Agricultural expert panel urges regional flexibility for nitrogen targets, improved INMP data

A statewide agricultural expert panel convened by the State Water Resources Control Board released draft recommendations on May 14 calling for regionally tailored approaches to nitrogen limits for irrigated lands, improved data collection and iterative, science‑based interim targets.

State staff convened an eight‑member panel to answer nine technical charge questions after two orders (Eastern San Joaquin and Central Coast) directed the state board to revisit prior guidance. Panelists concluded that where sufficient data exist, regions can develop long‑term, crop‑specific nitrogen targets; where data are limited, regions should prioritize new data collection and use reasonable interim methods.

The panel supported continued use of a nitrogen mass‑balance metric (A minus R) to track potential nitrogen loading to groundwater and recommended that A/R ratio metrics be used for grower performance benchmarking rather than as direct discharge limits. It also proposed standardizing INMP summary report formats to improve data validation and urged additional research into root‑zone and hydrologic models to better account for nitrogen transformations and leaching processes.

Panelists recommended an iterative approach to interim targets — targets could be set below long‑term nitrate objectives and tightened over time as more data and modeling reduce uncertainty. They also encouraged credits for nitrogen in compost and organic fertilizers and recognition of lower‑risk operations (for example, certain container nurseries) as candidates for alternative compliance pathways, subject to further research.

Process and next steps: staff will compile public comments received on the draft recommendations and provide them to the panel (compilation delivered May 15); two working‑group meetings in late May and a final plenary on June 5 are planned to finalize recommendations. The chair will present the panel’s final recommendations to the state board in an informational item on June 16; staff will then begin a technical evaluation and propose implementation options.

Why it matters: The panel’s guidance aims to bridge scientific uncertainty and regulatory needs by directing limited monitoring resources to regions and crops where they will most improve decisionmaking, while offering pathways to implement interim protections where groundwater is at risk.

What remains unresolved: How to sequence new data collection across diverse regions, the timing and legal pathway to adopt statewide policy versus regional orders, and the resource needs for scaling monitoring and modeling.