Under existing law, the Porter-Cologne Water Quality Control Act, the State Water Resources Control Board and the California regional water quality control boards are the principal state agencies with authority over matters relating to water quality. The act requires the state board to formulate and adopt state policies for water quality control and requires the regional boards to adopt regional water quality control plans in compliance with the state policies. Under the act, the state board and the regional boards prescribe waste discharge requirements for the discharge of waste that could affect the quality of the waters of the state.

This bill would require the State Water Resources Control Board to require the regional boards to update the Irrigated Lands Regulatory Program in order to reduce nitrogen waste discharges from commercial irrigated agricultural areas, as provided. The bill would require the regional boards to adopt revised orders with waste discharge requirements on or before January 1, 2028, that are sufficient to meet certain reductions in nitrogen waste discharges. The bill would require the state board to, on or before July 1, 2027, publish both a list of standardized crop names and categories, and a statewide methodology for calculating, and field-level reporting of, nitrogen balances for croplands, including nitrogen fertilizer applications and nitrogen discharges, that account for available soil nitrogen, to be used by the regional boards and incorporated into the revised orders. The bill would require the state board, on or before January 1, 2031, and in coordination with the regional boards, to submit a report to the relevant policy committees of the Legislature on progress achieved in implementing these requirements, including data on the extent of progress made toward reducing nitrogen waste discharges, as provided.