County staff presented highlights from a draft tree canopy assessment at the April 16 Planning Commission meeting, showing about 250,000 acres of tree canopy across rural Thurston County and mapping areas with high potential for canopy restoration and areas where forest encroachment threatens prairie soils and Oregon white oak habitat.

Claire (county staff) said the analysis uses LiDAR collected by the University of Vermont, reported at an accuracy of about 97 percent, and aggregates data into 250-acre hexagons so maps show landscape patterns rather than site-specific property lines. Staff reported three headline findings: 61 percent of the rural county is tree canopy, 68 percent of that canopy is on private land, and 48 percent of the canopy falls on land zoned for residential uses. The packet provided to commissioners includes more than 15 maps and accompanying tables and narrative still in draft form.

The assessment includes a restoration-potential map that flags hexagons with few trees and few competing land uses as higher priority for canopy restoration, and a separate map showing where prairie soils are overlain by canopy — an indicator of forest encroachment onto prairie and Oregon white oak habitats. Claire said the maps are intended to help prioritize where to plant trees and where to restore prairie open space, noting there is limited overlap between high-potential tree-restoration areas and areas where prairie soils are presently covered by trees.

Commissioners and members of the public asked how the assessment will be used in regulation and programs. Staff said the first regulatory application will likely be the periodic update of the county’s Critical Areas Ordinance (expected in 2026–27) and that the data could also inform grant applications, programmatic restoration efforts, and regulatory tools for conservation. Staff cautioned that at a 250-acre aggregation scale the maps are not a substitute for site-level biology or hydrology work; restoration planning for specific properties would require site-scale studies and qualified biologists.

Speakers highlighted the cultural and ecological importance of prairies and Oregon white oak, reminding commissioners that indigenous stewardship (for example, controlled burning) historically maintained open prairie and oak habitats. Commissioners and public commenters asked staff to include methodology details and appendices in the final report so the dataset and mapping choices are transparent when the county uses the assessment for funding or regulatory decisions.

Claire said the draft report will be finalized and made publicly available and that staff welcome feedback on additional analyses or uses for the assessment. The commission’s discussion continued into the comprehensive-plan item; staff indicated they will bring the finalized assessment materials to future hearings and to the proposed Critical Areas Ordinance update.