Marin County residents and commuters may see smoke coming from a controlled burn near Novato. A 200-acre controlled burn along Big Rock Ridge began yesterday and will continue through Thursday. Smoke will be visible all three days. This is a fire fuel reduction effort to mitigate future fire risk. The burn is being done by several fire agencies with an assist from PG&E which is loaning them a Black Hawk helicopter, equipped with an 850-gallon internal water tank.