MESA DUST REDUCTION NEWS

2025 Annual Report and Work Plan Approved by APCO

On October 16, 2025 the San Luis Obispo County Air Pollution Control Officer (APCO), Karl Tupper, approved the 2025 Annual Report and Work Plan (ARWP) submitted by California State Parks. (See all the ARWP document, click here) This was after the required public workshop during the October 15th meeting of the APCD Hearing Board. At that meeting, the APCO received comments from the Hearing Board and the public. The approved work plan includes the following: o Provide supplemental seeding and vegetation planting on 42.5 acres of previous vegetation treatment areas o Continue Dust Control Program field monitoring and air quality modeling activities o Continue SAG consultation, including updating the approach to evaluating Dust Control Program progress o Continue to implement the Dust Control Program public relations campaign o Coordinate with the California Coastal Commission on 2024 ARWP permitting requirements, if needed. The approved work plan does not include any additional areas of dust controls. State Parks asserts the law does not require them to abate particulate matter emissions to less than natural levels. In both the 2024 and 2025 ARWPs, State Parks asserted that the already installed dust control projects achieved compliance with the Stipulated Order of Abatement (SOA) particulate matter mass emissions reduction requirements. This was based on measurements of surface emissivity at numerous locations inside and outside of the off road park that were applied to a computer model estimate of the total mass emissions. This result was compared with a similar computer model estimate of the 1939 pre-disturbance mass emissions, which is taken as a measure of natural emission levels. State Parks contracted with the Desert Research Institute (DRI) to take measurements and develop the computer models from that data. The APCO stated at the October 15, 2025 Hearing Board meeting that the 2025 work plan was acceptable because the modeling showed the current area of dust controls are sufficient to meet the SOA emissions reduction goal. It would appear that this testing and modeling of dust emissions will be the ongoing means used by the APCD to assure air quality regulatory compliance. In the first draft ARWP, State Parks proposed seasonally opening 100 acres of the Plover Exclusion area to vehicle access. After the APCO objected, State Parks modified the ARWP to read as follows: In addition, State Parks has initiated preliminary planning activities to potentially reopen a portion of the Plover Exclosure to seasonal recreation activities. This planning process will include coordination with the SAG and other agencies and, once a specific plan is determined, SLOAPCD review and approval.” In response, the APCO’s final approval letter states ARWP approval is contingent on the following condition: If the Plover Exclosure area, in whole or in part, is reopened to public vehicular access, State Parks shall simultaneously implement District-approved dust controls sufficient to offset the resulting increase in emissions. If feasible, a final set of PI-SWERL measurements should be made in the area before it is reopened.”

Hearing Board Approves Modification of the SOA

At its October 15, 2024 meeting the APCD Hearing Board asked APCD staff and the Science Advisory Group (SAG) to try to develop an SOA compliance metric that is based on measured airborne particulate matter (PM10) concentrations. The SAG presented a suggested approach at the June 25,2025 Hearing Board meeting. It was based on a ratio of PM10 concentration and wind strength. At that time the results only considered PM10 measurements at the Call Fire (CDF) monitor. The Hearing Board asked SAG to refine the metric and come back to the Board with data that also includes results for the Mesa 2 and Oso Flacco monitors. SAG presented the updated metric results at the October 15, 2025 Hearing Board meeting. The refined metric showed correlation with other PM10 concentration analyses. However, the APCO and SAG voiced concern that there was enough variability in results for them to not recommend using it as an SOA compliance metric at that time. Nevertheless, there was enough interest on the part of the APCO to recommend SAG continue to refine the metric. Consequently, the Hearing Board approved the following modification to the SOA: 1. The Respondent, APCO, and Scientific Advisory Group (“SAG”) shall continue to refine the measurement-based metric (“SAG metric”) that is described in the Air Pollution Control Officer’s Application To Modify The Terms And Conditions Of Stipulated Order Of Abatement In Case 17-01 dated October 8, 2025, and report results annually to the Hearing Board. 2. Unless specifically modified by this Order, all other provisions of the Original Stipulated Order and all other Orders to modify the Existing Stipulated Order Of Abatement shall remain in full force and effect. 3. To the extent the terms of the Original Stipulated Order of Abatement or any modification thereafter conflict with the terms modified by this Order, the terms modified by this Order shall take precedence. 4. Said report shall additionally include data collected by the Northern Foredune Restoration Monitor over the last year. (To see the SOA documents referenced above, click here. )