pronounced from RM 0-3

High water temperatures from RM 0-3

303(d) listing for fecal coliform

Livestock fencing and riparian revegetation can reduce water quality problems.

Back to top or back to home page or back to Whats New


6.0 SUMMARY OF RECOMMENDED LOCATIONS, ACTIONS, AND FURTHER INVESTIGATION

Back to top or back to home page or back to Whats New


6.1 Table of Potential Restoration Actions

Location Action Description
SR 6 Oxbow Reconnection Three potential oxbows to reconnect and provide riparian revegetation
Scheuber Ditch Side Channel Connection/Creation Could connect Scheuber Ditch up to oxbow near SR 6 and improve downstream connection to Chehalis River, riparian revegetation
Centralia Reach Oxbows Oxbow Reconnection Several additional oxbows could be reconnected to Chehalis River, riparian revegetation
Salzer Creek Mouth Floodplain/Wetland Restoration An existing oxbow near the mouth of Salzer Creek could be reconnected, with additional excavation to reconnect some floodplain area and create a seasonally inundated wetland, wetland and riparian revegetation
Salzer Creek above I-5 Floodplain/Wetland Restoration Salzer Creek could be reconnected to site currently used for food processing waste; wetland and floodplain habitats could be reconstructed, riparian revegetation
Salzer Creek Floodplain Storage Areas Floodplain/Wetland Restoration In locations where a restricting structure may be placed to provide flood storage during high flows, the floodplain could be restored with a diversity of wetland, upland and riparian habitats.
Skookumchuck River Oxbow/Pond Reconnections Some old oxbows or isolated ponds exist near the Skookumchuck River near Centralia which could be reconnected, riparian revegetation
Tributaries Riparian Revegetation, LWD Placement Nearly the entire watershed would benefit from riparian revegetation. Locations along the Skookumchuck River, Newaukum River, Hanaford Creek, Salzer Creek and other tributaries could be selected.
Various Mainstem Chehalis Locations Riparian Revegetation Areas of high bank erosion due to loss of vegetation could be identified and revegetated.
Various Mainstem Chehalis Tributaries Fish Passage Barrier Removal/Replacement Replace culverts or other barriers that prevent fish passage to good quality upstream habitats.

Back to top or back to home page or back to Whats New


7.0 Evaluation of impacts of flood control alternatives and Benefits from Restoration projects

Back to top or back to home page or back to Whats New


7.1 Methodology

The attached evaluation framework (Appendix 1) is based upon the Skagit Watershed Council Report on Watershed Processes and the evaluation frameworks developed and applied by the Corps of Engineers, Snohomish County, and King County (with involvement by an interagency steering committee) for the Stillaguamish River Restoration Study and the Green-Duwamish River Basin Restoration Study. All of these studies focused on restoration of ecosystem-level functions and processes as well as specific habitats for threatened and endangered salmonids. The draft framework is designed to provide a numerical estimate of both the environmental impacts from the flood control alternatives as well as the benefits provided by alternative restoration plans and will provide information needed to assess mitigation needs and scale. The framework is intended to differentiate across alternatives and will provide information required for the cost effectiveness and incremental cost analysis. The evaluation form will be completed for each flood control alternative and each restoration plan or specific project. Please note that the third question is an attempt to address species of concern and the species list used may need to be expanded, depending on potential future issues.

Back to top or back to home page or back to Whats New


7.2 Flood Control Alternatives

-- To be evaluated.

Back to top or back to home page or back to Whats New


7.3 Restoration Projects

-- To be evaluated after projects

and plans have been developed.

Back to top or back to home page or back to Whats New


7.4 Restoration Plans for Each Alternative

-- To be developed.

Back to top or back to home page or back to Whats New


8.0 Conclusions and recommendations

The Limiting Factors Analysis (Smith & Wenger, in prep.) is currently a draft report that only covers the Upper Chehalis mainstem, South Fork Chehalis and Skookumchuck River. Data from on-going habitat surveys will be needed to further clarify restoration needs and potential restoration locations, particularly in the Centralia Reach and the Newaukum River.

From visual observations made in the CRB during August and September, the key restoration opportunities appear to be: 1) reconnection/creation of off-channel habitats along the mainstem Chehalis; and 2) riparian and floodplain restoration on the tributaries to the Chehalis, including the Skookumchuck and Newaukum Rivers and Salzer, Hanaford and other Creeks. The reconnection or creation of off-channel habitats along the mainstem Chehalis would provide critical rearing and refuge habitats for juvenile salmon during winter and spring flows and also provide an opportunity for floodplain groundwater recharge and reduced velocities and scour in the mainstem. Riparian and floodplain restoration along the tributaries will have a more significant shading and water temperature reduction effect because of their smaller size. Additionally, restoration efforts on the Skookumchuck and Newaukum Rivers will enhance existing moderate quality habitat and corridors. If the tributary streams can be restored to have relatively high water quality and quantity during low flows, the effect on the mainstem could be significant.

Further field surveys at each site will be conducted to verify the existing constraints and potential for restoration. It will be of paramount importance to evaluate how watershed-level processes will be affected by and, in turn, affect any site-specific restoration projects. Actions such as riparian revegetation, which are needed throughout the watershed, should be targeted to locations where the effect will be the most significant (i.e. in the tributaries where shading, water quality buffering and LWD recruitment would have a greater effect).

Back to top or back to home page or back to Whats New


9.0 references

Hiss, J.M. & E.E. Knudsen. 1993. Chehalis River Basin Fishery Resources: Status, Trends, and Restoration. U.S. Fish & Wildlife Service, Western Washington Fishery Resource Office, Olympia, WA.

Naiman, R.J., T.J. Beechie, L.E. Benda, D.R. Berg, P.A. Bisson, L.H. MacDonald, M.D. OÆConnor, P.L. Olson & E.A. Steel. 1992. Fundamental elements of ecologically healthy watersheds in the Pacific northwest coastal ecoregion. in Naiman (editor), Watershed Management. 1992. Springer-Verlag. pp 127-188.

Smith, C.J. & J.Wenger. In preparation. Salmon and steelhead habitat limiting factors in the Chehalis and nearby basins (WRIAs 22 and 23). Washington State Conservation Commission, Lacey, Washington. can be viewed at Website: http://members.home.com/ bioforsalmon/home.htm

U.S. Army Corps of Engineers, Seattle District. 1982. Centralia, Washington Flood Damage Reduction Study, Interim Feasibility Report and Environmental Impact Statement. Seattle, WA.

Wampler, P.L., E.E. Knudsen, M. Hudson, & T.A. Young. 1993. Chehalis River basin fishery resources: salmon and steelhead habitat degradations. U.S. Fish and Wildlife Service, Lacey, Washington.

Washington Department of Ecology. 1994. Upper Chehalis River Basin, Evaluation of Total Maximum Daily Loads Summary Report. Publication #: 94-144. Olympia, WA.

Final Section 303(d) List, 2000. "http://www.ecy.wa.gov/programs/wq/303d/index.html"

Water Quality Assessment. 2000. Website: "http://www.crcwater.org/wqassesm.html"

Back to top
Back to Whats New Index Page
Back to CRC Index Page
Back to Watershed Index Page
Back to Lewis County Issues Index Page
Back to Grays Harbor County Issues Index Page
Back to Thurston County Issues Index Page

This page created and maintained by Chehalis River Council
Send comments or questions to the: Chehalis River Council

Now, you can Search this Chehalis River Council site!