CA SB601

Establishes "nexus waters" as a new category of state-regulated waters, defined as all waters of the state that are not federally navigable waters, with specific exclusions for groundwater, waste treatment systems, prior converted cropland, and certain artificial water bodies

Requires waste discharge requirements for point source discharges to nexus waters to comply with Federal Water Pollution Control Act standards, treating nexus waters as though they are navigable waters of the United States for regulatory purposes

Mandates that water quality standards that applied to nexus waters as of May 24, 2023, remain in effect, and requires state and regional boards to include nexus waters in Clean Water Act processes including the California Integrated Report and total maximum daily load establishment

Creates annual inflation adjustments for civil monetary penalties beginning January 1, 2026, with increases capped at 150% per year and proceeds deposited into a new Penalty Adjustment Account for water pollution cleanup

Authorizes the Attorney General, state board, regional boards, district attorneys, county counsels, and city attorneys to bring enforcement actions for violations related to nexus waters, with civil penalties up to $75,000 per day per violation