Puget Sound Tidal Wetland Barrier Removal Planning

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TidalBarrierPicture RanaeHolland.jpg
Cramer Fish Sciences proposes to develop a consistent and comprehensive spatial database of tidal barrier 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 barrier 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 In addition, many datasets are incomplete or have become outdated.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 barrier 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.
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Project Goals and Objectives

  • Compile available regional tidal barrier 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 barrier 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 barrier 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 barrier 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 barrier 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 including:

Primary structures

  • Levees and dikes
  • Roads and railways

Water crossing structures

  • Bridges and causeways
  • Tide gates and floodgates (e.g., flap gates, pump stations).
  • Tidal muting structures (e.g., self-regulating tide gates)
  • Culverts (e.g., open culverts that do not have a gate or muting structure)

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 barrier 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 barrier 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, barriers, 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, sedimentparticles of clay, silt, sand, gravel, or cobble, transported by water, are called 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

Preliminary Data Processing

Initial investigations found that tidal barrier data layers varied with respect to their extent, methods, geometries, measurements, units, and documentation. In addition, many features are captured or described by multiple data layers that may have differing alignments within small spatial scales, and this redundancy creates 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 barrier 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.

Standardized Database Structure
All features in the standardized database will be maintained or digitalized as polylines with a single line representing the approximate elevational top or middle of the tidal barrier features and classified in a two-tiered nested structure with the feature’s source (e.g., aerial imagery or Unique ID). The first tier will include roads and railways, and dikes and levees. The second tier will include water crossing structure type, if applicable. Water crossings are defined by the presence of connectivity and flow under a solid feature (e.g., road, railway, or dike or levee), as identified by aerial imagery or regional data. Feature sources (regional data or aerial imagery), type, connectivity, fish passage, fishway, and certainty ratings will be recorded for all features. Additional information on the database structure will be provided as protocols are finalized.

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An example of conflicting alignments of spatial layers depicting tidal barrier features.
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An example tidal barrier features with a corrected alignment to a single polyline.