Provided for:

The Yakama Nation on behalf of its YKFP

Fisheries Program

P.O. Box 151, Fort Road

Toppenish, WA 98948

White Creek 191 Meadow

Habitat Enhancement Project

60% Design Report March 8, 2019

White Creek 191 Meadow

Habitat Enhancement Project

60% Design Report:

Provided for

The Yakama Nation on behalf of its

YKFP Fisheries Program

P.O. Box 151, Fort Road

Toppenish, WA 98948

Prepared by

Inter-Fluve, Inc.

1020 Wasco Street, Suite I

Hood River, OR 97031

541.386.9003

September 28, 2018

SEPTEMBER, 2018 I

Table of Contents 1. Introduction ...............................................................................................................................1

2. Field Survey ................................................................................................................................1

3. Hydrology ...................................................................................................................................3

4. Hydraulic Model .........................................................................................................................4

5. Design ........................................................................................................................................6

6. Construction – Contract documentation .................................................................................... 11

7. References ............................................................................................................................... 12

8. Appendix A: Design Drawings ......................................................................................................2

9. Appendix B: Hydraulics ...............................................................................................................3

10. Appendix: Revegetation Prescription ..........................................................................................4

List of Figures Figure 1. Photograph showing bank composition and gravel lenses 1-2 feet below top of bank. .................. 2

Figure 2. Photograph showing inset floodplain development with willow (right) following lateral bank

migration of silt dominated bank (left). ..................................................................................................... 3

Figure 3. Cross-section geometry used in HEC-RAS model. ......................................................................... 5

Figure 4. Drone photograph within the project depicting both the loss of channel length and eroding

laterally migrating right channel bank. Water flow is from the bottom of the photo to the top. .................. 7

Figure 5. Inundation map of modelled existing conditions (left) and design conditions (right) during the 2-

year return discharge. .............................................................................................................................. 9

List of Tables Table 1. Weather stations in the vicinity of the White Creek study area considered for hydrology. ............. 4

Table 2. Recurrence interval flows calculated for the project reach. ........................................................... 4

Table 3. Activity categories and risk included in the project. .................................................................... 10

Appendices Appendix A - 60% Design Plans

Appendix B – Hydraulic Model

Appendix C – Revegetation Prescription

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1. Introduction

White Creek is a 4th order tributary of the Klickitat River that provides spawning and rearing

habitat for mid-Columbia ESA-threatened steelhead and resident rainbow trout. The White Creek

191 Meadow project reach is approximately 1800 feet long within a segment of former wet meadow

that has become degraded over time. The contributing watershed area above the project reach is 45

square miles. The goal of the project is to improve the quantity of valley bottom wetlands but more

importantly, increase large wood related rearing and holding habitat in pools for resident trout and

anadromous steelhead.

2. Field Survey

Field survey was conducted October 12, 2017. The project area was walked to identify and survey

potential treatment sites, general bedload and transport characteristics, and survey cross-sections for

hydraulic modeling. Survey was completed using RTK GPS and Total Station survey equipment.

Temporary control points were established throughout the project site and permanent control along

the valley toe near a forest road and adjacent to the meadow.

Ground survey data were supplemented with pre-existing LiDAR data to produce a three-

dimensional surface of the project area. Ground survey and LiDAR data compared well. Cross-

sections for the hydraulic model were extracted from the surface where appropriate. LiDAR was

used to supplement Total Station survey, design grading, base map production and both 1 and 2D

hydraulic modelling. Field photos were used to document existing conditions, bedload

characteristics, and potential project work areas.

2.1 SITE CONDITIONS

Throughout the valley bottom, an open mixed stand of younger pine and fir exists with an

understory of fescue and other grass on dryer valley bottom surfaces. Willow, sedge, snowberry and

spirea were observed within lower and wetter areas within and adjacent to abandoned channels,

and in recent depositional areas within the eroding bank boundaries.

Eroding banks have a 1-2-foot layer of silt loam forming the topsoil. Below the silt loam, there are

variable strata of gravel lenses, dense silt/clay layers forming the lower portions of exposed banks.

The sublayers beneath the valley bottom topsoil are inconsistent along the bank margins in the

project reach. Bank margins with greater clay content appear to be more resilient than banks

composed of gravel, sand and silt. Some areas show evidence of recent bank failure.

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Figure 1. Photograph showing bank composition and gravel lenses 1-2 feet below top of bank.

The streambed at the project site currently occupies a local gravel/cobble layer that is mostly

composed of on/near site material in the lower banks and bed. Upper bank soils are silt.

Composition on stepper riffles is cobble and gravel, and 1” minus gravel and sand on gravel bars.

Willows are colonizing the tops of many gravel bar deposits, which suggests a stable inset

floodplain has formed in some areas.

The channel has incised through the meadow due to basin-scale influences outside of the project

area. The degradation likely occurred rapidly through the sandy silts in the upper soil profile, but

the stream is now nestled into the gravel cobble layer, which the stream is being worked into pools,

riffles, and bars. Little coarse grain material comes from the upper watershed, which is composed

largely of fine grained soils and to a lesser degree, sub-angular cobbles. The relatively rich supply of

cobble and gravel at the site appears to be a localized resource (site scale). The cobble is

demonstrated to be heavily utilized by spawning steelhead.

Gravel

Silt Loam

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Figure 2. Photograph showing inset floodplain development with willows (right) following lateral bank migration of silt dominated bank (left).

3. Hydrology

No stream gage data exists on White Creek to calculate peak flow statistics directly. Therefore,

regional regression equations were used to estimate peak flow hydrology at the project site. These

floods were used in hydraulic modeling to help understand channel-forming characteristics and

associated stage discharge elevations with observed vegetation and sediment deposition

characteristics.

The regional regression equations were obtained from the report titled USGS Scientific Investigations

Report 2016-5118 Magnitude, Frequency, and Trends of Floods at Gaged and ungagged sites in Washington,

which is based on data through water year 2014 (Mastin et al. 2016). Within the report, Washington

State was divided into four regions. Each watershed that has a stream gage was statistically

compared to watersheds in the same region without gages and regression equations were developed

for ungagged sites. White Creek lies on the boundary of Region 2 and Region 4, which provide

varied results. Therefore, we developed equations for both regions to determine which region best

represents the flows for the White Creek project site. Determining which region was most

representative was an iterative process completed as part of the hydraulic modeling effort and

involved comparing field indicators of channel forming discharge surveyed within the hydraulic

cross-sections, with equation results for the 2-year discharge in both regions.

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Mean annual precipitation (MAP) is used within each equation. To determine a range of appropriate

MAP values to input to the equations, average annual precipitation data was acquired from the

Western Region Climate Center, which publishes data and statistics for four sites in the region

(Table 1).

Table 1. Weather stations in the vicinity of the White Creek study area considered for hydrology.

Name Network Station # Elevation (ft) Average Annual

Precip. (in)

Glenwood 2 COOP 453184 1850 30.74

Goldendale2 COOP 453226 1700 15.49

Status Pass WDOT 457340 3116 21.98

Status Pass2 COOP 457342 2610 22.64

Through an iterative process within the modeling effort, we found that the MAP that matched most

closely with the site channel forming indicators was within the low end of the range found within

stations in Table 2 (A MAP between 15 and 22 inches) and equations developed for Region 2 were

more representative of field indicators than Region 4. Discharge used for hydraulic modelling for

existing and design conditions are provided below.

Table 2. Recurrence interval flows calculated for the project reach.

Recurrence

Interval

2-Year 5-Year 10-Year 25-Year 50-Year 100-

Year

Flow (cfs) 113 345 620 1140 1710 2420

4. Hydraulic Model

The hydraulic analysis used the U.S. Army Corps of Engineers’ Hydraulic Engineering Center River

Analysis System (HEC-RAS 5.0.3; USACE 2016). HEC-RAS is a computer program that models the

hydraulics of water flow through natural rivers and other channels. A steady-state, one-dimensional

model was run in order to perform hydraulic computations to determine channel-forming flows

within the project area by comparing hydraulically-modeled peak-flow hydrology estimates with

field surveyed channel-forming stage estimates. The existing conditions HEC-RAS model was

developed using the best available data and is a representation of the physical terrain along White

Creek and adjacent floodplain surfaces.

HEC-RAS cross-sections were spatially drawn to sample the surveyed cross-sections on the ground,

span the 100-year flood inundation extents at hydraulic controls, and traverse sites where habitat

improvements are likely to occur. Cross-sectional geometry was extracted from the three-

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dimensional topographic LiDAR used to supplement total station survey. The locations of hydraulic

cross-sections are shown in Figure 3 below.

Figure 3. Cross-section geometry used in HEC-RAS model.

The model was run in steady-state under mixed flow regime to represent peak floods on existing

conditions. The boundary conditions were set to normal depth at the average slope at upstream and

downstream ends of the study reach. Manning’s ‘n’ or roughness values correspond with various

types of land cover and channel characteristics (Table 3). Values are consistent with field

observations as well as published guidelines for channel types and vegetation conditions (Arcement

& Schneider 1989).

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Table 3. Roughness coefficients used in the hydraulic model.

Description Manning’s n

Channel, cobble bed, bars and banks 0.034

Gravel bars with sparse vegetation and discontinuous LWD 0.05

Gravel bars dense willow or woody debris 0.06-0.07

Floodplain, grass (smooth) 0.04

Floodplain, shrubs (rough) 0.10

The proposed conditions model was developed by copying the existing conditions model and

editing the geometry to represent earthwork, block obstructions, and changes in roughness to reflect

the design. Results show that water surface elevations for all floods are little changed by the

proposed actions, but largely there are small increases in stage and inundation widths. Detailed

model output comparing existing to proposed conditions is in Appendix B.

5. Design

The proposed design seeks to increase riparian wetland and instream habitat by placing imported

large wood log jams within excavated lowered banks at existing eroding meander bends and

inflections. The 191 Meadow is one of many stringer meadows that have lost channel length and

become locally incised, losing contact with former floodplain surfaces. The valley bottom became

perched and disconnected from frequent seasonal flood inundation, causing significant drying and

plant ecology changes over much of the former meadow surfaces. Areas that were once likely sedge

and willow are now grass and pine. The incision places greater pressure on channel banks, which

over time, laterally erode and re-develop new flood-prone surfaces at lower elevations that are inset

within the now abandoned former valley bottom.

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Figure 4. Drone photograph within the project depicting both the loss of channel length and eroding laterally migrating right channel bank. Water flow is from the bottom of the photo to the top.

5.1 ALTERNATIVES

In some cases, incised channels can be filled and raised up to restore connection to former floodplain

surfaces. We do not think the 191 Meadow is a good candidate for this strategy because it has

already experienced significant lateral migration, forming an inset floodplain, which would require

a large fill volume to raise the channel bed. Furthermore, there is no reasonable downstream

location for establishing a stable grade control to step down a lifted creek segment to the incised

channel downstream of the project reach.

Adding large wood in locations and configurations that would accelerate lateral channel migration

and inset floodplain development was considered but disregarded. Further meandering at the site

might expose additional cobbles, which are good for the system and steelhead, but the thick upper

layer fine soils also recruited through bank erosion would be a significant impairment to the system

and fish health.

The proposed enhancement actions are somewhat consistent with the latter alternative. The project

would create new floodprone surfaces consistent with the elevations of inset floodplains that have

been gradually developing naturally. In this way, the configuration would be consistent with the

natural process trajectory, but without introducing fines to the stream. This will increase wetland,

restore meadow connection to hydrology, increase floodplain area for fish refuge and foraging

during high water – all while preserving the hydraulic conditions that provide and maintain existing

spawning habitat.

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The project would improve future riparian floodplain by selectively excavating 0.77 acres of new

floodplain surfaces that will become inundated during 2-year discharge estimate. The new surfaces

will support willow (gravel) and sedge (silt/clay) vegetation depending on the substrate

encountered at the new floodplain surface. Based on the variability in bank substrate, we expect the

same variability in areas excavated that are adjacent to current banks. Imported trees and logs will

be used to construct large wood accumulations on the new floodplain surfaces. Portions of the large

wood will be in contact with pools on the stream.

The lowered surfaces provide inundation areas, while the large wood creates ineffective flow. The

water surface elevations of floods will not change, and the frequency of flood inundation upon the

perched floodplain will not change significantly from current conditions. However, the extent of

inundation will be markedly increased for smaller and more frequent floods (<5yr). Improvements

in floodplain inundation are evident in the comparison of existing to proposed conditions models of

the 2-year flood (Figure 5).

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Figure 5. Inundation map of modeled existing conditions (left) and design conditions (right) during the 2-year return discharge. A total of 0.77 acres of new wetland inundation will be created during the 2-year discharge.

To enhance habitat further, existing pool areas will be excavated in areas associated with bank and

valley bottom excavation sites. Large wood will be placed to provide cover habitat over existing

enhanced pools and within lowered segments of valley bottom to provide resiliency and roughness

until wetland vegetation can become fully established.

All construction work will be completed during low/no-flow conditions the project reach

experiences in the late summer. A summary of HIP activities is described in Table 4 below.

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Table 4. Activity categories and risk included in the project.

Description of Proposed Enhancement Work Element HIP III

Category

HIP III Risk Level

Log structure construction to improve main

channel habitat suitability and stability

Install habitat-forming

natural material

instream structures

2d Medium

Low floodplain enhancement to improve off-

channel habitat

Improve secondary

channel and wetland

habitats

2a Medium

Revegetation of all disturbed surfaces Riparian vegetation

planting

2e Low

5.2 DESCRIPTION OF PERFORMANCE/ SUSTAINABILITY CRITERIA FOR PROJECT ELEMENTS

AND ASSESSMENT OF RISK OF FAILURE TO PERFORM, RISK TO INFRASTRUCTURE,

POTENTIAL CONSEQUENCES, AND COMPENSATING ANALYSIS TO REDUCE UNCERTAINTY

Infrastructure and flood risk

Imported logs specified for the project will be self-stable during floods up to the 100-year flood.

Although each log could be expected to shift during a large flood, it would not move a significant

distance from its original placement due to its length, weight, and root wad. The introduced wood is

expected to somewhat increase side channel scour and floodplain complexity over time. There is no

infrastructure in the area that can be impacted. An existing forest road will be re-located to the toe of

the valley slope. Although the road can be flooded, there is no increase in flood hazard compared to

existing conditions.

Design criteria

Design criteria for large wood are as follows:

Wood used in this project will be naturally stable and will remain on site up to the 100-year

return peak flow.

Large wood habitat will be placed and oriented to be engaged with the creek, providing

habitat year-round, and to provide sediment sorting and small woody debris capture during

high water. Floodplain grading will increase total inundation zones. Frequency of

inundation will be at the same stage and will not change from pre-project conditions.

Risk of failure to perform

Current migration rate, planform condition and grading designs are conducive to the proposed

project. The channel is well suited to wood treatments that will provide cover habitat in existing

pools, capture small woody debris, maintain spawning gravel, pool scour and associated riparian

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complexity at low and high flows. There is very low risk that importing large wood and floodplain

grading will fail to improve channel and floodplain habitat.

5.3 STABILITY ANALYSES AND COMPUTATIONS FOR PROJECT ELEMENTS, AND

COMPREHENSIVE PROJECT PLAN

Stability analysis and computations for project elements followed professional practice guidelines

for large wood design (Knutson and Fealko 2014 and USBR and ERDC 2016), stream habitat

restoration (Cramer 2012), Stability of Ballasted Woody Debris Habitat Structures (D’Aoust and

Millar 2000) and institutional knowledge combined with professional judgment for the design of

specific project elements. The size of the large wood sourced for the project greatly exceeds the

ability of the highest discharges to move the wood. Therefore, the wood is considered self-stable

and will not require ballast.

6. Construction – Contract documentation

6.1 INCORPORATION OF HIPIII GENERAL AND CONSTRUCTION CONSERVATION MEASURES

Conservation measures will be included in construction contracting. Variances will be submitted as

required for conservation measures that are not met by the project design. No variances are

expected. The project will be constructed during the low-flow/no-flow period between August and

early-October, dependent upon observed conditions.

6.2 DESIGN – CONSTRUCTION PLAN SET

Construction design drawings will be updated as necessary to the level required for field directed

construction.

6.3 LIST OF ALL PROPOSED PROJECT MATERIALS AND QUANTITIES

Final large wood numbers (volume) will be included in future permit design phases. Imported and

placed large wood/trees are the only proposed material for the project.

6.4 DESCRIPTION OF BEST MANAGEMENT PRACTICES THAT WILL BE IMPLEMENTED AND

IMPLEMENTATION RESOURCE PLANS INCLUDING:

Site access staging and sequencing plan

Work area isolation and dewatering plan

Erosion and pollution control plan

Site reclamation and restoration plan

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7. References

Arcement, George J. Jr and Verne R. Schneider, 1989 “Guide for Selecting Manning’s

Roughness Coefficients for Natural Channels and Flood Plains”, USGS Water-Supply Paper 2339

Maston, M.C., Konrad, C.P., Veilleux, A.G., and Tecca, A.E., 2016, Magnitude frequency, and

trends of floods at gaged and ungagged sites in Washington, based on data through water year 2014

(ver 1.2, November 2017): U.S. Geological Survey Scientific Investigations Report 2016-5118, 70p.

Appendix A: Design Drawings

Appendix B: Hydraulic Model

Appendix: Revegetation Prescription