Coronavirus shutdown shows dust on the Nipomo Mesa science is flawed

May 25, 2020

A view of the Nipomo Mesa from the Oceano Dunes State Vehicular Recreation Area


Excessive dust days have more than doubled since RVs and off-road vehicles were barred from the Oceano Dunes, data from two Nipomo Mesa air quality monitoring sites show. California State Parks closed the Oceano Dunes State Vehicular Recreation Area to all off-road and recreational vehicles on March 28 because of the coronavirus pandemic.

The air quality data called into question the San Luis Obispo County Air Pollution Control District’s theory, disputed by California state scientists, that off-road riding activities cause high dust levels detected on the Nipomo Mesa. This theory generally ignores that the Oceano Dunes lies within a larger complex of coastal sand dunes created by wind blowing sand from the shoreline.

For years, the APCD and Nipomo Mesa residents have clashed with state parks and off-road vehicle riders over the cause of dust in the air at the Nipomo Mesa. Both sides agree strong westerly winds blowing over the sand dunes transport dust to the mesa.

In 2018, California State Parks entered into a stipulated order of abatement with the APCD. The agreement mandates that the state reduce wind-blown dust, specifically dust particles that are 10 microns or less in diameter, on the Nipomo Mesa by 50 percent. Despite agreeing to the various terms in the agreement, state parks still denies that off-roading causes the dust on the mesa.

Access denied: Approximately 50 acres of camping and beach area closed off for APCD dust projects.

The  primary goal of the agreement is to ensure that concentrations of dust measured on the mesa stay within federal and state standards, as measured at two of the APCD’s air monitoring sites on the mesa, which are known as “CDF – Arroyo Grande” and “Nipomo-Guadalupe Road.”

Overall, the state has spent approximately $14 million in tax payer revenue in the last 10 years to reduce dust concentrations on the mesa. The state covered more than 150 acres of dune sand with vegetation or orange plastic fencing. Additional dune-covering projects are anticipated in the coming months and years, under the theory that the obstructions would help reduce dust produced by the blowing sand.

In January, State Parks Director Lisa Mangat shut down approximately half of the camping area and about 5 percent of the riding area at the Oceano Dunes, or approximately 50 acres near the shoreline. The area was popular with campers, and provided 50 percent of the park’s camping availability.

CalCoastNews examined archived data from wind and dust measurements collected from the two Nipomo Mesa air quality monitoring sites to determine if State Parks’ mandated efforts along with the closure of the park in March would lead to a reduction in dust concentrations.

Specifically, reporters examined the number of daily exceedances of state and federal air quality standards during the month of May for the past six years at the two monitoring sites. The CDF site is approximately 2.5 miles from the dune shoreline, on the southwest edge of Nipomo Mesa. The Nipomo-Guadalupe Road site is about four miles from the shore, on the lower edge of the mesa. Agricultural lands lie between the coastal dunes and the Nipomo Mesa.

The parameters were chosen because May is typically the windiest month in south San Luis Obispo County, and 2015 predates the various dune-covering operations undertaken by State Parks.

Wind data indicates that May’s average wind speed at the two monitoring sites has varied little from year to year. At the CDF site, the May winds average at about 5 miles per hour, and at the Nipomo-Guadalupe Road site, the winds are slightly stronger, averaging about 5.5 miles per hour.

The number of exceedances of California’s air quality standard for airborne dust tells a different story. At both of the air monitoring stations, a substantially greater number of May exceedances occurred this year compared to the other years, even though there have been no recreational vehicles on the dunes; and the month of May has not yet ended.

For example, at the CDF site in May 2019, there were six exceedances, but this year, as of May 22, the exceedances have doubled to 12. At the Nipomo-Guadalupe Road site in May 2019, there were only three exceedances, but as of May 22, exceedances have nearly quadrupled to 11.

As part of the agreement, a panel of scientific advisors, known as the Scientific Advisory Group (SAG), was formed to assist in the design and implementation of the various dune-covering projects. The SAG is led by William Nickling, an emeritus professor at the University of Guelph in Ontario, Canada.

In apparent anticipation that continued high-dust days with no vehicle recreation in the dunes would cause confusion, on April 6, Dr. Nickling and other SAG members authored a memorandum regarding the vehicle closure at Oceano Dunes and possible changes in dune dust emissions.

“It is the opinion of the SAG that the accumulated impact of OHV [off highway vehicle] activity remains a significant contributor to observed PM [dust] emissions at ODSVRA, even during this period in which the ODSVRA is temporarily closed to recreational uses,” according to the memorandum. “The SAG acknowledges that the Oceano Dunes are a naturally dusty surface that would experience PM emissions even in the absence of human activity, especially during this spring windy season. But the SAG is also clearly aware that decades of OHV activity have fundamentally altered the natural beach-dune landscape, making the dunes significantly more susceptible to PM emissions than they would be in a natural state.”

However, the SAG memorandum fails to explain how the dunes have been “fundamentally altered” to emit more dust, and also why the SAG did not anticipate the number of state exceedances for dust to substantially increase in the absence of vehicle recreation on the dunes.

One theory is that the recreational vehicles that used to park on the dunes, helped obstruct the wind flow.

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Jorge Estrada

in my opinion the important thing here is the issue, just fund it and keep the meetings ongoing. Eventually someone will retire and then there will be another issue.


The APCD is having a meeting today at 9. This issue has been used by several politicians selected by Adam Hill to attempt to take the District 4 supervisor seat. Jimmy Paulding was Adam Hill’s latest, and he is on the APCD Board. Jimmy Paulding is smart, he knows the science is bunk, but he played the people who live on the mesa, claiming the dust was making them sick and he could help them. Will he double down today, and vote with Adam Hill? Or will he admit the science is bunk, and focus on what is best for the community and real solutions? Everything Paulding does is with an eye on moving up politically, but with Adam Hill under an FBI investigation, what is best politically? This should be an entertaining meeting to watch.


It is a dangerous game when politicians terrorize the elderly with false stories of lethal health threats in order to secure their votes and funding, thereby stopping them from finding real solutions that protect their wellbeing.


Very interesting…this virus has exposed a lot of myths on the environment…..fear does refocus ones attention….doesn’t it?…


This started when the APCD knew they were losing their revenue stream from the Morro Bay power plant. It was clear from the start, that this theory was not based on science, but on greed. Now the state is spending a million a year on mitigation and another approximately $200,000 to the APCD to monitor the dunes.

It is time to shutter the APCD or move it back to the county. Lay off half of the overpaid employees and reduce pay on the rest.

With Covid-19, the taxpayers do not need to lose a revenue stream by closing half the dunes and then pay a million a year for fake science, all so the APCD can continue giving themselves fat raises.

Adam Hill and Bruce Gibson played along, aware it was fake science, and used it to say anyone who questioned the APCD did not care about the health of those who live on the Mesa. All the while, the people who live on the Mesa were not looking for legitimate ways to stop the dust.


The people lose coming and going. They lose a huge economic engine that generates taxes, and they lose doubly when what is left of tax revenues goes to fund one government agency’s legal battle against another government agency. There’s more, but this alone shows the absurdity of this politically fabricated scam.


Scientist and experts continue to spew whats best for us. Don’t dare dispute or question them. However when they are proven wrong the people suffer the consequences and they go on their merry way. Reopen ALL of the dunes now.


And the SLOAPCD somehow removed 50% of the park’s prime camping? For dust on the Mesa? And there is nothing to show for it? Are they unaware that Oceano Dunes brings major $$$ into a part of the county that desperately needs $$$? That’s always been important, but especially now, with the closing of Diablo Canyon and the economic impacts from the coronavirus. The SLOAPCD is out to lunch, as are the new nymby’s of the Mesa—those relocated LA- and SF-area retirees living in the Trilogy development. I guess since they are retired they don’t care much about the economics of the south SLO County community they invaded.


Even more out to lunch are the numbskulls we elected who sit on the APCD board. Vote them out next election…Karen Bright, Mariam Shah, Beuce Gibson, Adam Hill, John Hamon, Ed Waage, Arroyo Grande and Morro Bay Representatives…there are others.


Did I read this right?! “The state has spent approximately $14 million in tax payer revenue in the last 10 years to reduce dust concentrations on the mesa“? More than a million bucks per year? And now we know it has been for nothing? WTH???


Downy, there’s a typo at the end of your post. You accidentally pressed the “H” key instead of the “F” key.


In 2018, California State Parks entered into a stipulated order of abatement with the APCD. The agreement mandates that the state reduce wind-blown dust, specifically dust particles that are 10 microns or less in diameter, on the Nipomo Mesa by 50 percent.

Why not just mandate that the wind stop blowing and the sand not be present on the beach? Seems that would solve the problem!

(hope I’m not giving them any serious ideas)



That’s the first thing I thought too: why not just write some tough legislation that stops the wind from blowing? Great idea, but how to enforce? Also, what if it turns out that some wind is good? Also, it’s tough to control the wind over a small area, like the Dunes….it could mean that the wind isn’t blowing enough on Teft Street and that could result in higher energy costs…..

We’re just not there yet….shutting off the wind. But it’s a great idea.

The only way to save the Dunes is to shut them off from the public forever.

Shoot, when you study the “science” pretty soon you realize that the only way to save the planet is to kill a bunch of people. That’s not a popular truth….and I get that.

I guess as long as I’m essential….

Last Individual

Great idea Doc. Let’s stop the wind. We could put up enough wind generators to absorb all the wind energy. We could make the blades out of something that needs to be sand blasted. Also the force of the wind on the structures would make the earth spin faster. This would make days shorter reducing the time to measure particulate each day. It would also reduce our wind tax that Nuisance is set to unveil any day. The benefits are endless. Does anyone know a Canadian doctor to work out the details.


Is it just me or did this “doctor” just double down on stupid?