Will data spur change in dust mitigation on the Oceano Dunes?
June 4, 2022
Oceano Dunes dust mitigation fencing
By KAREN VELIE
After installing more than 230 acres of dust mitigation measures within the 1,000-acre off-highway vehicle riding area at the Oceano Dunes, the number of violations for exceeding the state’s pollution standard on the Nipomo Mesa in May 2022 was the highest in eight years, which further refutes the argument that vehicles on the dunes are the cause of pollution on the mesa.
For more than a decade, the San Luis Obispo County Air Pollution Control District (APCD) and Nipomo Mesa residents have clashed with State Parks and off-road vehicle enthusiasts over the cause of particulate pollution in the air at the Nipomo Mesa. The APCD has claimed that on windy days, the pollution is almost entirely due to mineral dust particles blowing from the Oceano Dunes State Vehicular Recreation Area, which is located more than two miles from the mesa.
State Parks entered into a stipulated order of abatement with the APCD in 2018. Among other things, the order requires State Parks to reduce the number of violations of the state’s particulate pollution standard on the Nipomo Mesa by 50%. These violations typically occur in the spring months, particularly in May, when strong on-shore prevailing winds blow in south San Luis Obispo County.
Under the APCD’s order, State Parks began closing large portions of the vehicle riding area and installing fencing and vegetation in an effort to reduce the amount of mineral dust blowing from the park’s dunes. More than 230 acres have been covered thus far.
The APCD has claimed these measures have been successful at meeting the violation-reduction metric of their order. However, this past May the number of violation days has increased to its highest level in eight years despite the mitigation efforts.
Violations of the state’s particulate pollution standard during the month of May, from 2015 through 2022:
- 2015 – 5 violations
- 2016 – 4 violations
- 2017 – 10 violations
- 2018 – 9 violations
- 2019 – 6 violations
- 2020 – 12 violations
- 2021 – 7 violations
- 2022 – 16 violations
While the APCD claims that the particulate pollution on the Nipomo Mesa is almost entirely mineral dust, the Scripps Institution of Oceanography analyzed the particulate and determined that at most only 14% of what the APCD measures on the mesa consists of mineral dust.
Scientists refer to the process of dust emissions from the dunes as saltation, which is a “natural dune building process that causes sand and finer material to be pushed and bounced downwind.” The saltation process generates mineral dust.
In its attempt to appease the APCD, State Parks has spent more than $22 million (page 5 of report) to stop saltation in the dunes by planting vegetation and installing fencing.
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