Subject: Update on Hamilton County, Indiana's 3DEP & 3DHP-Aligned Data Modernization
Hi everyone,
I want to share a brief clarification and update following my recent post about Hamilton County's new lidar and Elevation-Derived Hydrography (EDH) work. Several colleagues reached out with questions, and I thought it would be helpful to provide a bit more context for the full group.
Hamilton County's 2024 QL1 lidar and EDH development were part of the County's internal basemap, lidar, and hydrology modernization effort. These datasets directly support local integration with our stormwater systems, regulated drains, and wetlands mapping. While the work follows the 3DEP and 3DHP technical specifications, it was completed on a local timeline to meet immediate operational needs-not as DCA acquisition projects with USGS.
To ensure future alignment with national programs, the County has submitted coordinated FY25 3DEP and FY26 3DHP DCA proposals.
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The FY25 award supports USGS validation of the County-funded QL1 lidar for use as updated 3DEP elevation data.
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The FY26 proposal builds on that foundation and includes formal guarantees for EDH corrections by our contractor (Dewberry) so the hydrography will fully align with the final validated DEM and the 3DHP EDH specifications when USGS is able to review it.
Hamilton County remains committed to sharing our new elevation and hydrography data with state and federal partners and ensuring they can both support Indiana's statewide 3DHP planning and future national integration through the 3DEP and 3DHP programs.
Thanks to everyone who has reached out with questions-happy to continue the discussion as more counties and states begin exploring similar workflows.
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Philip Worrall
Retired
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Original Message:
Sent: 11-21-2025 17:01
From: Philip Worrall
Subject: Results of Hamilton County, Indiana's 3D Hydrography EDH Data Development:
Since my "second retirement from NSGIC" last year, I've continued to work with the Hamilton County, Indiana GIS Department (the county where I live) on the first county-level 3D Hydrography Program (3DHP) Elevation-Derived Hydrography (EDH) project in our state-and I wanted to share our results with you.
This work was completed as part of Hamilton County's 2024 Basemap Update Project and was fully aligned with both the USGS 3DEP and 3DHP programs and the County's hydrography mapping requirements. For the 3DHP component, Dewberry Engineers produced EDH from the county's new QL1 3DEP lidar and prepared it for contribution to the USGS national 3DHP database. To meet our county requirements, they also integrated the new EDH data with our local government storm sewer networks, regulated drains, and developed new AI/ML-based wetlands predictive modeling/mapping layers. When the project wraps up next month, the county will also share these datasets with the Indiana Geographic Information Council (IGIC) Waters Workgroup and the Indiana Geographic Information Office (IGIO) to help inform their development of a statewide 3DHP plan.
Earlier this week Hamilton County hosted a 3DHP – EDH 101 technical workshop for local and state partners who will begin seeing and using this new data next month on the County's GeoHUB. Presentation materials are available below:
I'm very excited about our results and hope you find this information timely and useful!
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Philip Worrall
Retired
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