An Ecological Approach to Integrating Conservation and Highway Planning, Volume 2 (2012)

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67 A p p e n d i x A Workflow for Oregon Wetland database development, September 2009 Specification Development Develop a specification, keeping in mind how you antici- pate the wetland geodata will be used. Will it be used mostly in an ecological, outreach, or jurisdictional context? Will a Cowardin classification suffice, or will other information, such as hydrological alteration, hydrogeomorphic classifica- tion, wetland management, historic conditions, or vegeta- tion communities, be needed for detailed analysis or decision making? Having a clear picture of the database usage will help determine what types of attributes are essential and what attributes may be useful but can be populated at a later time. Creating a more extensive database that is not fully attributed can save time later. If the geodata will be used in a jurisdictional or quasi- jurisdictional context, consult with the state wetland permit- ting agency. Have attributes clearly separating field-delineated wetlands from wetlands determined from imagery or non- detailed field observation. Determine if tracking historical loss or changes is an impor- tant potential use for the database. For Oregon, the project team established a nonoverlapping wetland polygon para- digm, choosing to have the polygons represent current reality. This involves modifying or deleting obsolete polygons or attributing them as “developed.” Such a paradigm does not easily support change analysis. Embed metadata with each polygon to permit an assess- ment of their relative quality. Such information can include: who developed the polygon set; whether it was aerial-photo or field-based; whether it was field-delineated or field- observed; what year it was done; if it was aerial, what are the month and year of the imagery, and at what scale was it done? Data Set Development National Wetlands Inventory (NWI) data should form the basis for a wetland geodatabase. Obtain a geodatabase directly from U.S. Fish and Wildlife Service (USFWS) that includes polylines. The NWI online distribution center does not dis- tribute linear features (polylines). Older digitized quads often represented linear features with polylines, and although the USFWS intention is to convert these features to polygons, many areas currently have polylines. If polylines are present, buffer them to 5.0 meters total width, and burn the layer on top of the polygon layer. There are several known problems with the NWI database, including incomplete coverage and varying consistency with coverage, especially with stream networks. If there are major gaps in your statewide coverage, consider hydrography data sources as potential stopgap data: National Hydrography Dataset (U.S. Geological Survey 2012) and NHDPlus cover most of the lower 48 states and include open waterbodies and wetland-oriented features, albeit at 1:100 MBscales. Some states or regions may have hydrography data sets with attri- butes that can be cross-walked into a Cowardin classification. If large sections of NWI data are missing from your state, consider digitizating NWI paper maps, or if necessary, for their initial digitization. If digitizing, coordinate with USFWS for training and NWI development methodology. Hydrography data sets can be spatially queried to check for potential wetlands that may not have been identified in the NWI data set. For example, a marsh may have been missed in the initial NWI development because of the limi- tation of the source imagery (not ideal time of year or per- haps a drought year). Based on the experience of the project team, each polygon needs to be evaluated individually; auto- mation may introduce too many false cases. In areas with limited wetland information (for example, the NWI data are sparse or nonexistent), hydric soil data from Natural Resources Conservation Service (NRCS) soil Wetland Workflow and Data Development

68 baseline (see National Biological Information Infrastructure 2012), but there may be wetland-specific management goals not encompassed by such data sets. The Wetland Reserve Pro- gram, managed by NRCS, is an example of a land manage- ment designation specifically targeting wetland re-creation or restoration. Wetland mitigation banks are another exam- ple. Water rights permitting agencies can be consulted for per- mits to private parties for purposes of wetland re-creation or restoration. Land trusts or private conservation-oriented organizations in your state may have large wetlands under their ownership or management via conservation easements. Jurisdictions may have zoning plans that identify areas pro- tected from additional development or may have identified special natural features or areas to eventually acquire. Field-derived vegetation coverages also may be used to enhance the wetland geodata as a vegetation attribute or per- haps identify new wetlands. For example, a riparian vegeta- tion study may outline areas containing ecoregion-specific wetland facultative or obligate species. Data Set Maintenance Anticipate spending time on ongoing maintenance of the geodata. Examples of changes include development of wet- lands, wetland re-creation and restoration, and changes in estuary composition caused by sea level changes or natural disturbances. NWI geodata derived from 1980s imagery may be obsolete over large areas. Wetland management changes can occur as jurisdictions decide to change protection desig- nations or nongovernmental organizations (NGO)/land trusts obtain property for permanent protection. Using the Data In Oregon’s Willamette Valley, the project team identified pri- ority sites within each fourth-level HUC unit to encourage a focused agency and NGO effort for wetland restoration proj- ects. The team took advantage of a synthesis project by The Nature Conservancy (TNC) in Oregon, wherein TNC reviewed numerous conservation-oriented action plans and identified the best areas in the Willamette Valley to target for additional conservation. Included in the TNC synthesis project was an initial version of wetland priority sites that was done without the benefit of a wetland geodatabase. The team’s objective was to determine if the near-final TNC version was adequate or needed significant modification. The team’s wetland geodata consisted of several dozen locally based wetland inventories that replaced the NWI poly- gon coverage, along with more current information on spe- cies of concern and special wetland areas. For areas that had only NWI data, the Cowardin codes provided some informa- surveys can be helpful. With the use of the NRCS Soil Data Mart, map units with a significant component of hydric soils can be extracted. NRCS surveys typically are done at scales much broader than wetland delineations. Depending on the analysis needs, such data may be sufficient as a wetland sur- rogate, or for mapping needs, the soil data can direct one’s attention to areas for closer examination of unidentified extant wetlands. USDA Forest Service Soil Resource Inven- tory or Terrestrial Ecological Unit Inventory studies may be consulted for hydric soil areas in regions with no published NRCS soil surveys. Similar to hydric soils information, flood zone data devel- oped by Federal Emergency Management Agency (FEMA) or U.S. Army Corps of Engineers (USACE) may be useful in identifying areas of potential wetlands, where no other wet- land data exist. Flood zone data may be useful in helping determine historical wetland extent or areas for potential wetland re-creation, as many river bottoms have been altered significantly from historic conditions. Some states have mandates for natural resource inventories conducted by local jurisdictions. Such inventories likely have detailed wetland information that can replace NWI data. If used, develop an inventory boundary file to clearly designate where field-based inventories took place. Develop contacts with wetland ecologists and geographic information system (GIS) analysts in federal and state land management agencies. Agencies may have their own field- based wetland mapping reports and data. Anticipate that many older reports will not be digitized. Agencies may identify areas with special ecological significance, such as the Bureau of Land Management’s area of critical environ- mental concern, with wetlands comprising a significant portion or with wetlands being the primary purpose of designating the area. Given the physical constraints of road and highway placement, state and local transportation departments are well aware of wetlands in and adjacent to rights-of-way. State fish and game (or equivalent) departments may have field-mapped wetland information, especially for water- fowl management. If possible, it is extremely useful to establish reference wet- land sites within all ecoregions of your state. Such reference sites typically are minimally altered from presettlement condi- tions and offer a functioning condition reference for wetland restoration projects. Likewise, identifying wetlands that have unique species assemblages or host wetland-obligate threat- ened and endangered species assists in developing mitigation and conservation priorities. Most state Natural Heritage offices have spatial databases with information on wetland obligate or facultative state sensitive species. Obtain land management spatial information for your state. Data from Gap Analysis Program analyses can form a

69 areas not initially identified in the original data set and minor border adjustments to the original wetland priority site layer. References National Biological Information Infrastructure. 2012. www.nbii.gov/ termination/index.html. Accessed March 22, 2012. U.S. Geological Survey. 2012. National Hydrography Dataset. http:// nhd.usgs.gov. Accessed March 22, 2012. tion on wetland condition. Open waterbodies and riparian areas were filtered out. The team took advantage of historical reconstruction data, based on General Land Office records that suggested the presettlement extent of wetlands in the Willamette Valley. The team’s analysis combined FEMA flood zone data, current wetland density, wetlands of special con- cern (those with unique communities or that host obligate threatened and endangered species), and recent and ongoing wetland restoration projects. The analysis identified several