Every ecological desktop study for a US project starts the same way. Open USFWS ECOS. Check IPaC. Switch to the PAD-US viewer. Open the FEMA Flood Map Service Center. Load the NWI mapper. Cross-reference GBIF for species records. Copy coordinates between tabs. Manually compile everything into a report.
That process takes 45 minutes to an hour per site. For a corridor assessment with 10 points along a pipeline route, you're looking at a full day of clicking and cross-referencing before you've written a single sentence.
This guide explains every federal data source you should be checking for a US ecological desktop study, what each one provides, and how to consolidate the process.
What Is an Ecological Desktop Study?
An ecological desktop study is a preliminary review of existing environmental data for a project site. It's the foundation of every Biological Assessment, NEPA Environmental Assessment, and ESA Section 7 consultation package. The purpose is to identify known ecological constraints - designated sites, protected species, wetlands, critical habitat, and flood zones - before fieldwork begins.
A thorough desktop study saves time and money. It tells you which species surveys are actually needed, flags potential permitting issues early, and helps scope the field assessment so your biologists know what to look for when they arrive on site.
In the US, desktop studies draw from multiple federal agencies. No single portal gives you everything. That's the problem - and that's what this guide helps you solve.
The Federal Data Sources You Need
1. USFWS Critical Habitat
The US Fish and Wildlife Service maintains spatial data on designated Critical Habitat under Section 4 of the Endangered Species Act. If your project falls within or adjacent to designated Critical Habitat, Section 7 consultation is mandatory for any project with a federal nexus.
What it tells you: Whether the site overlaps with or is near Critical Habitat for any ESA-listed species. Includes species name, ESA status (Endangered or Threatened), and the geographic extent of the designation.
Where to check: USFWS ECOS Critical Habitat mapper, or the USFWS ArcGIS Feature Service for GIS users.
What to look for: Any Critical Habitat designation within your search buffer. Even if the project footprint doesn't directly overlap, proximity to Critical Habitat can trigger consultation requirements depending on the nature of the action.
2. PAD-US Protected Areas
The Protected Areas Database of the United States (PAD-US) is maintained by USGS and provides boundaries and management information for all protected areas in the country.
What it tells you: National Parks, National Wildlife Refuges, Wilderness Areas, National Forests, Bureau of Land Management lands, state parks, wildlife management areas, conservation easements, and tribal lands within your search area.
Why it matters: Development within or adjacent to federal protected areas may require consultation with the relevant land management agency. Projects near National Parks trigger NEPA review. Activities within NWRs require USFWS compatibility determinations.
Where to check: PAD-US viewer or the ESRI USA Protected Areas ArcGIS service.
3. National Wetlands Inventory (NWI)
The NWI is maintained by USFWS and maps wetland features across the United States using the Cowardin classification system.
What it tells you: Wetland type (estuarine, freshwater emergent, freshwater forested/shrub, etc.), Cowardin code (e.g. PEM1C, E2EM5P), and approximate acreage.
Why it matters: Impacts to wetlands regulated under Section 404 of the Clean Water Act require a permit from the US Army Corps of Engineers. NWI data is a screening tool - it tells you whether mapped wetlands exist near your site - but it doesn't replace a field wetland delineation.
Where to check: USFWS Wetlands Mapper at fws.gov/wetlands/data/mapper.html.
Important caveat: NWI maps don't capture all wetlands. They're based on aerial photography interpretation and may miss small, forested, or recently formed wetlands. If the NWI shows no wetlands but your site has hydric soils, ponding, or wetland vegetation, a field delineation is still warranted.
4. FEMA Flood Zones
The Federal Emergency Management Agency maintains the National Flood Hazard Layer (NFHL), which maps flood risk across the United States.
What it tells you: Whether your site falls within a Special Flood Hazard Area (SFHA). High-risk zones include A, AE, AH, AO, VE, and V. Zone X indicates moderate to low flood risk.
Why it matters: Development in SFHAs is subject to NFIP regulations and local floodplain ordinances. Flood zone data also informs habitat assessments - floodplain connectivity is ecologically significant for aquatic and semi-aquatic species.
Where to check: FEMA Flood Map Service Center at msc.fema.gov.
5. GBIF Species Occurrence Records
The Global Biodiversity Information Facility aggregates species occurrence records from museums, research institutions, citizen science platforms (especially iNaturalist), and government agencies worldwide.
What it tells you: Individual species observations with coordinates, date, data source, and licensing information. For the US, GBIF holds millions of records for federally listed and priority species including bats, eagles, sea turtles, manatees, gopher tortoises, and more.
Why it matters: Species occurrence records tell you what has actually been observed near your site. They complement Critical Habitat data - a species can be present even outside designated Critical Habitat, and vice versa.
Where to check: gbif.org/occurrence/search.
Important caveat: GBIF records vary in quality. Check the year, coordinate precision, and data source. A 2024 iNaturalist research-grade observation at precise coordinates is very different from a 1995 museum specimen record at county level.
6. State Natural Heritage Programs
Every state maintains a Natural Heritage Program (NHP) or Natural Heritage Database that tracks rare, threatened, and endangered species at the state level. These databases hold occurrence records that may not appear in federal datasets.
What it tells you: State-listed species records, element occurrences, and conservation status rankings.
Why it matters: Many states have their own endangered species laws separate from the federal ESA. State-listed species can be a constraint even if they're not federally listed.
Where to check: Each state's NHP website. Florida Fish and Wildlife Conservation Commission, California Department of Fish and Wildlife CNDDB, Texas Parks and Wildlife NDD, etc.
Important note: Most state NHP data requests require a formal application and may take 2-4 weeks. This is often the bottleneck in a desktop study timeline. Request early.
The Manual Process vs. EcoCheck
The manual process for a single site involves opening at least 5 separate portals, entering coordinates into each one, interpreting the results, and compiling everything into a coherent assessment. For a simple site it takes about 45 minutes. For a complex site near multiple designations, it can take 2 hours or more.
EcoCheck US consolidates USFWS Critical Habitat, PAD-US protected areas, NWI wetlands, FEMA flood zones, and GBIF species records into a single search. Enter coordinates or a zip code, choose your search radius, and get the complete constraints picture in seconds.
For linear infrastructure projects - pipelines, transmission lines, road widening - the Corridor Search feature lets you check multiple points along a route simultaneously, with results merged and deduplicated across all points.
EcoCheck doesn't replace a State Natural Heritage Program data request. But it gives you every federal dataset in one search, so you can scope your project, identify which state agencies to contact, and begin your Biological Assessment with the federal baseline already compiled.
What Goes Into the Desktop Study Report
A well-structured desktop study report for a US project should include:
Site description and search parameters - coordinates, search buffer radius, date of data access, data sources consulted.
Designated sites within the search buffer - Critical Habitat, National Parks, NWRs, Wilderness Areas, state parks, WMAs, and any other protected areas with their management type and acreage.
Wetland and habitat data - NWI mapped wetlands with Cowardin codes and acreage. Note whether a field delineation is recommended.
Protected species records - species name, number of records, year range, data source, and data freshness. Flag any ESA-listed species with their listing status (Endangered, Threatened, Candidate).
Flood zone data - FEMA flood zone designations and whether the site falls within an SFHA.
Survey recommendations - based on the species and habitats identified, what field surveys are recommended? Include survey type, optimal timing, permit requirements, and applicable legislation.
Applicable legislation - ESA, BGEPA, MBTA, CWA Section 404, NEPA, MMPA, and any relevant state laws triggered by the findings.
Limitations - what the desktop study can and cannot confirm. Desktop data cannot establish presence or absence of species on site. Field surveys are required for that.
Start Every Project Here
Whether you're scoping a NEPA Environmental Assessment, preparing a Biological Assessment for Section 7, or screening a site for a private developer, the desktop study is where it all begins. Getting it right up front saves weeks of fieldwork and avoids costly surprises during permitting.
EcoCheck US lets you run the federal data component of your desktop study in seconds instead of hours. Try it free for 3 days.
Patrick O'Connor is a Freelance Ecologist at Kinterra Consulting and the developer of EcoCheck US - an instant ecological desktop assessment tool for any US location. Try it free at ecocheckus.com.