HI HB99

Amends Hawaii's underground injection control program to require a National Pollutant Discharge Elimination System (NPDES) permit for all underground injection starting January 1, 2031.

Prohibits underground injection without an NPDES permit after the January 1, 2031 deadline, addressing impacts identified in the 2020 Supreme Court case County of Maui v. Hawaii Wildlife Fund regarding wastewater discharge via injection wells.

Maintains existing restrictions that the director cannot issue permits for sewage wastewater injection wells unless alternative disposal options are not available, feasible, or practical.

Requires injection well operators to meet standards protecting drinking water sources and comply with inspection, monitoring, recordkeeping, and reporting requirements under the underground injection control program.

Defines "injection well" as a shaft or hole deeper than it is wide where subsurface fluid disposal occurs, and "sewage wastewater" as any liquid waste including human or household sewage regardless of prior treatment.