The State Water Resources Control Boards agricultural expert panel continued deliberations on whether California should adopt crop-specific nitrogen limits or instead use place-based accounting to protect groundwater from nitrate contamination. Chair Daniel Geisler opened the session by outlining the days plan to continue Question 1 and assign drafting teams for the final report.

Panelists repeatedly argued that crop-specific numbers are impractical for much of Californias diverse agriculture. Thomas Arter, a panelist, said a single crop-based limit "doesn't really make sense in this context" and urged a field- or farm-based approach measured on a per-year basis, potentially using a rolling three-year average. Several panel members proposed minimum accounting units in the 40- to 160-acre range as reasonable spatial scales for assessing groundwater risk.

The panel discussed the a-minus-r metric (applied nitrogen minus removed nitrogen) as a practical accounting framework. Daniel Geisler and others framed the role of the panel as assessing whether the science supports creating targets or limits and how to get there, rather than prescribing a single numeric limit. Panelists asked for flexibility in terminology ("targets" vs. "limits") and for region-specific implementation pathways acknowledging different cropping systems and soils.

Technical evidence and management strategies were a central part of the discussion. Eric Morgan of the Soil Health Lab described a soil nitrate testing protocol used with commercial growers and reported cases where growers produced cool-season vegetables with low applied nitrogen by relying on soil supply and other practices. Morgan said growers were "making crops on 20 units of applied nitrogen" in some cases and emphasized that "a healthy soil can provide nitrogen for crops," calling regenerative practices and cover crops "the only way that a grower can actually meet the milestones" under tighter nitrogen goals.

Panelists debated how to account for residual soil nitrate (the soil nitrate test): some recommended including it for agronomic fertilizer decisions (so growers use soil supply when planning applications) but urged caution about treating all residual nitrate as "applied" for regulatory a-minus-r accounting, because residue mineralization and recycling across seasons complicate mass-balance calculations. Several speakers also stressed the importance of irrigation water nitrate (which Morgan said is "a 100%" addition to applied N when it is present) and that regionally different water sources and rainfall patterns affect leaching risk.

Modeling and reporting tools drew interest as a bridge between grower reporting and groundwater impact assessment. Panelists noted that simple farm-level a-minus-r accounting can be supplemented by process-based tools such as CV-SWAT (a Central Valley modeling approach) or other regional models that incorporate soil texture, hydrology and management to estimate leaching. Thomas Arter asked staff to arrange a comparative presentation of the Central Coast and Central Valley approaches (including CV-SWAT) so the panel could compare how different tools translate grower reports into estimates of groundwater risk.

Across regions, the group emphasized education, outreach, and incentives as necessary complements to numeric targets. Panelists urged investments in soil testing, cover-cropping incentives, and commercially viable monitoring or decision-support technologies to enable growers to reduce applied nitrogen without compromising yield. Several panelists proposed peer-based or phased approaches, where underperforming operations are given technical assistance and time-bound improvement expectations.

Procedurally, the panel formed two-person drafting teams to prepare sections of the final report and asked staff to circulate a proposed schedule: the State Water Board staff requested a draft in December if possible but offered the option of using the January 14 meeting as a draft-review workshop and adding another meeting if needed. Annalisa Tihara (State Board staff) confirmed the panels draft would be posted for a minimum 30-day public comment period before finalization.

The meeting closed after brief public comments from Gabriel Ludwig (Almond Board of California) and Tian Tran (Community Water Center), who urged the panel to emphasize groundwater-focused modeling and to set interim targets for large dischargers. Panel members asked staff to return Oct. 31 with a prioritized list of presenters (including CV-SWAT) and with the proposed meeting and document timeline so the panel can finalize drafting assignments and public outreach plans.

The panel did not adopt numeric limits at this meeting; participants agreed on the following next steps: prioritize region-specific modeling and data needs, promote soil nitrate testing and regenerative practices as part of pathways to lower a-minus-r outcomes, and circulate a draft timeline and presenter schedule on Oct. 31 so drafting teams can prepare report text for review.