Related info:
Measurements of Fission Products from the Fukushima Daiichi Incident in San Francisco Bay Area Air Filters, Automobile Filters, Rainwater, and Food, Dec. 27, 2013: A variety of environmental media were analyzed for fallout radionuclides resulting from the Fukushima nuclear accident by the Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, CA. […] An asphalt berm (curb) along the downslope edge of the road protects the slopes below from rainfall runoff from the road surface. […] Typically, the sieved material represents at least 80% of the total collected material. For analysis, these sediments are packed into one of the same counting containers as are used for soil samples. These procedures were followed for the samples listed in Table A.5.
The June 9, sample result was 132.4 Bq/kg of cesium 134 + 137 (3,579 pCi/kg).
Winter forage vegetation at the California dairy farm had combined cesium 134 + 137 equaling 0.299 pCi/gram or 299 pCi/kg.
Cesium-134 levels would be even higher than reported due to the 9 months of radioactive decay that took place before testing occurred (37.5% into its 2-year half-life).
No reason is stated for the 9-month gap between when the vegetation sample was harvested and when it was tested.