State GIS director tells House committee statewide LiDAR, parcel and imagery programs support flood, land-use and municipal work

John Adams, director of the Center for Geographic Information at the Agency of Digital Services, told the House Agriculture Committee that the state’s geographic information system (GIS) program maintains foundational datasets — including imagery, elevation (LiDAR), parcels and land cover — and makes them available through a single GeoData portal.

Adams said the program “build[s] the foundational datasets” and that the portal is widely used: “In 2024, we had, really an astounding number of users. We have around 250,000, unique users.”

Why it matters: the datasets Adams described are used for flood modeling, parcel management, emergency response and other planning tasks that state and local agencies rely on. Adams demonstrated tools that let users view buffers around designated areas, inspect parcel ownership and export parcel tables for analysis.

Adams described recent technical upgrades and key program facts. The agency now uses high-resolution airborne LiDAR and processed point clouds to create bare-earth elevation models and extract features such as tree height and stream lines. “We’ve got around a trillion points measurements,” he said, describing the raw LiDAR return data. He said LiDAR quality has improved from coarse 30-meter data in 2010 to a 0.35-meter resolution product produced in a statewide flight in 2023.

Adams showed an example of using LiDAR and orthophotography together to refine floodplain mapping and to map landslide damage in Waterbury. He said University of Vermont researchers use machine learning with the state data to derive land cover and extract building and vegetation footprints that improve E911 and other spatial datasets.

On parcels, Adams said the statewide parcel program produced a near-complete base layer in cooperation with VTrans and other agencies. He gave these figures during the presentation: about 340,000 parcels in the statewide parcel dataset, roughly 2.2% unmatched parcels, a parcel viewer accessed “over a million times” in the past year and a land survey library with roughly 2,200–2,500 surveys available. He also said the tax department’s property-transfer data are now mapped back to 2019 and are updated weekly in the system.

Adams emphasized that the parcel program is voluntary for municipalities. “For a voluntary program, it is fairly successful,” he said, noting about 90% of towns maintain parcel data and many towns supply updates on varying schedules. He said seven agencies including the Agency of Transportation helped fund the initial statewide mapping up to 2020, and updates are currently voluntary.

Committee members asked about specific uses and limits of the data. Adams cautioned that while the system can report parcel counts and total parcel acreage inside a buffer, the tax department’s data only supply parcel enrollment identifiers (SPANs) and not the precise acreage portion enrolled in current-use for each parcel. “We can tell you the entire size of the entire parcel, but that doesn't necessarily tell you how much of it is enrolled in current use or not,” he said.

Adams offered staff assistance to the legislature and public: “Everything that we have is public and available online…if there's something that you can access or are interested in, don't hesitate to reach out and we will get it to you if it exists.”

Adams also described a tree-level plan enabled by the higher-resolution LiDAR, saying a forthcoming product will effectively “have every tree” with height information, though it will not identify species. He noted research partnerships with UVM and pilot work with the USGS to derive LiDAR-based stream and river lines.

The committee did not take a vote on any action during the presentation. Adams closed by reiterating that most datasets and the viewers are publicly available and that staff will support reasonable requests from legislators and state agencies.