What is CHIA?
A Cumulative Hydrologic Impact Assessment (CHIA) assesses whether the mining operation has been designed to prevent material damage to the hydrologic balance outside the permit area. The Office of Surface Mining Reclamation and Enforcement (OSMRE) is required by regulation 30 CFR 780.21(g) to complete a CHIA. The CHIA is not updated at a specified interval. 30 CFR 780.21(g)(2) states "an application for permit revision shall be reviewed by the regulatory authority to determine whether a new or updated CHIA shall be required."