City of Castle Rock Cowlitz River Boat Launch Impact Site and

City of Castle Rock Boat Launch Mitigation Plan Page 1

City of Castle Rock Cowlitz River Boat Launch Impact Site and Mitigation Site Considerations Impact Site The City of Castle Rock proposes to install a rock groin in the Cowlitz River upstream of the boat launch. The purpose of the groin is to improve boat launch safety by redirecting flow and therefore reducing velocities at the site. The proposed rock groin would actually serve to increase habitat diversity within this reach of the Cowlitz River. Similar benefits should result as have been realized at the groins installed along Larson Lane just south of Castle Rock. These groins have become a popular fishing location in that they have created a scour slot and provide slack water utilized by migrating adults. The structure also provides slack channel margin habitat and structure that is utilized as rearing habitat for juvenile salmonids. Mitigation Site To satiate mitigation requirements for the “impact” to the Cowlitz River, the City of Castle Rock proposes to continue stream restoration work in Whittle Creek. This project area offers a robust and meaningful opportunity for salmon recovery due to a collaborative effort between the City of Castle Rock, the Castle Rock High School, and the Cowlitz Conservation District. This collaborative effort was initiated in 1999 and characterized the watershed, assessed resource conditions, and identified restoration opportunities. Subsequently, several restoration and mitigation projects have been implemented in the watershed that addresses restoration opportunities and resource concerns. To offset proposed impacts at the City of Castle Rock boat launch, mitigation opportunities have been identified in the reach of Whittle Creek from the Mouth upstream to the PH10 crossing. Whittle Creek Watershed Background The Whittle Creek watershed encompasses 2,600 acres that supports about 5.5 miles of fish bearing water. According to Washington Department of Fish and Wildlife’s (WDFW) Salmon scape, Coho utilize about 5 miles and Winter Steelhead utilize about 4.5 miles of this habitat. Technicians conducting the habitat surveys on Whittle Creek noted Coho fry in the left bank tributary at the upper extent of the fish utilization. WDFW’s Ecosystem Diagnostic and Treatment (EDT) analysis rating of this watershed indicates that the lower reach from the Cowlitz River to Quick Road (beaver ponds) is high priority restoration opportunity for Winter Steelhead. Anecdotal information collected during watershed assessment efforts indicate that Winter Steelhead and Coho regularly spawn in the stream adjacent to the feed store (between PH10 and Westside Highway). Spring Chinook were common in the lower reaches of the creek prior to the eruption of Mount Saint Helens. High school students that assisted with watershed assessments indicated that they regularly catch cutthroat in the culvert outlet pools at Westside Highway, Umiker and Quick roads. Whittle Creek serves as off channel refuge during high flows in the Cowlitz River. Land use has remained rather consistent within the watershed based on review of aerial photographs back to 1956. The upper third of fish bearing water is forested. The middle third is predominantly agricultural; however, the lower reaches in this section have consistently been associated with beaver ponds. The lower third has been predominantly agricultural. Riparian vegetation located in agricultural use areas has typically consisted of a single row of hardwoods along the creek. The area between Westside Highway and the mouth has been slowly converting to urban growth area since the mid 1960’s.


Prior to the eruption of Mount Saint Helen’s, the mouth of Whittle Creek was wetland habitat with multiple forks and two large open water areas (refer to following image – 1974 aerial photograph). The open water areas may have been a result of gravel mining. The St. Helen’s mudflow impacted the lower 4,000 feet of Whittle Creek by filling the wetland ponds and the channel. The Army Corps of Engineers and Soil Conservation Service collaborated to restore drainage in Cowlitz River tributary streams, resulting the in the trapezoidal channel present today. The area around the constructed channel was utilized for deposition of dredge spoils from the Cowlitz River further impacting the creek by raising banks and limiting establishment of riparian vegetation. 1974 Aerial Photograph of Whittle Creek


Assessments of the Creek included habitat stream surveys and stream temperature monitoring. The primary area of concern for stream restoration is referred to as Lower Whittle Creek. Referring to the following 2009 aerial photograph, Lower Whittle Creek is the reach from PH10 (major east-west oriented road) downstream to the confluence with the Cowlitz River.

From the mouth of Whittle Creek to the PH10 crossing habitat diversity is essentially non-existent. This reach of creek was excavated to a design trapezoidal cross section on uniform grade. The result is a


reach dominated by riffles and shallow glides. The channel is highly confined with little opportunity for sinuosity to develop. From the mouth to PH10 the substrate ranges from predominantly sand to hard-packed sand more characteristic of hard pack mudflow. The creek flows subsurface by late spring with water standing in the glide features. Coho and steelhead juveniles were observed stranded in these glides downstream of PH10. Woody debris does not exist within this reach of Whittle Creek. The following photograph provides a typical cross section view in this reach.

A portion of the stream, from PH10 upstream to Westside Highway serves as an example (reference reach) of potential restoration. Within this section of Whittle Creek, Red Alder had partially, naturally, established following the Mt. St. Helen’s channel reclamation. Floodplains and channel sinuosity has naturally begun to develop. The following photograph illustrates this situation and provides an example of the proposed mitigation in the remainder of Lower Whittle Creek.


Recording thermographs were installed at 5 locations within Whittle Creek including: Site 1, located near the Whittle Creek’s mouth Site 2, located just downstream of Westside Highway Site 3, located just upstream of Umiker Road Site 4, located upstream of Quick Road Site 5, located just inside forest land use Temperature results are presented in a downstream progression. Stream temperature at Site 5 never exceeded the state standard of 64.4 degrees Fahrenheit during summer months. At Site 4 stream temperature consistently exceeded the state standard during summer months. This site was located immediately downstream of the Beaver dam complex above Quick Road. Stream temperature at this location reflected the heat sink afforded by the ponded water. At Site 3 (Umiker Road) stream temperatures returned to near forest land use condition averaging about 6 degrees cooler than stream temperatures above Quick Road. The reduction in stream temperature appeared to be associated with groundwater influx within this reach. Stream temperature exceeded state standards on a daily basis at Sites 2 (Westside highway) and 1 (mouth of Whittle Creek). By the first of August, stream discharge at Site 1 would decrease to a level that would expose the thermograph. Discharge at the other stations was sufficient to allow summer long data collection indicating that stream flow was travelling subsurface in the lower reach. Resource Concerns Summary Coho and Winter Steelhead utilize about 5 miles of habitat within the Whittle Creek watershed. WDFW EDT modeling indicated the reach from the mouth to Quick Road is a high priority for Winter Steelhead habitat. The eruption of Mount Saint Helens and subsequent channel reclamation to remove mudflow deposits grossly transformed habitat in the reach from the mouth to Westside Highway. The reach between Westside Highway and PH10 (behind feed store) naturally seeded with Red Alder and is currently used as spawning habitat by Winter Steelhead. Downstream of PH10 the habitat is predominantly riffle and shallow glides. This impairs juvenile out migration. Summer stream flow goes subsurface throughout this reach further exacerbating out migration resulting in mortality of juveniles due to predation and water quality (high temperature and low/no dissolved oxygen). The lack of pool habitat features limits the ability of Lower Whittle Creek to hold juveniles. Deposition of dredge spoil material along Whittle Creek has resulted in droughty, infertile soils, which are inhospitable to most native vegetation. Existing Restoration Activities Stream restoration activities that have been implemented in the Lower Whittle Creek are presented from upstream to downstream. Cowlitz County implemented a mitigation project just downstream of Westside Highway that created floodplain features and successfully established woody vegetation. The following photograph illustrates the ability to create effective floodplain features but also illustrates the need for a more collaborative approach to restoration efforts. Note the downstream terminus of the project area.


The City of Castle Rock implemented a mitigation project for the boat launch construction project on the reach of Whittle Creek immediately below the Cowlitz County mitigation site downstream to the PH10 crossing. This project consisted of placing a few (3-4) wood structures, managing canary grass, and establishing woody vegetation on the right bank. In areas of hydraulic complexity, pool features are forming and gravel accumulation/sorting is beginning to occur. Mitigation projects constructed by the City of Castle Rock and Cowlitz County would have been most effective if there was greater coordination between the entities and the projects, providing a smooth transition in recovery efforts. The following photograph provides a view of the Large Woody Debris (LWD) placement and bank shaping mitigation project implemented by the City of Castle Rock.


The City of Castle Rock implemented a bank stabilization / riparian restoration project on the lower 200 feet of Whittle Creek. As can be seen in the following photograph, riparian function has been successfully jump started within this project area. Root strength has been restored to the stream bank. Canopy closure is providing shade and food inputs. Terrestrial wildlife is beginning to utilize the riparian corridor. Along the Cowlitz River a mix of Red Alder, Black Cottonwood, and willow has successfully established and can provide a source of native vegetation for future recovery projects.


Stream Restoration Alternatives / Mitigation Opportunities The City of Castle Rock proposes to continue restoration work on Whittle Creek as mitigation for the planned impacts at the boat launch on the Cowlitz River. A sound understanding of the Creek, a collaborative approach toward project development, and the opportunity to compliment other restoration efforts makes the proposed action robust and meaningful. The opportunities presented in this document provide a planned strategy to address resource concerns within the Lower Whittle Creek. This strategy will encompass multiple restoration projects in order to be fully realized. The simple concept is to restore floodplains within the channel cross section and restore riparian function. Placement of wood structures is further recommended to increase hydraulic complexity as site conditions warrant. The intent is encouraging hydraulic complexity within the active channel resulting in scour and deposition. This will begin restoring the pool/riffle sequence missing in the reach and in-time limit subsurface flow. Scour pools will connect with subsurface water at the site providing cold oxygenated water for refuge as summer flow regime approaches. The wood structures will provide hiding cover that will help juveniles evade predation. This should greatly improve survival of juveniles by providing additional time for escapement during late spring freshets. Wood structures would be placed at an approximate spacing of 3-5 channel widths. Riparian restoration will accompany installation of wood structures. During wood structure construction, canary reed grass will be managed in a variety of ways dependent on the restoration area and will range from scarification with equipment during the restoration project to mechanical labor, which requires cutting the grass. Site preparation will focus on


the active floodplain and up the side slope until soil conditions are reached that will not support Red Alder. Exposed soils resulting from restoration work will be seeded with an erosion control seed mix consisting of annual ryegrass and subterranean white clover at a rate of 25 pounds/acre. The seed mix is intended to only provide vegetative cover through winter storm flows. The use of potted plants will allow for planting of Red Alder immediately following restoration practices. Trees will be planted at a density of 680 trees per acre (approximate 8 foot spacing). This effort is focused on restoring the shade, root strength, and energy dissipation values of riparian function. As the Red Alder becomes established, the floodplain roughness will increase. This will serve to reduce energy and velocity of floodplain flow. This will increase velocity with the active channel furthering the effort to increase hydraulic complexity. Lower Whittle Creek has been delineated into 4 primary treatment areas. These are shown on the following 2009 aerial photograph.



Restore Cross Section, Riparian Restoration, Wood Placement (green line highlighted with magenta) The proposed treatment area (green line highlighted with magenta) encompasses approximately 1,400 lineal feet of Lower Whittle Creek. Proposed restoration includes construction of a more suitable channel cross section, establishment of woody riparian vegetation, and installation of wood structures. To restore the channel cross section, dredge spoil material would be excavated to create 6-8 foot wide floodplains along both sides of the creek and shape the remaining bank to a stable grade (2:1). Spoils could be transported to a suitable stockpile location or spread over adjacent dredge spoils. Two approaches to LWD should be considered. The first involves installing structures during cross section restoration. This would provide the opportunity to incorporate a channel sinuosity element during excavation. The second approach would involve delaying wood placement until riparian vegetation becomes established to a point that it would facilitate structure stability (anchoring). Riparian restoration would focus on getting native vegetation suited to the site conditions established. This would consist of planting a primary matrix of Red Alder and Black Cottonwood along the channel. Red Alder should be planted on the floodplain and up the adjacent slopes 2-3 feet of increasing elevation. Black Cottonwood poles should be considered for all the upslope planting sites. Bare root or potted plant materials should be auger planted. Auger depth should be to ground water depth or the maximum depth obtainable by hand auger or skid steer mounted auger. This approach will help identify any inhibitive layers (compact mudflow or lenses) that may preclude successful plant establishment. Potted plants will allow for some limited inclusion of organic material into the prepared planting site. Cottonwood and Willow planted as poles (cuttings) should be planted by water-jet auger. This will allow a planting hole to be mined in the dredge material in order to get the cutting within close proximity to ground water, avoid undue abrasion of the cutting during planting, and help ensure good plant-soil contact after planting. A cooperative effort with the Castle Rock High School horticulture program should be explored to provide plant materials and planting assistance. Potted plant material should be at minimum 2-gallon container stock. Cuttings can be collected on site and should range from a half-inch diameter up to 2-inch diameter material with length dependent on water-jet auger depth. Wood Placement and Riparian Restoration (yellow line highlighted with green) The proposed treatment area (yellow line highlighted with green) encompasses approximately 800 feet of Lower Whittle Creek. Proposed restoration consists of working with naturally established riparian vegetation by placing tree starts to further increase development of riparian function. The two areas have naturally developed floodplain features over the last couple of decades. Red Alder has naturally established. Placement of wood structures amongst the existing Red Alder is proposed to increase hydraulic complexity. This will result in channel scour that will create pools and continue development of floodplain features. The intent is to capitalize upon existing woody vegetation as anchors for wood structures. Vertical piles would be utilized to augment natural anchor locations and assist with targeted scour pool spacing of 3-5 channel widths. Riparian restoration in these areas will include additional Red Alder establishment in open areas while focusing on introducing native shrub species amongst the existing trees and planting Black Cottonwood on upslope areas. The planting plan is the same as that proposed above including auger planting and both potted stock and cuttings. Wetland Opportunity (blue line) The area designated by a blue line encompasses about 200 feet of tributary drainage to Lower Whittle Creek. A major resource concern in Lower Whittle Creek is stream flow in late spring/early summer as juvenile salmon are migrating towards the Cowlitz River. Low flows coupled with subsurface flow strands juvenile salmon. The lack of deep water refuge (pools) further reduces the survival of stranded fish. An opportunity that should be explored includes the restoration of a wetland complex similar to what existed prior to the eruption of Mount Saint Helens. The right bank fork designated by a blue line


presents an opportunity that should be examined further. The concept would include excavation of a wetland feature that could store water and slowly release it to Whittle Creek as creek flow diminishes. Wood Placement (orange line) The area designated with an orange line includes approximately 300 feet of Whittle Creek. Although emphasis is placed on Lower Whittle Creek an opportunity exists to place wood structures within a short reach upstream of PH10 where Red Alder is currently providing improved riparian function. This project would include the placement of wood structures amongst the existing Red Alder to increase hydraulic complexity (flow convergence/divergence and resulting scour pools). As described for the section designated by a yellow line highlighted with green, wood structures would be inserted where existing trees are located for anchoring. Vertical piles would be used to augment anchoring locations to allow for a targeted scour pool spacing of 3-5 channel widths. Proposed Mitigation The opportunities identified for restoration in Lower Whittle Creek offer a robust opportunity for a step-wise approach at salmon recovery in this watershed. The City of Castle Rock proposes to select and implement a portion of the restoration activities based upon “impact” of the proposed boat launch structure and resources available to implement mitigation. Any increment of implementation toward a comprehensive plan to address resource concerns on Lower Whittle Creek will result in meaningful salmon recovery in the watershed. The effort presented herein will in no way attempt to decipher the monetary value of implementing restoration practices in Whittle Creek. The proposed activities should directly address resource concerns that are reducing smolt-to-adult salmon return rates and would therefore have a significant value-added economic benefit. The proposed mitigation will instead attempt to balance the area of potential impact at the boat launch with the area benefitting from the mitigation projects. The boat launch site impact includes construction of a rock groin that will directly impact approximately 3,000 sq. ft. of Cowlitz River aquatic habitat. Even though the structure is considered an impact, it does serve to add habitat diversity and quantity to the Cowlitz River ecosystem. The City of Castle Rock offers the following proposed mitigation projects to offset “impacts” of the boat launch structure. The City proposed mitigation will continue stream restoration efforts in a generally downstream direction from existing mitigation by implementing:

1) Wood structure installation in the Whittle Creek reach designated by an orange line, which includes construction of 3 wood structures. This would directly influence about 300 lineal feet of habitat or about 3,000 sq. ft. of aquatic habitat. Resulting scour will provide holding/resting habitat for migrating adult salmon and rearing habitat for downstream migrating juvenile salmon.

2) Wood structure installation and riparian improvements identified by the yellow line highlighted with green reaches. This would consist of an estimated 7 wood structures. This would directly influence about 800 lineal feet of habitat or 8,000 sq. ft. of aquatic habitat. Riparian restoration activities would encompass a buffer area approximately 30 feet wide along each side of the channel, resulting in more than 1 acre of riparian rehabilitation. This would indirectly benefit about 2,200 lineal feet of creek or 22,000 sq. ft. of aquatic habitat.

Dave Vorse City of Castle Rock Public Works Director

Documents

City of Castle Rock Cowlitz River Boat Launch Impact Site and