Does California have sugar or red maples? Or yellow birch?
Sugar maples have the highest sugar concentration. Usually 40-45 gallons of sap per gallon of syrup. Some make syrup from red maples which is more in the 50-60 gallons of sap per gallon of syrup. In Alaska only have yellow birch and I believe it takes around 80 gallons of sap to make a gallon of syrup.
And yes the sap is nearly clear, to a slight brown tint, if it freezes and you can remove the ice.
I agree with Danno's comment from another thread that though the first sap run is prized by many, I like sap from the end of the run, where it gets darker and to me, more flavorful.
Usually tapping in the north begins from mid-Febraruy to mid-March. It flow when the day time temps are above freezing and the night time temps are below freezing. What you are collecting is the sap that is stored in the roots during the winter. Sap can run for as little as a week or as long as a month. Just depends on the weather. The more canopy the tree has the higher the sugar concentration, plus fertility of the soil plays a factor too.