Connecticut in 3D: What Statewide Lidar Is Worth to the State

Connecticut is small, dense and largely wooded: hills and low mountains in the Western Upland, hills in the Eastern Upland, ridges and broad valleys in the Central Lowland, and beaches and harbours along Long Island Sound. About 60% of its people live near the coast, where storms and rising water reach them first. Much of what the state and its towns do — issuing permits, managing resources and infrastructure, engineering and planning — depends on an accurate 3D model of the land, which comes from lidar (laser scanning from aircraft).

The national program

The 3D Elevation Program (3DEP), run by the U.S. Geological Survey with federal, state, tribal, territorial and local partners, is building consistent lidar coverage of the whole country at quality level 2 or better, with elevation models of 1 meter or finer that meet the USGS Lidar Base Specification.

Connecticut's coverage

In 2015 the Capitol Region Council of Governments, on behalf of all nine of the state's regional councils, won a grant from the Office of Policy and Management's Regional Performance Incentive Program for statewide lidar, with more funding from the state's Transportation and Emergency Services departments. Connecticut received complete QL2 coverage in 2017 — its 3DEP baseline is 100% complete. Since then the state has collected statewide 3-inch aerial imagery (delivered spring 2023) and QL1 lidar at 20 points per square meter on the coast and 15 elsewhere (expected in 2026).

3DEP baseline lidar in Connecticut, as of July 2024: available or in progress statewide. USGS

What it is worth

The National Enhanced Elevation Assessment (Dewberry, 2012) estimated conservatively that the data would bring Connecticut at least $4.40 million a year in new benefits:

The coast

The Connecticut Coastal Management Act of 1980 is the core of the state's coastal program, shared between the state and its towns: it draws the coastal boundary and sets the policies and procedures. Seamless maps of upland ground, the intertidal zone and the sea floor improve coastal hazard models, the mapping of paved surfaces, resilience plans and storm response — protecting the shoreline and the tourism and fishing that depend on it.

Floods

Accurate elevation makes flood maps more accurate and cheaper to produce, and better maps mean better preparation. When the remnants of Hurricane Ida dropped heavy rain on the state in September 2021, this was the kind of event lidar lets planners model in 3D — overflowing streams, dam failures, storm surge over the coast — and QL1 data sharpens those predictions in high-risk coastal areas, for evacuation routes and public protection.

A sample of 3DEP QL2 lidar at Hartford, colored with aerial imagery, where the Connecticut River passes under Interstate 84. USGS

Land and habitat

Across a state rich in habitats, the same data help governments limit stormwater runoff, protect tidal marshes and open space, site trails, farm better, and identify and protect habitat.

Data can be found and downloaded through the USGS Lidar Explorer.

Sources

Written from The 3D Elevation Program—Supporting Connecticut's Economy, U.S. Geological Survey Fact Sheet; a work of the United States government in the public domain. It cites Dewberry (2012), Heidemann (2012), Sugarbaker and others (2014), Hoyt and others (2024), the Connecticut Department of Energy and Environmental Protection (2020) and NOAA (2012).