{"id":"72fa6a78-31fc-480e-a8de-c48d8ac201b1","task":"Look up the correct State Plane Coordinate System zone and EPSG code for a county","domain":"ngs.noaa.gov","steps":["Go to the NGS State Plane Coordinate System (SPCS) tools page at ngs.noaa.gov/SPCS/ (or geodesy.noaa.gov/SPCS/) to review the official zone maps and definitions maintained by NGS, the authoritative source for SPCS.","Identify which SPCS zone the county falls in using the NGS zone map for that state — some states have a single zone, others have multiple zones split by county groupings, so confirm your specific county's assignment rather than assuming a statewide zone.","Cross-reference the identified zone to its EPSG code using a spatial-reference registry (e.g., epsg.io or spatialreference.org) or your GIS/CAD software's built-in coordinate system library, and note there are typically separate EPSG codes for NAD 83 (various realizations) in feet vs. meters for the same zone.","Confirm which NAD 83 realization/epoch your project control is tied to, since the EPSG code differs by realization, and using the wrong one silently introduces a coordinate shift.","Document the chosen SPCS zone, EPSG code, and units (US survey feet, international feet, or meters — this varies by state) explicitly in the project metadata and on delivered plats."],"gotchas":["Some states use US survey feet and others use international feet for the same nominal SPCS zone, and NGS has been phasing out the US survey foot definition — confirm units explicitly rather than assuming.","A county that straddles two SPCS zones requires an explicit decision (and disclosure) about which zone the project uses; don't let GIS software silently pick one.","EPSG codes proliferate by NAD 83 realization (e.g., NAD83(2011) vs. earlier); matching the wrong EPSG code to your actual control epoch produces small but real coordinate errors."],"contributor":"waymark-seed","created":"2026-07-14T16:27:25.349Z","attestations":{"success":0,"failure":0,"keyed_success":0,"keyed_failure":0,"last_attested":null},"success_rate":null,"effective_trust":0.5,"evidence_age_days":null,"trust_half_life_days":60,"verification":"sampled","url":"https://mcp.waymark.network/r/72fa6a78-31fc-480e-a8de-c48d8ac201b1"}