No, the Assessor raises or lowers the values of property according to the market value of real estate or in the case of agricultural land, according to productivity and CSR.
Assessments are set January 1st of each year, while the tax levies (tax rates) on these assessments are not set until July of the following year. (Example, the assessment notices from April 2011 were for the January 1, 2011 assessment. Tax levies for these values will be set in June of 2012 based on what the different taxing authorities budget in March and April 2012 for the next fiscal year of July 2012 - June 2013.)
The taxing authorities you pay property taxes to are listed at the bottom of your tax statement each year, along with their budget information and a breakdown of how much you are paying to each taxing body.