Delineation Standards

Regulatory Branch, Chicago District
U.S. Army Corps of Engineers
Last updated July, 2023


  • Reference appropriate Supplements to the Corps of Engineers Delineation Manual when conducting delineation fieldwork.  In Chicago District territory, either the Midwest Supplement or the Northcentral and Northeast Supplement will be used.  Determine which Supplement should be used prior to conducting fieldwork.  

  • Use appropriate Supplement data forms, the link to Automated Wetland Determination Data Form and User Guide, can be found under "General Information". 

  • Reference current National Wetland Plant List (NWPL) for appropriate Supplement.

  • Sample points should be taken in suspect areas in order to demonstrate and document their upland/wetland status.  A suspect area is an area that is mapped as a wetland or an area that exhibits wetland vegetation, hydric soils, and/or wetland hydrology or a combination thereof.   Do not conclude an area is upland without documenting its upland status with a sample point.

  • Complete an adequate sampling of data points to document the wetland boundaries. Larger wetlands may require multiple sets of upland/wetland data points.

  • Use newer Soil Color Chart (Munsell currently recommends replacing Soil Color Chart every two years) to color soils.  Color chips can fade and lead to incorrect interpretation of soil.

  • Use ‘wetland delineation’ print day glo pink (or day glo orange) flagging or ‘wetland delineation’ print pin flags to identify wetland boundary.  Do not use plain flagging or plain pin flags as surveyors and utilities also use these.

  • ‘Wetland delineation’ pin flags or ‘wetland delineation’ flagging tied to wood lathe should be used when possible.

  • When it is necessary to tie/hang ‘wetland delineation’ flagging, tie it on woody vegetation or permanent structure and not on herbaceous vegetation. 

  • Wetland boundary flags should be spaced so that no waters of the US, including wetlands, are omitted between flags.

  • Delineate the Ordinary High Water Mark (OHWM) for non-wetland waters, including waterways and drainages.  Place flags for survey and field verification and document the OHWM indicators observed at all observation points.  The OHWM is not set at any hydraulic recurrence interval nor from a floodplain map, and should be observed in the field.  If wetlands exist outside of the Ordinary High Water Mark (OHWM) of a waterway or water body, flag the waterway/water body and abutting wetland as one area, do not flag them as separate areas.  

  • We strongly encourage completion of a wetland delineation course based on the 1987 Corps Wetland Delineation Manual for anyone putting their names as Investigators on data forms.   In addition, we strongly encourage anyone conducting delineation work within our boundaries to have completed training on the use of the Midwest and Northcentral and Northeast Supplements.

  • If any portions of site are actively farmed or appear to have been farmed within the last 5 years, then presence/absence of wetlands and their boundaries in farmed areas are determined using Chapter 5: Difficult Wetland Situations/Agricultural Lands of the Midwest or Northcentral and Northeastern Regional Supplement to the Corps of Engineers Delineation Manual and/or the USDA IL or IN Wetland Mapping Conventions and/or 2022 Lake County SMC REGULATORY GUIDANCE MEMORANDUM #2022-01

  • Conducting delineation work with an experienced delineator (i.e., a Professional Wetland Scientist (PWS) and/or Certified Wetland Specialist (CWS)) prior to conducting solo delineation work is strongly encouraged. 

  • When digging soil pits, we strongly recommend the use of tile spades/Sharpshooters versus the use of soil augers and/or soil probes.  Use of soil augers and/or soil probes can alter the soil profile and therefore alter soil data.

  • We strongly recommend that wetland boundary surveys are prepared by a Professional Land Surveyor (P.L.S.) in Illinois, or by a P.L.S. or P.E. in Indiana, regardless the stage of the project.

  • Delineation boundary surveys prepared by a P.L.S. (or P.E. in Indiana) need to be included with all permit applications so that impact acreages can be calculated accurately.

  • Delineation fieldwork should occur within growing season and under normal circumstances whenever possible.  Information on the growing season start times can be found in Chapter 4 of the Supplement to Delineation Manual: Midwest Region.  However, Project Managers have the discretion to accept delineations completed outside the growing season on a case-by-case basis.  

  • Delineations performed at the beginning or end of the growing season may not be an adequate representation of vegetative diversity. Therefore, the Corps may require additional vegetative surveys.



  • Include description of general site conditions as well as descriptions for each delineated area. This should include acreage and/or square feet for all delineated areas and wetland community types (i.e., emergent, forested, etc.) for each delineated area. If areas were delineated using OHWM you will need to include information on delineated waterways including width, length, flow duration (i.e., perennial, intermittent, ephemeral), flow direction, and condition.

  • Reports should, at minimum, contain the following figures that clearly depict property boundary or limits of project area: general location map, US Geological Survey (USGS) Topographic Map, National Wetlands Inventory (NWI), soils map generated using USDA-NRCS’s Web Soil Survey website, recent (representative of current land use) aerial photograph showing locations of sample points, and delineation figure (if areas were delineated) consisting of aerial photograph with delineation boundary overlay and/or Plat of Topography/Topographic Map with delineation boundary overlay.

  • Show road names and portions of adjacent lands on all report figures and exhibits.

  • Provide latitude/longitude in decimal degrees for each delineated area.

  • Describe observations of OHWM at multiple points in written format.

  • Provide GIS shapefiles for each delineated area if available.

  • If the project you are working on will require a permit, you should complete a plant inventory for wetland and upland portions of site and generate an Inventory for each using the Inventory Calculator found in the Chicago Region Floristic Quality Calculator, and also compile a wildlife list for purposes of fulfilling Section 7 of the Endangered Species Act (ESA).  To complete a rigorous plant inventory, complete a meander survey to assess vegetation throughout the wetland, and capture multiple data points.

  • Farmed wetland determinations need to be completed for all sites that have land in agricultural production (or that have been actively farmed within the last 5 years). The process for assessing the presence of wetlands on agricultural land is detailed in Chapter 5 of the Supplement to Delineation Manual: Midwest Region.  Please note that in these situations the farmed wetland determination method must be used to determine the wetland boundaries. Conventional wetland delineation methods are not permissible in these situations.


Following these standards will help to expedite our review of delineation work.   Flexibility of these standards may be determined by the District on a case-by-case basis only.  Please remember the Corps has the ability to reject delineation work that is: incomplete, inaccurate and/or conducted outside of the growing season.  


POC:  Mr. Andrew Blackburn, PWS, CWS or Telephone: (312) 846-5543