But yes, the beach was "contaminated" with naturally occurring thorium and radium.
From Half Moon Bay Review (1/8/2014):
Experts say beach radiation unrelated to Fukushima
...The amateur video went viral, drawing more than half a million views to date, and spurring government inspectors to conduct their own surveys.
After watching the clip, El Granada electrical engineer Steven Weiss grabbed his own radiation measurement equipment to test the radiation reports for himself.
On Monday, Weiss carried a Geiger counter in each hand for a second survey of Surfer's Beach. As he descended to the waterline, the readings on his gadgets climbed. He tested various spots: the side of the bluffs and the white sand closest to the waterline, both registering levels that were high but not suspiciously so as far as he was concerned. But when he placed the sensors down near a line of black silt along the back of the beach, the meters on both his gadgets spiked. The counters registered about 415 counts per minute. A cpm of 30 is considered the baseline for radioactivity typically found in the air.
“It's not normal. I've never seen 400 cpm when I just wave my Geiger around.” he said. “There has to be something radioactive for it to do that.”
Weiss is no amateur; for 40 years he has made a living designing Geiger counters, most recently for International Medcom Inc. After he verified the hotspot, he took a sample of the dark sediment and sent it to his company's main offices in Sebastopol for analysis.
International Medcom CEO Dan Sythe later put the dirt sample in a spectrum analyzer to view the radioactive “signature” of the particles, the photon energy associated with each isotope. What he found was different from cesium-137, the fissile material used in the Fukushima reactors. He would know – since the 2011 meltdown, Sythe has visited Japan nine times to help map the cesium fallout.
Instead he was seeing radium and thorium, naturally occurring radioactive elements.
Nonetheless, the presence and concentration of natural thorium and radium at Surfer’s Beach left experts puzzled. Both elements are actually common at beaches. In fact, a 2008 study by the Journal of the Serbian Chemical Society found similar concentrations at Southern California beaches.
Sythe offered a couple possible explanations. A vein of thorium could be spilling out from the nearby coastal bluffs, he suggested. Alternatively, he heard mention of an old oil pipe running nearby the beach. Oil pipelines had a tendency to collect heavy radioactive minerals, he said.
Peterson thought the minerals could be just washing up with the salt water from the shores. The radioactive materials all were just past the high tide line, so it made sense that would be where the minerals would build up, he said.
“The conditions that are out on the beach could be the same conditions that have been out there for millennia,” he said.
Update: Tests by government health inspectors have found no connection between the elevated radiation levels at Coastside beaches and the Fukushima Daiichi disaster, according to a statement by the California Public Health Department released late on Tuesday evening. An analysis by county and state officials found the radiation was the result of naturally occurring minerals, a conclusion similar to reports by independent experts.
(Full article at the link)
But the net media who went there to prove the source of radiation was the wrecked nuclear plant halfway across the globe is undeterred:
...Working to relieve concerns that the high radiation readings indicated fallout from Japan’s Fukushima Daiichi nuclear power plant had finally reached the United States, electrical engineer Steve Weiss, a radiological expert who has worked on Geiger counters for 40 years, examined the same beach as the man in the video, and presented even worse results.
Weiss found levels well in excess of 1,400% of what acceptable amounts should be.
“It’s not normal. I’ve never seen 400 cpm when I just wave my Geiger around,” Weiss told the Review. “There has to be something radioactive for it to do that.”
After a spectrum analysis of the dirt on the cove, the paper later discovered the isotopes to be naturally occurring thorium and radium, and not cesium-137, the fissile material employed at the Fukushima reactor. This led many to scrap the notion that radiation from the damaged nuclear plant in Japan was the cause of the high readings. We, however, were not convinced, and set out on a mission to conduct radiation measurements up and down the coast.
And on they went, armed with a pocket geiger counter ("Inspector" brand, it looks).
Unless you find cesium-134 in addition to cesium-137, you can't tell whether cesium-137 is from Fukushima or from the atmospheric nuclear testing that the US has done so many times. And without analysis by a gamma-ray spectrometer to see the distinct peaks for nuclides and knowledge to read them, well...