DRAFT MONITORING REPORT LELAND-DOUGLAS HABITAT RESTORATION PROJECT

Transcription

1 DRAFT MONITORING REPORT LELAND-DOUGLAS HABITAT RESTORATION PROJECT Prepared for Stillaguamish Tribe of Indians Prepared by Anchor QEA, LLC 1605 Cornwall Avenue Bellingham, Washington October 2013

2 TABLE OF CONTENTS 1 INTRODUCTION Site Description ENGINEERED LOG JAMS MONITORING PROTOCOL Site Characterization Existing Geomorphic Conditions Data Collection Methods Photo Points Field Observations ELJ Structural Monitoring Bank Response Monitoring As-Built Baseline Monitoring Monitoring Schedule Reporting Requirements Investigative Action Corrective Action Documentation REFERENCES List of Tables Table 1 Monitoring Parameters, Performance Standards, and Data Collection Methods for ELJ Performance Monitoring for the Leland-Douglas Habitat Restoration Project... 7 Table 2 Stillaguamish Tribe Proposed Response for Exceedance of Monitoring Performance Standards List of Figures Figure 1 Proposed Conditions Leland-Douglas Habitat Restoration Project i

3 LIST OF ACRONYMS AND ABBREVIATIONS cfs cubic feet per second DBH diameter breast height ELJ engineered log jam mi 2 square miles North Fork North Fork Stillaguamish River Project Leland-Douglas Habitat Restoration Project Phase I RM river mile Tribe Stillaguamish Tribe of Indians USGS U.S. Geological Survey WDFW Washington State Department of Fish and Wildlife WRIA Water Resources Inventory Area Leland-Douglas Habitat Restoration Project ii

4 1 INTRODUCTION The Leland-Douglas Habitat Restoration Project Phase I (Project) is located between river mile (RM) 27.5 and RM 28 of the North Fork Stillaguamish River (North Fork) in Snohomish County, Washington. The Project consists of four engineered log jams (ELJs) in the main stem of the North Fork, as well as in a left bank side channel. The ELJs were constructed during summer 2013 by the Stillaguamish Tribe of Indians (Tribe). The following plan was developed to document the benefits and potential adverse effects of the ELJs after construction. 1.1 Site Description The Leland-Douglas site is located along the North Fork in the Stillaguamish River Basin (Water Resources Inventory Area [WRIA] 5), which is approximately 700 square miles (mi 2 ) and is the fifth largest tributary to Puget Sound (Ecology 2011). The Stillaguamish River extends from its headwaters in the Cascade Mountain foothills to the Puget Sound, where it drains into both Port Susan and Skagit Bay near Stanwood, Washington. The river consists of a north fork and a south fork that merge near the City of Arlington (approximately RM 22). The North Fork is approximately 45 miles long with flows originating near Finney Creek north of Darrington, Washington. The site is located along the left bank of the Stillaguamish River and is accessed from Highway 530 (Arlington-Darrington Road), approximately 10 miles east of the Town of Oso (Figure 1). The property is a former mill (Fortson Saw Mill) that operated throughout the early 20 th century. The Washington State Department of Fish and Wildlife (WDFW) later acquired the property and operated ponds for coho and chum smolt production. The ponds and remnant infrastructure from the early mill are found on the property. In addition, an abandoned BNSF railroad alignment bisects the property and is part of the Whitehorse Trail that extends from Arlington to Darrington along the North Fork. The property is vegetated with second-growth timber woody understory vegetation. A side channel is located along the left bank that provides prime juvenile salmonid rearing habitat. The Project is located in the mainstem just downstream of Fortson Hole, a natural pool located at the river meander. Leland-Douglas Habitat Restoration Project

5 2 ENGINEERED LOG JAMS Four ELJs were constructed during the summer of 2013 (ELJs No. 2 through No. 5); their general locations are described below, as well as the specific geomorphic and habitat goals of the constructed ELJs. The ELJs are numbered upstream (ELJ No. 1) to downstream (ELJ No. 5) through the restoration reach. ELJ No. 1 (Pile-braced ELJ) was not constructed as part of Phase I, but will be reviewed as part of Phase II planning and design. ELJ No. 2 (Bar Apex ELJ) is located on the left bank of the mainstem at the side channel inlet. The purpose of this ELJ is to provide hydraulic refuge for juvenile and adult salmon, promote pool formation to provide holding pools for adult salmon and improve hyporheic upwelling, and promote natural geomorphic processes to split flows, as well as promote year-round flow in the side channel. ELJ No. 3 (Pile-braced ELJ) is located in the side channel along the left bank. The purpose of this ELJ is to interact with flow in the side channel, providing adult and juvenile habitat year round; promote natural processes to get better floodplain connection with floodplain and side channel; and provide hydraulic refuge for juvenile and adult salmon during high-flow conditions. ELJ No. 4 (Bar Apex ELJ) is located near the left bank in the mainstem at the downstream outlet of the side channel. The purpose of this ELJ is to promote split flow conditions and habitat complexity; promote pool formation to provide holding pools for adult salmon and improve hyporheic upwelling; and provide hydraulic refuge for juvenile and adult salmon. ELJ No. 5 (Bar Apex ELJ) is located near the left bank in the mainstem channel and is the downstream-most ELJ. The purpose of this ELJ is to promote split flow conditions and habitat complexity; promote pool formation to provide holding pools for adult salmon and improve hyporheic upwelling; and provide hydraulic refuge for juvenile and adult salmon. Leland-Douglas Habitat Restoration Project

6 3 MONITORING PROTOCOL The monitoring protocol consists of monitoring parameters in the following two categories: ELJ: Assess the structural integrity of the ELJs Bank Response Monitoring: Assess the effect the ELJs will have on bank characteristics through the Project reach (downstream of the Fortson Hole) along both the right and left bank For each of the parameters, a measurable attribute has been developed that will be measured or estimated using an evaluation technique that is specified in Table 1. Data will be collected either by field observation, field measurement or photo observation. To measure the success of the ELJs, performance standards were also developed for each measureable attribute, where applicable. Some channel morphology measurable attributes fall under the category of reach observations that will not be used as a performance measure for the Project, but will provide general information about channel response to the ELJs. 3.1 Site Characterization The Leland-Douglas reach is located within a somewhat confined segment of the North Fork. Throughout this reach, and within the greater vicinity, the North Fork has a low gradient with a general meandering planform, and it flows within a wide valley. The hydraulic and habitat complexity are limited, with minimal to no instream wood and cover at the site. At the upstream end of the reach, the North Fork flows into a large, deep-water pool at Fortson Hole (left bank) formed by large rock placed decades ago to protect the adjacent railroad grade. Downstream of the meander apex, the North Fork flows along an armored right bank that protects a group of rural residential properties. The thalweg of the river is located along the toe of the riprap, and lateral unvegetated gravel/cobble bars are present along the channel margins. Along the left bank, a side channel (approximately 400 feet in length) cuts through the left bank floodplain area. The side channel is hydraulically connected to the mainstem except during low-flow conditions. While the left floodplain is not armored or leveed, the river has become entrenched along the riprap at Fortson Hole and the riprap placed along the residential properties, and little channel movement or natural habitat creation has occurred over the past few decades through the Project site. Leland-Douglas Habitat Restoration Project

7 3.1.1 Existing Geomorphic Conditions Upstream of Fortson Hole, a side channel (or flow pathway) is located through the right bank floodplain. If erosion continues along this bank, a full or partial river avulsion into this side channel may occur. If this flow pathway becomes active, the pathway may place numerous residences and associated structures at risk for greater flooding and erosion. The Project will not influence the ongoing river processes occurring upstream along this bank and will not have any effect on future flooding or erosion associated with this channel. The timing and risk associated with this side channel activation are uncertain and have not been studied in detail. Downstream of this potential channel pathway, riprap has been placed along the right bank to prevent lateral erosion into the right bank floodplain where residential structures are located. Numerous side channels exist within the forested left bank floodplain that is lower in elevation than the right bank floodplain. In addition, Little French Creek flows to the west through the floodplain, and flows into the North Fork downstream of the Project site. Lateral erosion along the left bank is occurring downstream of Fortson Hole. If this erosion continues, the river could move into the left bank floodplain and occupy one of the existing side channels or Little French Creek if unidirectional migration occurred over an extended time period. 3.2 Data Collection Methods Photo Points Photographs will be taken at established points and will be taken at these identified locations throughout the duration of the monitoring period. The photographs will be used to assist in evaluating the parameters identified in Table 1. The purpose of these photographs is to provide an overall view of the channel and bank areas and will serve as documentation that may be used to assess changes in the ELJ structures, bank condition, and channel over time. Photographs collected as part of the monitoring events will be in digital format and will be taken at locations designated in this monitoring plan and of features/items identified in Table 1. The camera used for photography will be equipped with lenses ranging from wide angle to telephoto. Leland-Douglas Habitat Restoration Project

8 3.2.2 Field Observations Observations will be collected per the attribute measurement units listed in Table 1. These observations range from a visual observation to an actual measurement using task specific instruments ELJ Structural Monitoring The primary goal of the structural portion of the monitoring plan is to identify and document the stability and integrity of ELJs. ELJs are different from traditional instream structures because they are primarily organic and, therefore, pose certain unusual maintenance challenges, such as the assessment of decay and settlement. There are six measurable attributes that will be assessed to indicate structural failure or overall integrity. The following gives brief description of how the measurement of these attributes will occur. Size change will be measured by surveying the length, height, and width of the structure. These measurements will be taken in the field and used to estimate changes. Large increases or decreases in structure size may alter the intended function of the ELJ. Backfill will be measured in the field at each ELJ. Visual observations will be used as well. These data will be compared to prior monitoring events to determine if the backfill volume has changed over time. Wood loading (quantity) will be approximated by estimating amount of racking material that has accumulated over time. This will be determined by field estimate from visual and photographic observations. Scour pools will be measured through on-site measurement and observation. Scour pools should form at all the ELJs engaged by the river. The estimated area and depth will be documented. Pool depth can be measured either from an in-water survey (if depth is greater than 6 feet) or by using a survey rod for measuring depth at different locations throughout the pool, if the pool is sufficiently shallow. The maximum residual pool depth will be measured by whatever means is most appropriate. Pool depth will be measured in at least three locations to account for variability in depth. The estimated width and length will be estimated from the banks if measurement is not possible. Leland-Douglas Habitat Restoration Project

9 Woody vegetation will be evaluated based on survivability of native vegetation on the ELJs. Additionally species type and their relative size will be noted. Data collected will also include the location of the vegetation: growing directly on the logs (i.e., nurse logs), on the backfill, or on the banks. This will be observed in the field and can be estimated from photographs taken at the site. Settlement of structure will measure any horizontal settling of the structure, which will be noted through visual observation and photographs. Settlement in the structure will be determined during field observations by the change between the baseline condition and the current condition Bank Response Monitoring The goal of the bank protection monitoring will be to evaluate bank response along the right and left banks through the project reach. Bank characteristics will be documented throughout the Project reach with segments characterized as stable or unstable. Bank conditions will be documented with photos, field measurements, and observations. When possible, a handheld GPS unit will be used to characterize bank condition characteristics and the locations. Other bank metrics will be collected, including bank height and bank materials. The channel thalweg location will be noted during all monitoring events. The location of the thalweg in relation to the distance to the banks will help track potential stable and unstable areas. Trees located along the right bank that are growing in the existing levee (greater than 12-inches diameter breast height [DBH]) will be inventoried as part of the monitoring program, including baseline monitoring. The trees meeting the 12-inch DBH will be monitored once annually during the low-flow monitoring event. Leland-Douglas Habitat Restoration Project

10 Table 1 Monitoring Parameters, Performance Standards, and Data Collection Methods for ELJ Performance Monitoring for the Leland-Douglas Habitat Restoration Project Monitoring Parameter ELJ Structure Monitoring ELJ Size Backfill Wood Loading Scour Pool Woody Vegetation Settlement Bank Stability Trees in Levee Measurement Area (square feet) and maximum height above grade (feet) Estimate of backfill volume (cubic feet) Obstructed width Maximum depth, width, length (feet) Vegetation type and density estimate Decrease in ELJ height measured above the channel bed or bar as compared to the baseline condition structure (feet) Bank characteristic monitoring Stable and unstable Trees greater than 12 inches DBH Performance Standard 1 Greater than 50% increase in area (length and width) Greater than 30% of loss of backfill volume When obstructed width exceeds 2x the structure design width Greater than 5 feet (from baseline asbuilt pool maximum depth) Greater than 80% survival by Year 3 Settles greater than 2 feet (vertical) Observed negative effect Count Data Collection Method(s) Direct measurement, field photo Direct measurement, field photo Direct measurement, field photo Direct measurement Direct measurement, field photo Direct measurement, field photo Direct measurement, field observation, field photo Direct measurement Notes: 1. Performance standards based on the structure designs and professional judgment 3.3 As-Built Baseline Monitoring As-built baseline data will be collected immediately following Project completion. The first year of baseline data will be used to validate and adapt the protocols included in the Leland-Douglas Habitat Restoration Project

11 monitoring plan. Photographic points will be established during the baseline monitoring and will be used throughout the monitoring plan duration. At a minimum, photo points will be established to capture each ELJ and key bank and channel locations. As-built monitoring will occur immediately after completion of ELJ construction (within 60 days of Project completion; i.e., date when work below the ordinary high water mark is completed). 3.4 Monitoring Schedule Monitoring will occur annually for a 5-year period beginning with the first calendar year following completion of construction, 2014 (Year 1). Monitoring will occur at approximately the same time of year each year and will occur twice annually, once during the lower flow period and once during the higher flow period. At the site, the lowest average monthly flows occur during the late summer and early fall (late August through early October) prior to the wet season. Observations at low flows will allow visual observations of a greater portion of the structure and easier collection of some of the monitoring parameters. Peak flows (high flows) monitoring will occur in the winter and spring. Monitoring will target a high-flow period, where flows in the river exceeds 6,000 cubic feet per second (cfs; annual flood is estimated at 8,620 cfs). In addition, monitoring will occur during extreme high-flow conditions (i.e., when flows exceed 30,000 cfs). Visual monitoring of the ELJs will be conducted within 48 hours. The extreme high-flow monitoring information will be included in the subsequent year s monitoring report (see Section 3.5 for annual reporting requirements). Real time flow data are available from the North Fork gage near Arlington (U.S. Geological Survey [USGS] Gage ). Peak flow monitoring is important to determine how the ELJs are interacting with high flows and impacting local banks. High-flow observations and field data will be documented and kept on file at the Tribe s Natural Resources Department Office. 3.5 Reporting Requirements Annual monitoring reports will include field observations and measurements (see Table 1), a data analysis, an interpretation and discussion of the monitoring results, and any extreme high-flow event monitoring information. The annual reports will include other pertinent Leland-Douglas Habitat Restoration Project

12 data and information, including but not limited to photographs, GPS data, and accounts of visual data observations. The reports will provide a discussion of the performance of the ELJs and any concerns regarding the right bank. Recommended contingency measures and maintenance actions will also be included in the report if necessary. Reports will be completed in electronic PDF format. The Tribe will keep all monitoring data, photos, and reports in their files and records. 3.6 Investigative Action If the Performance Standards outlined in Table 1 are exceeded, the cause of the exceedance will be investigated in the field to determine what the appropriate proposed response or corrective action will be (Table 2). No action may be taken if it is deemed that no negative effect is occurring as a result of the performance standard exceedance. 3.7 Corrective Action Documentation In the event that investigative action (see Section 3.6) indicates that measures need to be taken by the Tribe (such as exceedance of the monitoring parameters in Table 1), the Tribe will consider steps of action for potential repair of ELJs or the bank or other actions. For documentation purposes, the Tribe will prepare a Contingency Response for any corrective action measures taken. The corrective action response will document the following information: Description Location, size, and extent of finding Potential impacts Recommended corrective measures Recommended timing of corrective measures Follow-up monitoring of recommended corrective measures Stakeholder and property outreach (as necessary) Additional applicable information Leland-Douglas Habitat Restoration Project

13 Table 2 Stillaguamish Tribe Proposed Response for Exceedance of Monitoring Performance Standards Monitoring Parameter ELJ Size Backfill Wood Loading Performance Standard More than 50% increase in area (length and width) More than 30% of loss of backfill volume When obstructed width exceeds 2x the structure design width Evaluation Methodology for Performance Standard Exceedance 1 Field Evaluate: Wood accumulation on the structure Log quantities and log size (length and width) Secondary effects such as bank stability, structure settlement, and scour Field Evaluate: Loss of backfill Evidence of piping through the structure Amount and location of erosion as a result of water piping Field Evaluate: Channel and banks changes as a result of wood loading Changes to structure footprint Proposed Response or Corrective Action Timing of Corrective Action 2 Reduce Structure Size. The Tribe will consider reducing the size of the structure by removing wood that has racked and/or accumulated on the structure. No Action. No action warranted because the change in structure size has no negative effects. Replace/Add Backfill. The Tribe will consider replacing the backfill with in-kind material (i.e., design specification size). The backfill will be replaced to match the original asbuilt volume (height, width, and length) extents. No Action. No action warranted because the loss in backfill volume has no negative effects. Remove Wood. The Tribe will consider removing wood that is causing an unintended effect in the channel, along the bank, or to the structure. No Action. No action warranted because the increase in wood loading has no negative effects. Wood and logs will be removed as soon as river flows allow safe access (including necessary equipment) at the ELJ(s) to allow removal. Backfill will be placed as soon as river flows allow safe equipment access at the ELJ(s) to allow placement of backfill. Accumulated wood and material will be removed as soon as river flows allow safe equipment access at the ELJ(s) to allow removal. Leland-Douglas Habitat Restoration Project

14 Monitoring Parameter Scour Pool Performance Standard More than 5 feet depth (from baseline as-built pool maximum depth) Evaluation Methodology for Performance Standard Exceedance 1 Field Evaluate: Structure settlement Structure undercutting Scour pool size and depth Proposed Response or Corrective Action Timing of Corrective Action 2 Add Logs. If necessary, the Tribe will consider adding appropriatesized logs to the ELJ to prevent the ELJ from being undercut or to add height to the structure. Add Scour Apron. Add rock or alluvium to reduce scour pool size and depth. Logs will be placed as soon as river flows allow safe equipment access at the ELJ. Woody Vegetation Settlement More than 80% survival by Year 3 Settles more than 2 feet (vertical) Field Evaluate: Vegetation health Vegetation types and varieties present Invasive species Presence of pests Beaver activity Water availability for plantings Field Evaluate: Structure height changes Key member configuration Scour pool presence Wood decay No Action. No action warranted because increase in scour pool depth has no negative effects. Re-vegetate ELJ. As necessary, the Tribe will consider planting vegetation on the ELJs to meet coverage target performance standards. No Action. No action warranted because woody vegetation targets cannot be met due to uncontrolled, natural circumstances. Add Logs. If necessary, the Tribe will consider adding appropriatesized logs to the ELJ to prevent the ELJ from being undercut or to add height to the structure. No Action. No action warranted because settlement has no negative effects. Necessary plantings will occur during the spring and early summer. Logs will be placed as soon as river flows allow safe equipment access at the ELJ. Leland-Douglas Habitat Restoration Project

15 Monitoring Parameter Bank Stability Performance Standard Observed negative effect Evaluation Methodology for Performance Standard Exceedance 1 Field Evaluate: Right bank erosion Left bank erosion Side channel activation Essential structures at risk of erosion Loss of riparian vegetation Proposed Response or Corrective Action Timing of Corrective Action 2 Repair Bank. The Tribe will consider Bank repair will occur repairing the bank where adverse during the summer lowflow erosion is occurring. period. Replant Vegetation. The Tribe will replant riparian vegetation lost due to bank erosion. No Action. No action warranted because bank stability/instability has no negative effects. Emergency actions to repair an eroding bank, by Tribe to protect essential property Vegetation will be replanted on bank areas restored by the Tribe. Notes: 1 In most cases, exceedance of the Performance Standard requires follow-up site review by the Tribe. 2 If any action is deemed an emergency action, the Tribe will consider conducting the work as soon as possible, pending any appropriate agency/permit approval and other issues such as safety and access. ELJ = engineered log jam Leland-Douglas Habitat Restoration Project

16 4 REFERENCES Anchor QEA, Design Report Leland-Douglas Habitat Restoration Project. Prepared for the Stillaguamish Tribe of Indians. Bellingham, Washington Leland-Douglas Habitat Restoration Project

17