Puget Sound Large River Delta Tidal Restriction and Wetland Mapping

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Cramer Fish Sciences proposes to develop a consistent and comprehensive spatial database of tidal restriction features (e.g., culverts, tide gates, levees, and dikes), and current and potential tidal wetland habitat extents for Puget Sound’s major large river deltas. Although numerous spatial datasets for tidal restriction and wetland habitat currently exist, these have not been synthesized into a consistent regional dataset. In addition, many datasets are incomplete or have become outdated. CFS will compile regional datasets into a consistent spatial database and use remote sensing to update and correct regional data, digitize missing features, and classify feature types and potential connectivity impacts. The resulting spatial database will be used to delineate current and potential tidal wetland habitat extents that integrate tidal restriction information developed in this proposal. The products of this project will directly support and leverage salmon recovery planning and evaluation in the Puget Sound region (e.g., ESRP’s River Deltas Learning Objectives, PSP’s Estuaries Vital Sign and Common Chinook Indicators, NOAA’s Salmon Habitat Status and Trends Monitoring Program, and WDFW’s intertidal fish passage assessments) by providing spatial data that can be used to identify and evaluate restoration opportunities, inform development and evaluation of recovery targets at regional and system scales, and identify data gaps to guide future research needs.

Project Goals and Objectives

• Compile available regional tidal restriction datasets into a spatial database with a consistent Coordinate Reference System (CRS).
• Review compiled regional datasets and remote sensing of recent aerial imagery to create a standardized spatial database of tidal restriction features for Puget Sound’s large river deltas (Figure 1) that includes updated, corrected, and missing features based on aerial imagery interpretation.
• Classify tidal connectivity impacts for mapped tidal restriction features based on feature types and aerial imagery interpretation.
• Support the WDFW’s development of field assessment protocols for evaluating barriers to fish passage in intertidal habitats.
• Ground truth and validate the remote sensing approach for identifying missing tidal restriction features, and classifying feature types and connectivity.
• Update regional datasets for current and potential tidal wetland habitat based on the synthesized and updated spatial database of tidal restriction features that integrates classifications of connectivity impacts.
• Make datasets generated as part of this project readily available through online data repositories to support regional salmon recovery planning.

Map showing the geomorphic tidal floodplain boundaries for the large river delta systems that will be used as our study area and focus of our analysis (Purple). These large river delta boundaries were delineated as part of the SHSTMP, and are nested within the full analysis extent of the program that includes nearshore and floodplain habitats. The seaward boundaries of the geomorphic tidal floodplain extend to the boundary of vegetated marsh at the delta front. The boundary extends landward within the geomorphic floodplain of each river valley to capture floodplain surfaces that could potentially be tidally flooded based on PMEP extents. Note that the landward boundary does not include maximum head of tidal influence upriver in these systems, rather the landward boundary stops where tidal flooding is likely confined to the bankfull channel system.

Data Discovery

We targeted spatial datasets that contained habitat, infrastructure, and hydrology data for estuarine and delta habitats that include features that block or potentially mute tidal connectivity. Data discovery was focused on spatial datasets for the Puget Sound region and its large river deltas but many state-wide or larger geographical extent datasets were considered. We used two primary methods for data discovery:

• Online searches focused on web-based federal, state, county, tribal, university, and non-governmental sources, and
• Data requests targeting local area experts and regional data stewards.

Online data searches and information on data sources where relevant data were found as well as potential sources where no relevant data were found were documented in a data discovery log. This information will support future updates of the data by providing information on when and what sources were reviewed for relevant data. Contact information and responses were also logged for data request to track information on data acquired from off-line sources.

Additional reference data on stream courses, land cover, wetlands, elevation, and other relevant estuarine habitat information (e.g., not a tidal restriction dataset) were compiled, documented, and considered in the regional data synthesis. These reference data support the classification of tidal wetland extents and correction of alignment and segmentation of tidal restriction features.

Hexagon Imagery Program 0.3 m 4-band aerial imagery collected during summer leaf on conditions from August to September in 2017 were used as our primary reference data for reviewing, correcting, and digitizing missing features, and classifying feature types and connectivity impacts. Other reference datasets used include:

• Google aerial imagery - Provides time series of aerial imagery that can be used to evaluate changes for a feature or reveal attributes not seen in the primary reference image.
  
• Coastal Atlas oblique shoreline imagery (DOE 2014) - Provides an oblique aerial view for some portions of the nearshore Puget Sound that can provide evidence for feature types or presence.
  
• Hill shades of digital elevation models - Provides information on the presence and topology of elevated features and channel features where features are obscured by cover or shadows.
  
• LiDAR available from the Puget Sound LiDAR Consortium - Provides information on the presence and topology of elevated features and channel features where features are obscured by cover or shadows.
  
• PEMP tidal exceedance polygons (PMEP 2018)- Provides the expected range of tidal influence and informs the potential and current wetland extent based on current topography.

Online Data Sources UW Washington State - GIS Data Spatial data from comprehensive change analysis for Puget Sound, restrictions, wetland and shoreline features Geomorphological Research Group Major local data projects and locally hosted GIS data, raster and vector datasets USGS EROS State and national USGS datasets StreamNet Watershed boundaries, fish distributions USGS NHD Elevation DEMs, flow courses, watershed boundaries UW School of Oceanography Bathymetry and topography for Puget Sound, PRISM data (waves, sediment, and other nearshore data) USGS Coastal and Marine Geology Program Interactive maps of marine data Puget Sound LiDAR Consortium LiDAR Data UW Washington State - Aerial Imagery Data Aerial imagery (4-band, NAIP, Quads, Orthos) Whatcom County County boundary, Washington WRIA boundaries, NRCA Conservation, species habitats, infrastructure Skagit County Hydrology control structures, roads Snohomish County Waterbodies, parcels, drainage networks, levees, districts King County Levees, revetments, seawalls Pierce County Levees, revetments Kitsap County Districts and boundaries, natural features Jefferson County Roads, CMZs, wetlands Clallam County Roads, streams San Juan County Roads, parcels, habitat Island County Roads, culverts, streams, parcels, diking districts WSDOT Fish passage barriers WA DOE Levee inventory, beach access points and types WA DNR Watercourses, shore zones, shoreline modifications, DNR roads Washington State Geospatial Clearinghouse Natural hazards, boundaries, economy, geology, environment, agriculture, education, imagery, health, water, transportation United States Army Corps of Engineers Levee inventory Seattle GeoData Drainage and wastewater lines, culverts and ditches, storm outfalls, swales SoundIQ Interactive maps of shoreline characteristics, including beaches, biological features, and developments Washington State Coastal Atlas Map Shoreline modifications and shoreline armoring Point No Point Treaty Council Historical Nearshore Shoreline alterations, current day habitat delineations US Fish and Wildlife Service NWI National Wetlands Inventory Data Processing Initial examination of the compiled regional data found that tidal restriction data layers varied with respect to their extent, methods, geometries, measurements, units, and documentation. Some datasets only included location data for features, while others included attributes that describe physical measurements (e.g., lengths, widths, plunge pool depths, materials used), condition (e.g., present, abandoned, maintained), or fish passage documentation for tidal restrictions. Layers also varied in the geometry (lines versus points) used to depict tidal restrictions (e.g., culverts, levees, bridges) and the spatial accuracy of features. In addition, many features were captured or described by multiple data layers that had differing alignments within small spatial scales, creating problems for regional scale analysis and selection of appropriate data layers. Such variations in data structure, accuracy, and extent limit the usefulness and usability of available datasets at a regional scale and highlight the need for a consistent regional database structure and synthesis of tidal restriction features. Therefore, we created a new data structure that streamlined information, geometry, and attribution from available regional data sources into a uniform spatial framework with key attributes that describe feature types (primary and water crossing structure), tidal connectivity impacts, key physical information, and fish passage information into a consistent spatial database structure. An example of conflicting alignments of spatial layers depicting tidal restriction features. An example tidal restriction features with a corrected alignment to a single polyline. Standardized Database Structure Tidal Restrictions All tidal restriction features in the standardized database were maintained or digitized as polylines with a single line representing the approximate elevational top or middle of the tidal restriction features with the feature’s source (e.g., digitized from aerial imagery or Unique ID from regional data source). Features were classified using the regional data and aerial imagery in a two-tiered nested structure that included a primary feature type and water crossing feature type (where applicable) as follows: Primary features Levees and dikes Roads Railways Unmapped roads Armored/filled Water crossing features Bridges and causeways, piers and docks Tide gates and floodgates (e.g., flap gates, pump stations). Tidal muting structures (e.g., self-regulating tide gates) Pipes (e.g., buried pipes, enclosed pipes and surface drainage) Open crossings (e.g., due to breaches or removed features) Unknown (e.g., feature type wasn’t documented in the regional data or feature as identified using the aerial imagery) Tidal wetlands Maps of tidal wetland habitat features were developed using the Pacific Marine and Estuarine Fish Habitat Partnership (PMEP) tidal exceedance polygons (PMEP 2018) and SHSTMP large river delta boundaries and tidal wetland habitat and feature polygon extents (NOAA 2016) as base layers. A series of steps were used to segment and classify polygons from these base extent layers using our mapped tidal restriction features into several categories including; current tidal wetlands, potential tidal wetlands, filled/developed areas, and tidal restriction footprints. Current and potential tidal wetlands were further subset as distributaries and fringe wetlands, OWS (overwater structures), or wetlands. The resulting current and potential tidal wetland network were classified by both their feature tidal connectivity and landscape (downstream) tidal connectivity and included unrestricted, partially restricted, significantly restricted, and completely restricted connectivity ratings similar to the tidal restriction feature connectivity ratings using a rules based classification system. Feature tidal connectivity describes the connectivity of an individual polygon based on only the tidal restriction features that immediately surround or define the polygon perimeter. Landscape (downstream) tidal connectivity considers the connectivity impacts of all of the surrounding and downstream tidal restriction features and wetlands that would impact tidal flow to the wetland feature. Downstream Landscape tidal connectivity was determined by the downstream restrictions or surrounding wetland features allowing tidal connectivity regardless of the presence of less restrictive tidal restrictions or wetlands that immediately surround tidal wetland features. The landscape tidal connectivity of a feature was determined by the connectivity rating of the downstream wetlands and the downstream tidal restriction features. If a restriction had a less restrictive connectivity rating than the downstream wetland, the feature was assigned the wetland connectivity rating. If a restriction had a more restrictive connectivity rating than the downstream wetland, than the wetland was assigned the more restrictive restriction rating. Decision-tree used to classify tidal restriction features Decision-tree used to classify tidal wetland features. Notes Our current most recent progress report is available here: CFS Tidal Restrictions Progress Report - December 2020 The project was contracted in 2019 and a final report will be delivered in the fall of 2021. PRISM contract and including documents

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