Puget Sound Tidal Restriction and Wetland Mapping

Efforts

Efforts describe the goal-oriented activites of workgroups

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Cramer Fish Sciences has been working to develop spatial data sets that describes tidal restriction features and tidally influenced habitats in Puget Sound. 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. We have completed tidal restriction and tidally influenced habitat mapping for the entire Puget Sound nearshore and are currently seeking expert review and feedback on the datasets. These data can be viewed and feedback provided online on the WDFW webmap or relevant datasets can be shared directly with the project team.

This project addressed 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 supports program goals and regional restoration planning at a regional scale for Puget Sound. We leveraged 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 focused 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 describes 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 built off of the protocols developed in that effort to continue mapping to the entire Puget Sound nearshore. This page provides details on this project, but more information is available on the project story map.

Project Goals and Objectives

• 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

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, 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 leveraged 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

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 wetlands and tidally influenced habitats are regional recovery goals and a Tribal Habitat Strategy key target (PSP 2016).

To achieve these goals, this project involved the following:

1. Reviewing regional data with aerial imagery; synthesizing, correcting, and updating regional data features; digitizing missing features; and attributing tidal restriction features (e.g., source, type, connectivity, and status) for rest of Puget Sound shoreline.
2. Delineating and classifying potential and current tidally influenced habitat extents using tidal restriction features and associating tidal restriction features with tidally influenced habitat polygons classifying connectivity ratings.
3. Developing guidelines to support continued review and maintenance of the regional tidal restriction and tidal wetland spatial databases.
4. Summarizinge tidal restriction and tidal wetland habitat extents by geographic region (e.g., Lead Entity boundaries), connectivity ratings, feature types, and sources to support regional habitat status and trends monitoring reporting.
5. Conduct regional review and ground truthing to update and evaluate data accuracy **This process is still ongoing***

Study area

Previous mapping efforts focused on delineating tidal restrictions within the SHSTMP large river delta boundaries and tidal wetlands in the PMEP tidal exceedance polygons within the deltas. This effort aimed to map tidal restrictions and tidally influenced nearshore and wetland habitat for the remainder of the Puget Sound nearshore.

We used the updated draft PMEP tidal exceedance polygons (PMEP 2022) as the baseline potential tidally influenced habitat extent (tidal wetland extent). The PMEP tidal exceedance extent was developed by combining NOAA's extreme water level models with high-resolution LiDAR digital elevation models (DEMs), alongside National Wetland Inventory, local knowledge, and aerial photo interpretation, to map areas subject to tidal inundation, from ocean to head of tide, including the freshwater tidal zone. The PMEP extent included both current tidally influenced habitat, and historic tidal wetlands that would be inundated based on elevation but may no longer be inundated due to human alteration (such as dikes or levees).

To complement regional datasets and to capture features that could influence tidal connectivity or processes in tidal wetland habitats, we mapped restrictions within four nearshore strata, 1) seaward to the Beach Strategies NGF shoreline, 2) within the Beach Strategies NGF 0-200 ft polygon, 3) within the PMEP extent or aerial imagery-mapped tidal wetland extent, and/or 4) within a 200-ft buffer of the PMEP tidal exceedance extent. However, to be consistent with the large river delta methods, efforts were focused on restriction features that directly abutted or intersected the PMEP, water crossings, and major roadways or railways within the study area.

Data discovery

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). We expanded those efforts to identify regional datasets that mapped infrastructure and tidally influenced habitats along the nearshore. In total between the two projects, we compiled 49 spatial datasets containing 267 vector layers mapping tidal restriction and wetland features published form federal, state, county, and tribal databases.

Tidal restrictions

Mapping tidal restrictions involved the following steps:

1. Synthesize redundant regional database features and correct spatial alignment
2. Update removed or modified features
3. Digitize missing features
4. Classify feature types and certainty
5. Classify feature tidal connectivity and certainty

All tidal restriction features were 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).

Tidal connectivity was classified based on a combination of feature type information and interpretation of aerial imagery and supplemental data sources. Feature type information was used to assign general classifications of tidal connectivity based on assumptions given the function of the feature types and 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 influenced habitats

We leveraged the methods developed in the Large River Delta Mapping project to use the mapped tidal restriction features to segment and classify tidally influenced polygons from base PMEP layer. However, we expanded these methods to better capture nearshore tidally influenced habitats. We extended our tidal wetland feature classification to include a nearshore buffer, intertidal areas, embayments and pocket estuaries, and freshwater influenced habitats such as river estuaries and small river outflows. We leveraged regional and local datasets to identify and delineate these habitats to be able to assess the impact of tidal restrictions on these different tidally influenced wetlands and nearshore habitats to support salmon recovery efforts.

Project Status

We completed mapping for tidal restrictions and tidally influenced habitats for the entire Puget Sound nearshore and are seeking input to improve the dataset to better support regional salmon and habitat/ecosystem recovery efforts.

Access the WDFW-CFS Review map here.

Notes

• This project was funded as part of an ESRP/Learning Program (PRISM Project #20-1941)
• The project was contracted in 2021, regional review is currently underway and will conclude in August 2024. The final dataset and report reflecting the results of the review will be completed in December 2024.
• PRISM Project #20-1941 contract and documents

Please contact Jason Hall (jason.hall@fishsciences.net) with any questions regarding this project.

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