The that invaded nostrils all over the city Thursday appears to have been solved, thanks to some digging (for information) by Napa County workers.
Those who detected a bovine influence to the atmosphere were on the right track, according to an email from county public information officer Elizabeth Emmett that afternoon:
Staff checked in with the Bay Area Air Quality Management District to see what BAAQMD knew about the organic odor that is wafting over Napa County today.
Staff there suggested that the source of the smell is the Cullinan Ranch Marsh Restoration Project.
In a nut shell, the State is restoring the area, which is currently a cattle ranch, to a tidal flux area. Currently they are digging up old soil, which is releasing “marsh gas” (which has a sulphur smell). The gas is heavy and influenced by wind patterns.
The location of the project is at Hwy 37 at the Mare Island Bridge. Additional information can be found at http://restorecullinan.info/intro.aspx.
Some Patch readers took issue with the "sulphur" description, which may have been a BAAQMD euphemism for the four-letter barnyard word that was on many of our minds as the stench pervaded.
A shift in the wind appears to have cleared the air today.