US lawIllinoisRegulationsTitle 35 — ENVIRONMENTAL PROTECTIONCHAPTER I: POLLUTION CONTROL BOARDSUBCHAPTER a: PERMITS AND GENERAL PROVISIONSPart 204 — PREVENTION OF SIGNIFICANT DETERIORATIONSubpart B204.48035 Ill. Adm. Code 204.480Low TerrainYear: 2026Length: 13 wordsOfficial source Section 204.480 Low Terrain "Low terrain" means any area other than high terrain.Previous35 Ill. Adm. Code 204.470Next35 Ill. Adm. Code 204.490