Puget Sound Tidal Restriction and Wetland Mapping

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Cramer Fish Sciences will complete development of a spatial data set that describes the degree of tidal connection among Puget Sound embayments, between 2021 and 2024. This work follows the Puget Sound Large River Delta Tidal Restriction and Wetland Mapping effort in Puget Sound river deltas. This work is anticipated to support rapid assessment, prioritization and planning for restoration.

This project will address multiple regional data gaps for several regional salmon recovery programs (including National Oceanic and Atmospheric Administration's (NOAA) Salmon Habitat Status and Trends Monitoring, Puget Sound Partnership's (PSP) Common Indicator and Vital Signs, Washington Department of Fish and Wildlife’s (WDFW) Fish Passage Inventory, and Estuary and Salmon Restoration Program's (ESRP) Beach Strategies) and will support program goals and regional restoration planning at a regional scale for Puget Sound. We will leverage existing protocols, datasets, and regional expertise to produce consistent regional-scale mapping products that will be readily accessible through online mapping applications to support regional restoration planning and evaluation of progress towards recovery. This project will focus on developing data to support regional monitoring and reporting of habitat status and trends for two key habitats that can influence salmon habitat; (1) tidal wetland habitats and features that influence tidal connectivity, and (2) marine riparian habitat. This page focuses on describing the efforts to map tidal restrictions and wetlands. More information about marine riparian mapping can be found on the Puget Sound Marine Riparian Mapping page.

Cramer Fish Sciences has already completed Puget Sound Large River Delta Tidal Restriction and Wetland Mapping. This contract will build off of the protocols developed in that effort to continue mapping to the entire Puget Sound nearshore.

Project Goals and Objectives[edit]

  • Update regional data discovery, inventory, and spatial database of original datasets developed from the large river delta mapping project.
  • Create a consistent and up to date regional spatial database of tidal restriction and tidal wetland features for the entire Puget Sound Shoreline.
  • Publish readily available spatial data layers for tidally influenced and marine riparian habitats at the regional scale.
  • Support regional salmon recovery and habitat restoration planning and evaluation.

Background[edit]

Puget Sound’s large river deltas and tidal wetland habitats associated with pocket estuaries, embayments, and other shoreline features provide critical rearing habitats, saltwater transition habitats, and migration corridors for salmon (Beamer et al. 2005; Beamer et al. 2018). Restoration of tidal connectivity or removal of features that block or restrict tidal processes represents a significant opportunity to increase functional and accessible tidally influenced habitat, and the area of functional (tidally connected) tidal wetland habitat is a regional salmon habitat indicator for large river deltas as well as pocket estuary and embayments in Puget Sound (see Puget Sound Partnership's Common Indicator and Vital Signs). However, many existing tidal restriction datasets are fragmented, inconsistent, incomplete, or outdated and therefore are difficult to use at a regional scale.

Significant progress was made in developing a consistent spatial database of tidal restriction and tidal wetland features through [PRISM Project #18-2250 for Puget Sound’s large river deltas. For that project, we used a combination of regional data and remote sensing to synthesize and correct regional data and map missing features. This was combined with regional review with local area experts and field validation surveys, and we found that our approach was efficient in creating a consistent, standardized, and up to date spatial database of tidal restriction features for Puget Sound’s large river deltas while also identifying and mapping many features missing from available regional datasets (≈45% of the mapped features were not included in regional data). This project will leverage the already compiled regional datasets, standardized spatial database, and remote sensing protocols to map tidal restriction features and tidal wetlands for the rest of the Puget Sound shoreline, which will create a consistent and up to date spatial database of tidal restriction and tidal wetland features for the entire Puget Sound region that will be readily accessible through online mapping applications.

Methods[edit]

For the purposes of this project, we defined tidal restrictions as man-made features (e.g., primary features including armor and fill, levees and dikes, roads and railways, and water crossing features including bridges, piers and docks, tide and floodgates, and culverts) that disrupted tidal and floodplain functions, including flood storage and conveyance, nutrient processes, and hydrologic, sediment, wood, and biotic movement (adapted from Konrad 2015). The degree to which features restrict tidal processes varies among and within feature types depending on a number of physical factors (e.g., feature dimensions, elevation, landscape position, tidal and riverine processes). Removal or improving the connectivity of tidal restriction features collectively represent the most significant opportunities to increase functional and accessible tidally influenced habitat in the Puget Sound region given the degree to which tidal wetland habitats have been lost in the region. Tidal wetland area and restoration of functional tidal wetland habitats are regional recovery goals and a Tribal Habitat Strategy key target (PSP 2016).

To achieve project goals, we will follow these steps:

  1. Review regional data with aerial imagery; synthesize, correct, and update regional data features; digitize missing features; and attribute tidal restriction features (e.g., source, type, connectivity, and status) for rest of Puget Sound shoreline.
  2. Delineate and classify potential and current tidal wetland extents using tidal restriction features, associate tidal restriction features with tidal wetland polygons, and attribute tidal wetlands based on connectivity ratings.
  3. Conduct regional review and ground truthing to update and evaluate data accuracy.
  4. Synthesize nearshore tidal restriction and tidal wetland data with large river delta databases from the large river delta mapping project.
  5. Identify water crossing features for integration with WDFW’s FPDSI database and identify crossings missing from current databases for future fish passage barrier assessment
  6. Develop guidelines to support continued review and maintenance of the regional tidal restriction and tidal wetland spatial databases.
  7. Summarize tidal restriction and tidal wetland habitat extents by geographic (e.g., Chinook Recovery Watershed, Lead Entity boundaries), connectivity ratings, feature types, and sources to support regional habitat status and trends monitoring reporting.

Data discovery[edit]

In our previous project (PRISM Project #18-2250), we compiled spatial datasets that contained habitat, infrastructure, and hydrology data for estuarine and delta habitats including features that block or potentially mute tidal connectivity from online sources and direct requests to regional data stewards (WRCO 2019). Previous data discovery was focused on spatial datasets for the Puget Sound region and its large river deltas and many datasets relevant to the rest of the Puget Sound shoreline have already been compiled. Additional reference data on stream courses, land cover, wetlands, elevation, and other relevant estuarine habitat information (e.g., not a tidal restriction dataset) were also compiled, documented, and considered in the regional data synthesis.

Data structure[edit]

We will leverage the database structure and mapping protocols developed in Hall et al. (2021) to create a streamlined database of tidal restriction polylines and tidal wetland polygons, however, we will make key updates to capture characteristics specific to the shoreline and nearshore, such as including shoreform attributes.

Tidal restrictions[edit]

Our dataset will map tidal restrictions from the shoreline to NGF polygons (in places where the shoreline does not align with the NGF), within the Beach Strategies NGF 0-200 ft polygon, within the PMEP extent, within an aerial imagery-mapped pocket estuary or embayment, and within a 200-ft buffer of the PMEP or aerially imagery mapped wetland, and an additional attribute will be added to the data so that restriction features can be attributed to denote the buffer they are located in (Figure 2). Additionally, features that extend seaward beyond the shoreline, such as piers and docks and jetties will also be mapped.

All tidal restriction features in the standardized database will be 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). All features mapped as lines in the regional data will be copied into the database, and their unique ID retained, all other features will be manually digitized with a line denoting the center of the feature as visible in the aerial imagery. Features will be classified using the regional data and aerial imagery in a two-tiered nested structure that includes a primary feature type and water crossing feature type (where applicable). Features will also be classified with a certainty rating for feature existence and type based on the feature source.

Tidal connectivity will be classified based on a combination of feature type information and interpretation of aerial imagery and supplemental data sources. Feature type information will be used to classify tidal connectivity based on assumptions given the function of the feature types. Given that aerial imagery interpretation limits our ability to classify tidal connectivity, we will use general classifications of tidal connectivity impacts. These classifications will be based on the approach used in the lower Columbia River estuary for mapping and classifying tidal wetland habitats based on tidal restriction features and function (LCEP 2019).

Tidal wetlands[edit]

Maps of tidal wetland habitat features will be developed using the Pacific Marine and Estuarine Fish Habitat Partnership (PMEP) draft tidal exceedance polygons developed in 2022, which will replace the 2018 layers (Brophy et al. 2019) which were used in the large river delta wetland mapping, as the base layers. A series of steps will be used to segment and classify wetland polygons using the tidal restriction network from these base extent layers into several categories including current tidal wetlands, potential tidal wetlands, and tidal restriction footprints.

To capture both the proximate as well as the landscape impacts of tidal restrictions, we will classify each wetland polygon according to its feature and landscape connectivity, using the same classification schema as we did to map the large river deltas. Tidal connectivity will be rated as unrestricted, partially restricted, significantly restricted, or completely restricted, established using a rule-based classification system. Freshwater flow may be present to tidal wetlands but will not be considered in the ratings as we are only examining tidal connectivity.

Tidal restriction and tidal wetland features will be assigned unique identifiers and we will be able to spatially join the datasets to create a crosswalk table relating tidal wetland features to the tidal restrictions that surround them. This will allow tidal wetlands to be evaluated by restrictions that surround them, as well as allowing tidal restrictions to be evaluated based on their associated wetlands. This will also allow for the length of restrictions to be totaled by their connectivity impacts for each individual wetland.

Project Status[edit]

Mapping is underway for tidal restriction features along the Puget Sound Shoreline. We have completed mapping for the Dungeness Chinook Recovery Watersheds (CRW) and are currently mapping the Elwha, Skokomish, and Nooksack CRWs.

Notes[edit]

  • This project was funded as part of an ESRP/Learning Program (PRISM Project #20-1941)
  • The project was contracted in 2021 and a final report will be delivered in the early winter of 2024.
  • Data products developed as part of this project will be made available through WDFW hosting and will be linked to on this page.
  • PRISM Project #20-1941 contract and documents

Please contact Jason Hall (jason.hall@fishsciences.net) or Shelby Burgess (shelby.burgess@fishsciences.net) with any questions regarding this project.

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