Meadowdale: Informing Puget Sound coastal stream restoration

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The Meadowdale Estuary Restoration Project is the first coastal stream mouth restoration project along the railroad-impacted shoreline of Puget Sound. The restoration project replaced an undersized culvert through the railroad embankment with a 128-foot long bridge and excavated a 1.3-acre estuary upstream of the railroad embankment. This regionally significant restoration project represents a unique opportunity for future stream mouth restoration along the railroad and on sediment starved shorelines throughout the Salish Sea.

The overarching ecological goal of this project was to restore the estuary of Lund’s Gulch Creek, including natural sediment and hydrologic processes in order to provide high-functioning, sustainable rearing habitat for non-natal juvenile Chinook (listed as threatened by the Endangered Species Act), as well as Coho (O. kisutch) and chum salmon (O. keta), coastal cutthroat trout (O.clarkii clarkii), and other fish species, within the park setting. The complexity of estuarine ecosystem processes coupled with substantial capital investments and great uncertainties concerning restoration effectiveness highlight the need for restoration effectiveness monitoring. Despite the recognized importance of understanding restoration effectiveness, monitoring is not frequently a priority component of restoration project budgets or may not be included at all. The emphasis on “moving dirt” with an “if we build it, they will come” approach has contributed to continued uncertainties around estuary restoration effectiveness. Where monitoring is funded, such efforts are frequently insufficient in spatial extent, temporal duration, sampling frequency, and/or monitoring scope to detect restoration responses that can be used in a meaningful way to inform restoration science, design, and management.

This ESRP/Learning Program funded project will investigate the ecological and geomorphic outcomes of the Meadowdale Park estuary restoration project in Edmonds, WA to inform the siting and design of future coastal stream mouths.

Background[edit]

In 2023, Snohomish County Department of Conservation and Natural Resources completed construction of the Meadowdale Beach Park and Estuary Restoration Project. The project transformed the site to restore fish passage, improve salmon habitats, increase the site’s resilience to climate change, and improve the park experience and safe access to the Puget Sound shoreline. The primary components of the habitat restoration project were the replacement of an undersized 6-foot-wide culvert with a multi-span railroad bridge to create a 90-foot-wide channel opening at the mouth of Lund’s Gulch Creek, the excavation of a large estuary immediately upstream from the Burlington Northern Santa Fe (BNSF) railroad crossing, and an expanded tidal channel downstream of the railroad crossing. Native riparian planting and large woody debris installation in the estuary and stream further improve habitat conditions. The project restored estuary habitat to benefit salmon originating in Lund’s Gulch Creek as well as juvenile salmon migrating to the site from other river systems. A primary objective of the restoration was to improve habitat for rearing by juvenile Chinook salmon (Oncorhynchus tshawytscha) which are listed under the Endangered Species Act. In addition to salmon, the project aimed to benefit other fish and wildlife who use estuary habitats and restore fluvial, estuarine, and coastal processes in the project area.

Project construction began in 2021 with the excavation of much of the enlarged estuary. In 2022, the new railroad bridge was installed and the rest of the estuary excavation was completed. Important habitat restoration refinements were made in 2023 so that the constructed project more fully matched the engineer’s final design. The Meadowdale project is regionally significant due to the railroad bridge component and the extent of estuary habitat restoration at the site. This is the first restoration in Puget Sound that included replacing a railroad crossing to improve habitat restoration and fish passage in a larger project. Another aspect of regional significance is the repurposing of a substantial portion of the park area near the railroad from a recreational focus to a habitat focus.

Snohomish County and multiple partners are committed to monitoring the site and evaluating the effectiveness of the restoration. A 10-year effectiveness monitoring plan was prepared to guide the monitoring program. The monitoring plan was developed with input from a monitoring workgroup of experts convened by Snohomish County. As this is the first stream mouth restoration project along the Puget Sound shoreline impacted by the BNSF railroad, effectiveness monitoring is particularly important to inform the design of future restoration projects at other stream mouths. In addition, the effectiveness monitoring provides essential information to document the benefits and sustainability of investments by Snohomish County, the grant funding programs that contributed to the restoration, and to BNSF Railway, which controls the right-of-way.

Project Goals[edit]

A primary goal for the restoration is to improve habitat accessibility and quality for juvenile Chinook salmon. Investigation of the degree to which juvenile salmon use the site compared to pre-construction will increase our understanding on how non-natal habitat restoration benefit juvenile Chinook salmon. To this end, we will be conducting fish (beach seine and electrofishing) and invertebrate (neuston tows and stomach lavage) surveys to monitor fish presence and prey availability in order to assess habitat suitability.

The upper estuary and railroad bridge were designed to be especially large to accommodate future increases in water levels from sea-level rise and to allow space for the site to adjust naturally once sediment processes are re-established. Sediment dynamics will be monitored to understand how the upper estuary and the creek outlet monitoring areas adjust over time due to the re-established sediment transport and depositional processes associated with the wider estuary and railroad bridge opening. The monitoring will help inform the size and design of future restoration projects to accommodate creek outlet, estuary, and sediment dynamics. To document how the configuration of the lower estuary changes following restoration, specifically the pocket estuary area, (i.e., the protected habitat landward of the beach berm) and to inform how restoration of the stream mouth benefits both the lower estuary and adjacent nearshore areas (i.e., on-site and off-site locations) drone flights, RTK-GPS beach profiles, time-lapse photography, and sediment tracking will be used to collect data on sediment dynamics.

This project will address the following questions with the overall goal to understand the effectiveness of the restoration effort:

Sediment Dynamics and Habitat Area in Upper Estuary and Creek Outlet

During low tide and typical spring flows, do stream flows in the creek outlet and upper estuary get transported through one channel or multiple channels, and does the location of channel(s) change over time?

On an annual basis, what changes in elevation occur in the upper estuary related to sediment deposition or erosion?

Sediment Dynamics in Lower Estuary and Adjacent Nearshore

Will the lower estuary channel routed to the north of the railroad bridge as part of the construction remain in that alignment or shift around?

Will the area of protected pocket estuary habitat and the length of the low flow channel change over time?

Will changes to the delivery of sediments and water from the stream and upper estuary lead to adjustments in the shape of the delta in the lower estuary?

Will the adjacent nearshore area to the north receive sediment from Lund’s Gulch Creek that results in higher intertidal elevations waterward of the railroad embankment?

Fish Use

Are non-natal juvenile Chinook salmon using the restored habitats (lower estuary, upper estuary, creek outlet, and lower Lund’s Gulch Creek)? If so, which portions of the project area or specific habitat features are they using more frequently or in greater numbers?

Are non-natal juvenile Chinook salmon using the restored habitats more than the adjacent nearshore habitats?

Is there a seasonal timing and/or size difference between non-natal Chinook salmon in the restored habitats compared to the adjacent nearshore habitats?

Are other salmon and trout (i.e., not Chinook salmon) using the restored habitats?

What river system(s) do juvenile Chinook salmon using the restored habitats originate from?

Are other nearshore fish, including juvenile and adult forage fish, using the restored habitats?

Approach[edit]

Data Collection

Bi-weekly fish sampling will be conducted mid-February through June from 2024-2025. Electrofishing will be conducted at low tide in the stream channel and embayment, and beach seining at high tide in the nearshore area.
Biological data collection started in February 2021 with fish data collection and will expand to include the collection of plankton samples, invertebrates from fallout traps, juvenile salmon stomach content, and DNA samples of juvenile Chinook. These samples will be taken in conjunction with fish sampling.
Aerial imagery will be collected two times a year, at a tidal elevation of 0’ or less.
Beach profiles will be collected 2 times annually before/after a UAV flight and additional data collection will be conducted after significant climatic events, heavy precipitation and/or wind storms which may significantly alter the beach and estuary configuration.
Two solar powered time-lapse cameras have been installed at the site, one on the bluff overlooking the shoreline area and a second on the outskirts of the estuary embayment on the landward side of the railroad. Imagery from the time-lapse camera will be used to make qualitative observations of beach morphology changes and events that have caused significant changes in the beach and estuary morphology.
A VanEssen Instruments CTD Diver sensor was deployed in the embayment area to measure continuous water quality parameters such as, temperature, water level (pressure), and salinity.
In the fall of 2024, RFID PIT Tagged sediment will be used to track travel times and distances for different sized sediment classes to determine sediment transport rates and direction of travel, which is important to determine the fate of updrift and stream sediment to the restored estuary embayment.

Planned Analysis

The analysis of fish use will entail statistical analysis of species abundance and CPUE (catch per unit effort) within the nearshore and pocket estuary habitats from 2021-2025. Biological sample analysis will include:

Identify plankton assemblages and proportion inside the estuary and the adjacent shoreline to determine prey field for juvenile salmon.
Determine what terrestrial invertebrates are available to juvenile salmon within the estuary.
Evaluate stomach content samples to determine if juvenile salmon are consuming prey from the restored site.
Process DNA samples of juvenile Chinook to determine river of origin utilizing the restored system to identify which populations benefit from restoration efforts along this portion of the railroad corridor.

Sediment tracking will make use of several approaches to quantify rates and processes driving sediment transport, characterize habitat change, and gather important validation data for modeling sediment transport across estuaries, inlets, and beaches. The sediment tracking component includes:

Aerial imagery and generation of digital surface models (DSM) from UAV flights for tracking changes in beach elevations, surface sediment class sizes, and changes in the beach and estuary configuration.
Beach and estuary embayment RTK GPS profiles to generate and georeference digital terrain models (DTM) and track changes in beach profiles, volume changes, and to classify substrates in aerial imagery and UAV derived DSMs.
Tracking of RFID PIT tagged sediment to determine transport dynamics and rate of transport of varying sized clasts across the study area. The deployment and retrieval locations will be used to evaluate how the combination of coastal and fluvial processes move materials through the system. Maps of sediment transport trajectories will be generated with the surveys of the located clasts and related to transport mechanisms (e.g., tides, waves, winds, stream discharge) and used to test models.
Sediment mapping and classification will be conducted utilizing a combination of substrate type recorded during RTK GPS beach profile surveys as well as supervised classification and machine learning approaches utilizing remote sensed aerial imagery from UAS surveys and time-lapse imagery from fixed cameras

The analysis of the geomorphic data collected will focus on estimating the volume and rate at which sediment is transported downstream into and out of the embayment to the shoreline/stream delta. We will explore whether large sediment transport events correlate with episodic climate events and at different tides. Additionally, we will utilize the aerial imagery and time lapse camera footage to make qualitative observations about how the different processes (fluvial and coastal) interact and distribute sediment throughout the system.

Notes[edit]

This project is led by Tulalip Tribes of Washington and funded as part of an ESRP/Learning Program.
Progress reports and associated PRISM contract and documents are available online PRISM Record Number 22-1754

Please contact Todd Zackey (tzackey@tulaliptribes-nsn.gov) or Heidi Stewart (hstewart@tulaliptribes-nsn.gov) with any questions regarding this project.